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Tobias Christian Nauen
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% \item Size bias
% \end{itemize}
We conduct a comprehensive suit of experiments to validate the effectiveness of our approach.
We compare training on \name, the ImageNet instantiation of \schemename, to training on ImageNet for 7 different models.
Furthermore, we assess the impact of using \name for pretraining on multiple fine-grained downstream datasets.
Additionally, we use \schemename's control over the image distribution to quantify some model behaviors and biases.
We conduct a comprehensive suit of experiments to validate the effectiveness of our approach,
% We compare training on \name, the ImageNet instantiation of \schemename, to training on ImageNet for 10 different models.
comparing ImageNet-training with and without \schemename for 10 different models.
Furthermore, we assess the impact of using \schemename for pretraining on multiple fine-grained downstream datasets.
Finally, we exploit \schemename's control over the image distribution to quantify model behaviors and biases.
We always report the mean and standard deviation of three independent training runs.
\subsection{Design Choices of \schemename}
\subsection{Design Choices of ForAug}
\label{sec:ablation}
We start by ablating the design choices of \schemename.
For this, we revert to TinyImageNet \cite{Le2015}, a subset of ImageNet containing 200 categories with 500 images each, and Tiny\name, a version of \schemename derived from TinyImageNet.
\Cref{tab:ablation} presents the results of these ablations.
We start by ablating the design choices of \schemename on TinyImageNet~\cite{Le2015}, a subset of ImageNet containing 200 categories with 500 images each. %, and Tiny\name, the application of \schemename to TinyImageNet.
% \Cref{tab:ablation} presents the results of these ablations.
\Cref{tab:ablation-segment} presents ablations for segmentation and \Cref{tab:ablation-recombine} for recombination.
\begin{table*}[t]
\begin{table}
\caption{Ablation of the design decisions in the segmentation phase of \schemename on TinyImageNet.
The first line is our baseline, while the other lines are using \schemename.
We use basic settings with the \emph{same} background strategy during recombination for this experiment.
}
\label{tab:ablation-segment}
\centering
\resizebox{\textwidth}{!}{
\begin{tabular}{lccccccccccccc}
\small
\resizebox{.9\columnwidth}{!}{
\begin{tabular}{cccc}
\toprule
\multirow{2}{*}{Dataset} & Detect. & Infill & FG. & Augmentation & BG. & BG. & edge & original & \multicolumn{2}{c}{TinyImageNet Accuracy} \\
& prompt & Model & size & Order & strategy & pruning & smoothing & image mixing & ViT-Ti [\%] & ViT-S [\%] \\
\cmidrule(r){1-1} \cmidrule(lr){2-9} \cmidrule(l){10-11}
TinyImageNet & & & & & & & & & $66.1\pm0.5$ & $68.3\pm0.7$ \\
Tiny\name & specific & LaMa \cite{Suvorov2021} & mean & crop$\to$paste$\to$color & same & - & - & \gtxt{-} & $64.6\pm0.5$ & $70.0\pm0.6$ \\
\gtxt{Tiny\name} & \gtxt{specific} & \gtxt{LaMa \cite{Suvorov2021}} & range & \gtxt{crop$\to$paste$\to$color} & \gtxt{same} & \gtxt{-} & \gtxt{-} & \gtxt{-} & $65.5\pm0.4$ & $71.2\pm0.5$ \\
\gtxt{Tiny\name} & general & \gtxt{LaMa \cite{Suvorov2021}} & \gtxt{range} & \gtxt{crop$\to$paste$\to$color} & \gtxt{same} & \gtxt{-} & \gtxt{-} & \gtxt{-} & $66.4\pm0.6$ & $72.9\pm0.6$ \\
\gtxt{Tiny\name} & \gtxt{general} & Att. Eraser \cite{Sun2024} & \gtxt{range} & \gtxt{crop$\to$paste$\to$color} & \gtxt{same} & \gtxt{-} & \gtxt{-} & \gtxt{-} & $67.5\pm1.2$ & $72.4\pm0.5$ \\
\gtxt{Tiny\name} & \gtxt{general} & \gtxt{Att. Eraser \cite{Sun2024}} & \gtxt{range} & paste$\to$crop$\to$color & \gtxt{same} & \gtxt{-} & \gtxt{-} & \gtxt{-} & $67.1\pm1.2$ & $72.9\pm0.5$ \\
\gtxt{Tiny\name} & \gtxt{general} & \gtxt{Att. Eraser \cite{Sun2024}} & \gtxt{range} & \gtxt{paste$\to$crop$\to$color} & \gtxt{same} & 1.0 & \gtxt{-} & \gtxt{-} & $67.0\pm1.2$ & $73.0\pm0.3$ \\
\gtxt{Tiny\name} & \gtxt{general} & \gtxt{Att. Eraser \cite{Sun2024}} & \gtxt{range} & \gtxt{paste$\to$crop$\to$color} & \gtxt{same} & 0.8 & \gtxt{-} & \gtxt{-} & $67.2\pm1.2$ & $72.9\pm0.8$ \\
\gtxt{Tiny\name} & \gtxt{general} & \gtxt{Att. Eraser \cite{Sun2024}} & \gtxt{range} & \gtxt{paste$\to$crop$\to$color} & \gtxt{same} & 0.6 & \gtxt{-} & \gtxt{-} & $67.5\pm1.0$ & $72.8\pm0.7$ \\
\gtxt{Tiny\name} & \gtxt{general} & \gtxt{Att. Eraser \cite{Sun2024}} & \gtxt{range} & \gtxt{paste$\to$crop$\to$color} & \gtxt{same} & \gtxt{0.8} & $\sigma_\text{max} = 2.0$ & \gtxt{-} & $67.2\pm0.4$ & $72.9\pm0.5$ \\
\gtxt{Tiny\name} & \gtxt{general} & \gtxt{Att. Eraser \cite{Sun2024}} & \gtxt{range} & \gtxt{paste$\to$crop$\to$color} & \gtxt{same} & \gtxt{0.8} & $\sigma_\text{max} = 4.0$ & \gtxt{-} & $65.9\pm0.5$ & $72.4\pm0.6$ \\
\gtxt{Tiny\name} & \gtxt{general} & \gtxt{Att. Eraser \cite{Sun2024}} & \gtxt{range} & \gtxt{paste$\to$crop$\to$color} & \gtxt{same} & \gtxt{0.8} & \gtxt{-} & $p=0.2$ & $69.8\pm0.5$ & $75.0\pm0.3$ \\
\gtxt{Tiny\name} & \gtxt{general} & \gtxt{Att. Eraser \cite{Sun2024}} & \gtxt{range} & \gtxt{paste$\to$crop$\to$color} & \gtxt{same} & \gtxt{0.8} & \gtxt{-} & $p=0.33$ & $69.5\pm0.4$ & $75.2\pm1.0$ \\
\gtxt{Tiny\name} & \gtxt{general} & \gtxt{Att. Eraser \cite{Sun2024}} & \gtxt{range} & \gtxt{paste$\to$crop$\to$color} & \gtxt{same} & \gtxt{0.8} & \gtxt{-} & $p=0.5$ & $70.3\pm1.0$ & $74.2\pm0.2$ \\
\gtxt{Tiny\name} & \gtxt{general} & \gtxt{Att. Eraser \cite{Sun2024}} & \gtxt{range} & \gtxt{paste$\to$crop$\to$color} & \gtxt{same} & \gtxt{0.8} & \gtxt{-} & linear & $70.1\pm0.7$ & $74.9\pm0.8$ \\
\gtxt{Tiny\name} & \gtxt{general} & \gtxt{Att. Eraser \cite{Sun2024}} & \gtxt{range} & \gtxt{paste$\to$crop$\to$color} & \gtxt{same} & \gtxt{0.8} & \gtxt{-} & reverse lin. & $67.6\pm0.2$ & $73.2\pm0.3$ \\
\gtxt{Tiny\name} & \gtxt{general} & \gtxt{Att. Eraser \cite{Sun2024}} & \gtxt{range} & \gtxt{paste$\to$crop$\to$color} & \gtxt{same} & \gtxt{0.8} & \gtxt{-} & cos & $71.3\pm1.0$ & $75.7\pm0.8$ \\
\gtxt{Tiny\name} & \gtxt{general} & \gtxt{Att. Eraser \cite{Sun2024}} & \gtxt{range} & \gtxt{paste$\to$crop$\to$color} & \gtxt{same} & \gtxt{0.8} & $\sigma_\text{max} = 4.0$ & \gtxt{cos} & $70.0\pm0.8$ & $75.5\pm0.7$ \\
\gtxt{Tiny\name} & \gtxt{general} & \gtxt{Att. Eraser \cite{Sun2024}} & \gtxt{range} & \gtxt{paste$\to$crop$\to$color} & orig. & \gtxt{0.8} & \gtxt{$\sigma_\text{max} = 4.0$} & \gtxt{cos} & $67.2\pm0.9$ & $69.9\pm1.0$ \\
\gtxt{Tiny\name} & \gtxt{general} & \gtxt{Att. Eraser \cite{Sun2024}} & \gtxt{range} & \gtxt{paste$\to$crop$\to$color} & all & \gtxt{0.8} & \gtxt{$\sigma_\text{max} = 4.0$} & \gtxt{cos} & $70.1\pm0.7$ & $77.5\pm0.6$ \\
\multirow{2.5}{*}{\makecell{Detect. \\Prompt}} & \multirow{2.5}{*}{\makecell{Infill \\ Model}} & \multicolumn{2}{c}{TinyImageNet Accuracy [\%]} \\
\cmidrule{3-4}
& & ViT-Ti & ViT-S \\
\midrule
\name & \gtxt{general} & \gtxt{Att. Eraser \cite{Sun2024}} & \gtxt{range} & \gtxt{paste$\to$crop$\to$color} & \gtxt{same} & \gtxt{0.8} & \gtxt{-} & \gtxt{cos} & - & $80.5\pm0.1$ \\
\gtxt{\name} & \gtxt{general} & \gtxt{Att. Eraser \cite{Sun2024}} & \gtxt{range} & \gtxt{paste$\to$crop$\to$color} & \gtxt{same} & \gtxt{0.8} & $\sigma_\text{max} = 4.0$ & \gtxt{cos} & - & $80.7\pm0.1$ \\
\gtxt{\name} & \gtxt{general} & \gtxt{Att. Eraser \cite{Sun2024}} & \gtxt{range} & \gtxt{paste$\to$crop$\to$color} & all & \gtxt{0.8} & \gtxt{$\sigma_\text{max} = 4.0$} & \gtxt{cos} & - & $81.3\pm0.1$ \\
\multicolumn{2}{l}{\textbf{TinyImageNet}} & $66.1 \pm 0.5$ & $68.3 \pm 0.7$ \\
specific & LaMa \cite{Suvorov2021} & $65.5 \pm 0.4$ & $71.2 \pm 0.5$ \\
general & \gtxt{LaMa \cite{Suvorov2021}} & $66.4 \pm 0.6$ & $72.9 \pm 0.6$ \\
\gtxt{general} & Att. Eraser \cite{Sun2024} & $67.5 \pm 1.2$ & $72.4 \pm 0.5$ \\
\bottomrule
\end{tabular}}
\caption{Ablation of design decisions of Tiny\name on TinyImageNet and \name on ImageNet.}
\label{tab:ablation}
\end{table*}
\end{table}
\begin{table}[t]
\caption{Ablation of the recombination phase of \schemename on TinyImageNet (top) and ImageNet (bottom). The first experiments use the initial segmentation settings with LaMa \cite{Suvorov2021}.}
\label{tab:ablation-recombine}
\centering
\resizebox{\columnwidth}{!}{
\begin{tabular}{ccccccccccc}
\toprule
% FG. & Augment. & BG. & BG. & Edge & Original & \multicolumn{2}{c}{Accuracy [\%]} \\
% Size & Order & Strat. & Prune & Smoothing & Mixing & ViT-Ti & ViT-S \\
\multirow{2.5}{*}{\makecell{FG. \\size}} & \multirow{2.5}{*}{\makecell{Augment.\\Order}} & \multirow{2.5}{*}{\makecell{BG\\Strat.}} & \multirow{2.5}{*}{\makecell{BG.\\Prune}} & \multirow{2.5}{*}{\makecell{Original\\Mixing}} & \multirow{2.5}{*}{\makecell{Edge\\Smooth.}} & \multicolumn{2}{c}{Accuracy [\%]} \\
\cmidrule{7-8}
& & & & & & ViT-Ti & ViT-S \\
\midrule
% TinyImageNet & & & & & & & $66.1\pm0.5$ & $68.3\pm0.7$ \\
\multicolumn{6}{l}{\textbf{TinyImageNet}} & \gtxt{$66.1\pm0.5$} & \gtxt{$68.3\pm0.7$} \\
mean & crop$\to$paste & same & - & - & \gtxt{-} & $64.6\pm0.5$ & $70.0\pm0.6$ \\
range & \gtxt{crop$\to$paste} & \gtxt{same} & \gtxt{-} & \gtxt{-} & \gtxt{-} & $65.5\pm0.4$ & $71.2\pm0.5$ \\
\midrule
% \gtxt{range} & \gtxt{crop$\to$paste} & \gtxt{same} & \gtxt{-} & \gtxt{-} & \gtxt{-} & $66.4\pm0.6$ & $72.9\pm0.6$ \\
{range} & {crop$\to$paste} & {same} & {-} & {-} & {-} & $67.5\pm1.2$ & $72.4\pm0.5$ \\
\gtxt{range} & paste$\to$crop & \gtxt{same} & \gtxt{-} & \gtxt{-} & \gtxt{-} & $67.1\pm1.2$ & $72.9\pm0.5$ \\
\gtxt{range} & \gtxt{paste$\to$crop} & \gtxt{same} & 1.0 & \gtxt{-} & \gtxt{-} & $67.0\pm1.2$ & $73.0\pm0.3$ \\
\gtxt{range} & \gtxt{paste$\to$crop} & \gtxt{same} & 0.8 & \gtxt{-} & \gtxt{-} & $67.2\pm1.2$ & $72.9\pm0.8$ \\
\gtxt{range} & \gtxt{paste$\to$crop} & \gtxt{same} & 0.6 & \gtxt{-} & \gtxt{-} & $67.5\pm1.0$ & $72.8\pm0.7$ \\
% \gtxt{range} & \gtxt{paste$\to$crop} & \gtxt{same} & \gtxt{0.8} & $\sigma_\text{max} = 2.0$ & \gtxt{-} & $67.2\pm0.4$ & $72.9\pm0.5$ \\
% \gtxt{range} & \gtxt{paste$\to$crop} & \gtxt{same} & \gtxt{0.8} & $\sigma_\text{max} = 4.0$ & \gtxt{-} & $65.9\pm0.5$ & $72.4\pm0.6$ \\
\gtxt{range} & \gtxt{paste$\to$crop} & \gtxt{same} & \gtxt{0.8} & $p=0.2$ & \gtxt{-} & $69.8\pm0.5$ & $75.0\pm0.3$ \\
\gtxt{range} & \gtxt{paste$\to$crop} & \gtxt{same} & \gtxt{0.8} & $p=0.33$ & \gtxt{-} & $69.5\pm0.4$ & $75.2\pm1.0$ \\
\gtxt{range} & \gtxt{paste$\to$crop} & \gtxt{same} & \gtxt{0.8} & $p=0.5$ & \gtxt{-} & $70.3\pm1.0$ & $74.2\pm0.2$ \\
\gtxt{range} & \gtxt{paste$\to$crop} & \gtxt{same} & \gtxt{0.8} & linear & \gtxt{-} & $70.1\pm0.7$ & $74.9\pm0.8$ \\
\gtxt{range} & \gtxt{paste$\to$crop} & \gtxt{same} & \gtxt{0.8} & reverse lin. & \gtxt{-} & $67.6\pm0.2$ & $73.2\pm0.3$ \\
\gtxt{range} & \gtxt{paste$\to$crop} & \gtxt{same} & \gtxt{0.8} & cos & \gtxt{-} & $71.3\pm1.0$ & $75.7\pm0.8$ \\
\gtxt{range} & \gtxt{paste$\to$crop} & \gtxt{same} & \gtxt{0.8} & \gtxt{cos} & $\sigma_\text{max} = 4.0$ & $70.0\pm0.8$ & $75.5\pm0.7$ \\
\gtxt{range} & \gtxt{paste$\to$crop} & orig. & \gtxt{0.8} & \gtxt{cos} & \gtxt{$\sigma_\text{max} = 4.0$} & $67.2\pm0.9$ & $69.9\pm1.0$ \\
\gtxt{range} & \gtxt{paste$\to$crop} & all & \gtxt{0.8} & \gtxt{cos} & \gtxt{$\sigma_\text{max} = 4.0$} & $70.1\pm0.7$ & $77.5\pm0.6$ \\
\midrule
\multicolumn{6}{l}{\textbf{ImageNet}} & \gtxt{-} & \gtxt{$79.1\pm0.1$} \\
\gtxt{range} & \gtxt{paste$\to$crop} & \gtxt{same} & \gtxt{0.8} & \gtxt{cos} & \gtxt{-} & - & $80.5\pm0.1$ \\
\gtxt{range} & \gtxt{paste$\to$crop} & \gtxt{same} & \gtxt{0.8} & \gtxt{cos} & $\sigma_\text{max} = 4.0$ & - & $80.7\pm0.1$ \\
\gtxt{range} & \gtxt{paste$\to$crop} & all & \gtxt{0.8} & \gtxt{cos} & \gtxt{$\sigma_\text{max} = 4.0$} & - & $81.4\pm0.1$ \\
\bottomrule
\end{tabular}}
\end{table}
\textbf{Prompt.}
% We present the ablation of our main design decisions in \Cref{tab:ablation}.
First, we evaluate the type of prompt used to detect the foreground object.
Here, the \emph{general} prompt, which contains the class and the more general object category, outperforms only having the class name (\emph{specific}).
\textbf{Inpainting.} Attentive Eraser \cite{Sun2024} produces superior results compared to LaMa \cite{Suvorov2021} (see \Cref{sec:infill-model-comparison} for examples).
\textbf{Inpainting.} Among inpainting models, Attentive Eraser~\cite{Sun2024} produces slightly better results compared to LaMa~\cite{Suvorov2021} ($+0.5$ p.p. on average).
For inpainting examples, see the supplementary material.
% (see the supplementary material for examples).
% When comparing the infill models, the GAN-based LaMa \cite{Suvorov2021} gets outperformed by the Attentive Eraser \cite{Sun2024}.
\textbf{Foreground size}
@@ -86,22 +120,26 @@ This suggests that the added variability is beneficial.
\textbf{Order of data augmentation.}
% (1) Applying the image crop related augmentations \emph{before} pasting the foreground object and the color-based ones \emph{after} pasting or (2) applying all data augmentations after pasting the foreground object.
% While results are ambiguous, we choose the second strategy, as it improves the performance of ViT-S, although not the one of ViT-Ti.
Applying all augmentations after foreground-background recombination (\emph{paste$\to$crop$\to$color}) slightly improves ViT-S's performance compared to applying crop-related augmentations before pasting (\emph{crop$\to$paste$\to$color}).
For ViT-Ti, the results are ambiguous.
Applying all augmentations after foreground-background recombination (\emph{paste$\to$crop$\to$color}) improves ViT-S's performance compared to applying crop-related augmentations before pasting (\emph{crop$\to$paste$\to$color}).
ViT-Ti results are ambiguous.
\textbf{Background pruning.}
When it comes to the choice of backgrounds to use, we test two pruning thresholds ($t_\text{prune}$) to exclude backgrounds with excessive inpainting.
When it comes to the backgrounds to use, we test different pruning thresholds ($t_\text{prune}$) to exclude backgrounds with large inpainting.
% and only use backgrounds with an relative size of the infilled region of at most $t_\text{prune}$ (exclusive).
A threshold of $t_\text{prune}=1.0$ means that we use all backgrounds that are not fully infilled.
% We find that the background pruning does not significantly impact the models' performance.
% We choose $t_\text{prune}=0.8$ for the following experiments to exclude backgrounds that are mostly artificial.
Varying $t_\text{prune}$ has minimal impact.
Therefore, we choose $t_\text{prune} = 0.8$ to exclude predominantly artificial backgrounds.
Similarly, applying edge smoothing to foreground masks with Gaussian blurring actually hurts performance on Tiny\name, but slightly improves it on \name.
We choose $t_\text{prune} = 0.8$ to exclude predominantly artificial backgrounds.
% One of the most important design decisions is the mixing of the original dataset with \name.
\textbf{Mixing} \name with the original ImageNet data proves crucial.
While constant and linear mixing schedules improve performance over no mixing by $2-3$ p.p. compared to only using Tiny\name, the cosine annealing schedule yields the best results, boosting accuracy by another $0.5-1$ p.p.
\textbf{Mixing} \schemename-augmented samples with the original ImageNet data proves crucial.
While constant and linear mixing schedules improve performance over no mixing by $2-3$ p.p. compared to only augmented samples, the cosine annealing schedule proves optimal, boosting accuracy by $3-4$ p.p.
\textbf{Edge smoothing.}
We evaluate the impact of using Gaussian blurring to smooth the edges of the foreground masks.
% Similarly, applying edge smoothing to foreground masks with Gaussian blurring actually hurts performance on Tiny\name, but slightly improves it on \name.
For larger models, this gives us a slight performance boost on the full ImageNet (second to last line in \Cref{tab:ablation-recombine}).
\textbf{Background strategy.}
Another point is the allowed choice of background image for each foreground object.
@@ -116,302 +154,344 @@ Another point is the allowed choice of background image for each foreground obje
We compare using the original background, a background from the same class, and any background.
These strategies go from low diversity and high shared information content between the foreground and background to high diversity and low shared information content.
For \emph{ViT-Ti}, the latter two strategies perform comparably, while \emph{ViT-S} benefits from the added diversity of using any background.
The same is true when training on the full (ImageNet) version of \name.
The same is true when training on the full ImageNet.
\begin{figure}
\centering
\includegraphics[width=.7\columnwidth]{img/bates.pdf}
\caption{Plot of the probability distribution function (PDF) of the extended Bates distribution for different parameters $\eta$. Higher values of $\eta$ concentrate the distribution around the center.}
\label{fig:bates-pdf}
\end{figure}
\begin{table}
\caption{Accuracy of ViT-S on TinyImageNet (TIN) in percent using \schemename with different foreground position distributions by varying the Bates parameter $\eta$.
The best performance is achieved when using the uniform distribution ($\eta=1$) for training.}
\label{tbl:foreground-eta}
\centering
\resizebox{\columnwidth}{!}{
\small
\resizebox{.9\columnwidth}{!}{
\begin{tabular}{ccccccc}
\toprule
\multirow{2.5}{*}{\makecell{Training Set/ \\ Bates Parameter}} & \multirow{2.5}{*}{TIN} & \multicolumn{5}{c}{Tiny\name} \\
\multirow{2.5}{*}{\makecell{Bates Parameter \\during training}} & \multirow{2.5}{*}{\makecell{TIN \\w/o \schemename}} & \multicolumn{5}{c}{TIN w/ \schemename} \\
\cmidrule(l){3-7}
& & $\eta=-3$ & $-2$ & $1/-1$ & $2$ & $3$ \\
& & $\eta=-3$ & $-2$ & $1/-1$ & $2$ & $3$ \\
\midrule
TinyImageNet & 68.9 & 60.5 & 60.2 & 60.8 & 62.6 & 63.1 \\
$\eta=-3$ & 71.3 & 79.3 & 79.5 & 79.1 & 79.3 & 79.1 \\
$\eta=-2$ & 71.5 & 80.0 & 78.7 & 79.3 & 79.1 & 78.8 \\
$\eta=1/-1$ & 72.3 & 79.5 & 78.9 & 80.2 & 79.7 & 80.4 \\
$\eta=2$ & 71.3 & 78.2 & 77.8 & 79.1 & 79.6 & 79.9 \\
$\eta=3$ & 71.4 & 77.2 & 76.9 & 78.6 & 79.6 & 79.7 \\
Baseline & 68.9 & 60.5 & 60.2 & 60.8 & 62.6 & 63.1 \\
$\eta=-3$ & 71.3 & 79.3 & 79.5 & 79.1 & 79.3 & 79.1 \\
$\eta=-2$ & 71.5 & 80.0 & 78.7 & 79.3 & 79.1 & 78.8 \\
$\eta=1/-1$ & 72.3 & 79.5 & 78.9 & 80.2 & 79.7 & 80.4 \\
$\eta=2$ & 71.3 & 78.2 & 77.8 & 79.1 & 79.6 & 79.9 \\
$\eta=3$ & 71.4 & 77.2 & 76.9 & 78.6 & 79.6 & 79.7 \\
\bottomrule
\end{tabular}}
\caption{Accuracy of ViT-S trained on TinyImageNet (TIN) and Tiny\name with different foreground position distributions by varying the parameter of a Bates distribution $\eta$.
The best performance is achieved using the uniform distribution ($\eta=1$).}
\end{table}
\textbf{Foreground position.}
Finally, we analyze the foreground object's positioning in the image.
We utilize an extended Bates distribution to sample the position of the foreground object.
The Bates distribution~\cite{Bates1955} with parameter $\eta \geq 1$ is the mean of $\eta$ independent uniformly distributed random variables \cite{Jonhson1995}.
Therefore, the larger $\eta$, the more concentrated the distribution is around the center.
We extend this concept to $\eta \leq -1$ by defining ${X \sim \text{Bates}(\eta) :\Leftrightarrow s(X) \sim \text{Bates}(-\eta)}$ for $\eta \leq 1$ with $s$ being the sawtooth function on $[0, 1]$:
\begin{align}
s(x) = \begin{cases}
x + 0.5 & \text{if } 0 < x < 0.5 \\
x - 0.5 & \text{if } 0.5 \leq x \leq 1
\end{cases}
\end{align}
Note that $s \circ s = \id$ on $[0, 1]$.
This way, distributions with $\eta \leq -1$ are more concentrated around the borders.
$\eta = 1$ and $\eta = -1$ both correspond to the uniform distribution.
The PDF of this extended Bates distribution is visualized in \Cref{fig:bates-pdf}.
When sampling more towards the center of the image, the difficulty of the task is reduced, which then reduces the performance on TinyImageNet.
This is reflected in the performance when evaluating on Tiny\name with $\eta=2$ and $\eta=3$ compared to $\eta=-1/1$.
Finally, we analyze the foreground object's positioning in the image, using a
generalization of the Bates distribution~\cite{Bates1955} with parameter $\eta \in \Z$.
The Bates distribution presents an easy way to sample from a bounded domain with just one hyperparameter that controls its concentration.
$\eta = 1/-1$ corresponds to the uniform distribution; $\eta > 1$ concentrates the distribution around the center; and for $\eta < -1$, the distribution is concentrated at the borders (see supplementary material for details).
% We utilize an extended Bates distribution to sample the position of the foreground object.
% The Bates distribution with parameter $\eta \geq 1$ is the mean of $\eta$ independent uniformly distributed random variables \cite{Jonhson1995}.
% The larger $\eta$, the more concentrated the distribution is at the center, $\eta < -1$ concentrates the distribution at the edges.
% We extend this concept to $\eta \leq -1$, shifting the distribution away from the center and towards the edges.
When sampling more towards the center of the image, the difficulty of the task is reduced, which reduces performance on TinyImageNet (\Cref{tbl:foreground-eta}).
This is reflected in the performance when evaluating using \schemename with $\eta=2$ and $\eta=3$ compared to $\eta=-1/1$.
We observe a similar reduction for $\eta < -1$.
This experiment is conducted using the LaMa infill model.
% This experiment is conducted using the LaMa infill model.
\begin{table}
\centering
\small
\begin{tabular}{lccc}
\toprule
Dataset & Classes & \makecell{Training \\ Images} & \makecell{Validation \\ Images} \\
\midrule
TinyImageNet & 200 & 100,000 & 10,000 \\
Tiny\name & 200 & 99,404 & 9,915 \\
ImageNet & 1,000 & 1,281,167 & 50,000 \\
\name & 1,000 & 1,274,557 & 49,751 \\
\bottomrule
\end{tabular}
\caption{Dataset statistics for TinyImageNet, Tiny\name, ImageNet, and \name. For \name and Tiny\name we report the number of foreground/background pairs.}
\caption{Dataset statistics for TinyImageNet and ImageNet with and without \schemename. For \schemename we report the number of foreground/background pairs.}
\label{tab:dataset-stats}
\centering
\resizebox{.9\columnwidth}{!}{
\begin{tabular}{l S[table-format=4.0] S[table-format=7.0] S[table-format=5.0]}
\toprule
Dataset & {Classes} & {\makecell{Training \\ Images}} & {\makecell{Validation \\ Images}} \\
\midrule
TinyImageNet & 200 & 100000 & 10000 \\
TinyImageNet + \schemename & 200 & 99404 & 9915 \\
ImageNet & 1000 & 1281167 & 50000 \\
ImageNet + \schemename & 1000 & 1274557 & 49751 \\
\bottomrule
\end{tabular}}
\end{table}
After fixing the optimal design parameters in \Cref{tab:ablation} (last row), we construct the full \name dataset using the entire ImageNet dataset.
\Cref{tab:dataset-stats} compares the dataset statistics of ImageNet and \name.
After fixing the optimal design parameters in \Cref{tab:ablation-segment,tab:ablation-recombine} (last rows), we run \schemename's segmentation step on the entire ImageNet dataset.
\Cref{tab:dataset-stats} shows the resulting dataset statistics.
% The slightly lower number of images in \name is due to \emph{Grounded SAM} returning no or invalid detections for some images.
The slightly reduced image count in \name is due to instances where Grounded SAM failed to produce valid object detections.
The slightly reduced image count for \schemename is due to instances where Grounded SAM fails to produce valid segmentation masks.
\subsection{Image Classification Results}
\begin{table}
\centering
\begin{tabular}{lccc}
\toprule
\multirow{2.5}{*}{Model} & \multicolumn{2}{c}{\makecell{ImageNet Accuracy \\ when trained on}} & \multirow{2.5}{*}{Delta} \\
\cmidrule(lr){2-3}
& ImageNet & \name & \\
\midrule
ViT-S & $79.1\pm0.1$ & $81.4\pm0.1$ & \grntxt{+2.3} \\
ViT-B & $77.6\pm0.2$ & $81.1\pm0.4$ & \grntxt{+3.5} \\
ViT-L & $75.3\pm0.4$ & $79.8\pm0.1$ & \grntxt{+4.5} \\
\midrule
Swin-Ti & $77.9\pm0.2$ & $79.7\pm0.1$ & \grntxt{+1.8} \\
Swin-S & $79.4\pm0.1$ & $80.6\pm0.1$ & \grntxt{+1.2} \\
\midrule
ResNet-50 & $78.3\pm0.1$ & $78.8\pm0.1$ & \grntxt{+0.5} \\
ResNet-101 & $79.4\pm0.1$ & $80.4\pm0.1$ & \grntxt{+1.0} \\
\bottomrule
\end{tabular}
\caption{ImageNet results of models trained on \name and on ImageNet directly. \name improves the performance of all models in our test.}
\caption{ImageNet results of models trained on ImageNet with and without \schemename. \schemename improves the performance of most models, with a larger gain for larger models.}
\label{tab:imagenet-results}
\end{table}
\Cref{tab:imagenet-results} compares the ImageNet performance of models trained on \name and ones trained directly on ImageNet.
We adopt the training setup of \cite{Nauen2023} and \cite{Touvron2022} (details in \Cref{sec:training_setup}) for training ViT \cite{Dosovitskiy2021}, Swin \cite{Liu2021} and ResNet \cite{He2016} models.
Notably, \name improves performance across all tested architectures, including the ResNet models (up to $1$ p.p.), demonstrating benefits beyond Transformers.
For Transformer models, we observe improvements from $1.2$ p.p. to $4.5$ p.p.
This improvement is more substantial for the larger models, with ViT-L gaining $4.5$ p.p. in accuracy.
\name's improvements mostly counteract the drop in performance due to overfitting for large models.
When training on ImageNet, this drop is $3.8$ p.p. from ViT-S to ViT-L, while for \name it is reduced to $1.6$ p.p.
\begin{table}
\centering
\resizebox{\columnwidth}{!}{\begin{tabular}{lccccc}
\small
\resizebox{.8\columnwidth}{!}{\begin{tabular}{lccc}
\toprule
Model & Aircraft & Cars & Flowers & Food & Pets \\
\multirow{2.5}{*}{Model} & \multicolumn{2}{c}{\makecell{ImageNet Accuracy [\%]}} & \multirow{2.5}{*}{Delta} \\
\cmidrule(lr){2-3}
& w/o \schemename & w/ \schemename & \\
\midrule
ViT-S @ ImageNet & $72.4\pm1.0$ & $89.8\pm0.3$ & $94.5\pm0.2$ & $89.1\pm0.1$ & $93.8\pm0.2$ \\
ViT-S @ \name & $78.6\pm0.5$ & $92.2\pm0.2$ & $95.5\pm0.2$ & $89.6\pm0.1$ & $94.5\pm0.2$ \\
& \grntxt{+6.2} & \grntxt{+2.4} & \grntxt{+1.0} & \grntxt{+0.5} & \grntxt{+0.7} \\
\cmidrule(r){1-1}
ViT-B @ ImageNet & $71.7\pm0.5$ & $90.0\pm0.2$ & $94.8\pm0.4$ & $89.8\pm0.2$ & $94.1\pm0.4$ \\
ViT-B @ \name & $79.0\pm2.2$ & $93.3\pm0.1$ & $ 96.5\pm0.1$ & $90.9\pm0.1$ & $95.1\pm0.4$ \\
& \grntxt{+7.3} & \grntxt{+3.3} & \grntxt{+1.7} & \grntxt{+1.1} & \grntxt{+1.0} \\
\cmidrule(r){1-1}
ViT-L @ ImageNet & $72.1\pm1.0$ & $88.8\pm0.3$ & $94.4\pm0.3$ & $90.1\pm0.2$ & $94.2\pm0.4$ \\
ViT-L @ \name & $77.6\pm1.2$ & $89.1\pm0.2$ & $96.6\pm0.1$ & $91.3\pm0.1$ & $95.1\pm0.1$ \\
& \grntxt{+5.5} & \grntxt{+0.3} & \grntxt{+2.2} & \grntxt{+1.2} & \grntxt{+0.9} \\
ViT-S & $79.1\pm0.1$ & $81.4\pm0.1$ & \grntxt{$+2.3$} \\
ViT-B & $77.6\pm0.2$ & $81.1\pm0.4$ & \grntxt{$+3.5$} \\
ViT-L & $75.3\pm0.4$ & $79.8\pm0.1$ & \grntxt{$+4.5$} \\
\midrule
Swin-Ti @ ImageNet & $77.0\pm0.1$ & $91.3\pm0.6$ & $95.9\pm0.1$ & $90.0\pm0.2$ & $94.2\pm0.1$ \\
Swin-Ti @ \name & $81.1\pm0.8$ & $92.8\pm0.4$ & $96.2\pm0.1$ & $90.4\pm0.3$ & $94.8\pm0.5$ \\
& \grntxt{+4.1} & \grntxt{+2.5} & \grntxt{+0.3} & \grntxt{+0.4} & \grntxt{+0.6} \\
\cmidrule(r){1-1}
Swin-S @ ImageNet & $75.7\pm1.4$ & $91.0\pm0.3$ & $95.9\pm0.5$ & $91.1\pm0.2$ & $94.4\pm0.1$ \\
Swin-S @ \name & $81.4\pm0.2$ & $93.1\pm0.2$ & $96.3\pm0.3$ & $91.2\pm0.2$ & $94.9\pm0.3$ \\
& \grntxt{+5.7} & \grntxt{+2.1} & \grntxt{+1.4} & \grntxt{+0.1} & \grntxt{+0.5} \\
DeiT-S & $80.1 \pm 0.1$ & $80.0\pm0.3$ & \gtxt{$-0.1$} \\
DeiT-B & $81.9 \pm 0.3$ & $81.9\pm0.2$ & \gtxt{$\pm0.0$} \\
DeiT-L & $79.3\pm2.3$ & $82.4\pm0.1$ & \grntxt{$+3.1$} \\
\midrule
ResNet-50 @ ImageNet & $78.2\pm0.5$ & $89.8\pm0.2$ & $91.7\pm0.4$ & $84.4\pm0.2$ & $93.7\pm0.3$ \\
ResNet-50 @ \name & $80.3\pm0.4$ & $90.4\pm0.2$ & $91.7\pm0.2$ & $84.5\pm0.2$ & $93.7\pm0.3$ \\
& \grntxt{+2.1} & \grntxt{+0.6} & \gtxt{$\pm$0} & \grntxt{+0.1} & \gtxt{$\pm$0} \\
\cmidrule(r){1-1}
ResNet-101 @ ImageNet & $78.4\pm0.6$ & $90.3\pm0.1$ & $91.2\pm0.5$ & $86.0\pm0.2$ & $94.3\pm0.2$ \\
ResNet-101 @ \name & $81.4\pm0.5$ & $91.3\pm0.1$ & $92.9\pm0.2$ & $86.3\pm0.1$ & $94.0\pm0.3$ \\
& \grntxt{+3.0} & \grntxt{+1.3} & \grntxt{+1.7} & \grntxt{+0.3} & \textcolor{red}{-0.3} \\
Swin-Ti & $77.9\pm0.2$ & $79.7\pm0.1$ & \grntxt{$+1.8$} \\
Swin-S & $79.4\pm0.1$ & $80.6\pm0.1$ & \grntxt{$+1.2$} \\
\midrule
ResNet-50 & $78.3\pm0.1$ & $78.8\pm0.1$ & \grntxt{$+0.5$} \\
ResNet-101 & $79.4\pm0.1$ & $80.4\pm0.1$ & \grntxt{$+1.0$} \\
\bottomrule
\end{tabular}}
\caption{Downstream accuracy in percent when finetuning on other datasets. Models were pretrained on \name and ImageNet. Pretraining on \name increases Transformer downstream accuracy on all datasets.}
\end{table}
To assess the transferability of \name-trained models, we finetune models pretrained on ImageNet and \name on five fine-grained datasets:
FGVC-Aircraft \cite{Maji2013}, Stanford Cars~\cite{Dehghan2017}, Oxford Flowers \cite{Nilsback2008}, Food-101 \cite{Kaur2017}, and Oxford-IIIT Pets \cite{Parkhi2012}.
While for ResNets, the performance of both training datasets is about the same, for every Transformer, we see the accuracy improve on all downstream dataset by up to 7.3 p.p. and a reduction of error rate of up to $39.3\%$.
In summary, these results demonstrate that the improved representation learning achieved by training on \name translates to superior performance not only on ImageNet, but also on a variety of fine-grained image classification tasks.
\Cref{tab:imagenet-results} compares the ImageNet performance of models trained with and without \schemename.
We adopt the training setup of \cite{Nauen2025} and \cite{Touvron2022} for training ViT \cite{Dosovitskiy2021}, Swin \cite{Liu2021} and ResNet \cite{He2016} (representing CNNs) models as well as the setup of DeiT \cite{Touvron2021b} for that model.
Both setups are using strong data augmentations like RandAugment, CutMix, and Mixup optimized for Transformers (details in supplementary material).
Notably, \schemename improves performance across all tested architectures, including the ResNet models, % (up to $1$ p.p.),
demonstrating benefits beyond Transformers.
For DeiT we only observe benefits on ImageNet for the larger models.
For other transformers, we observe improvements from $1.2$ p.p. to $4.5$ p.p. with increasing gains for larger models.
% This improvement is more substantial for the larger models, with ViT-L gaining $4.5$ p.p. in accuracy.
\schemename's improvements counteract the drop in performance for increasing model sizes.
Without \schemename this drop is $3.8$ p.p. (ViT-S to L), while with \schemename it is reduced to $1.6$ p.p.
For DeiT there is a drop of $0.8$ p.p. from small to large while when using \schemename there is a \emph{gain} of $2.4$ p.p.
\subsection{Further Model Evaluation}
% Additional to just using \name for training, its special properties and posibilities for adjustment of the data distribution make it a valuable tool for evaluating other model properties and biases.
Beyond its use for training, \name's unique properties and controlled data generation capabilities make it a powerful tool for analyzing model behavior and biases.
\paragraph*{Background Robustness}
\begin{table}
\caption{Comparison of \schemename and simple Copy-Paste methods. We train ViT-S on ImageNet using the same 3-augment data augmentation on top of the copy-paste augmentation.}
\label{tab:copy-paste-comparison}
\centering
\begin{tabular}{lccc}
\toprule
\multirow{2.5}{*}{Model} & \multicolumn{2}{c}{\makecell{Background Robustness \\ when trained on}} & \multirow{2.5}{*}{Delta} \\
\cmidrule(lr){2-3}
& ImageNet & \name & \\
\midrule
ViT-S & $0.73\pm0.01$ & $0.99\pm0.01$ & \grntxt{+0.26} \\
ViT-B & $0.72\pm0.01$ & $1.00\pm0.01$ & \grntxt{+0.28} \\
ViT-L & $0.70\pm0.01$ & $1.00\pm0.01$ & \grntxt{+0.30} \\
\midrule
Swin-Ti & $0.72\pm0.01$ & $1.00\pm0.01$ & \grntxt{+0.28} \\
Swin-S & $0.72\pm0.01$ & $1.00\pm0.01$ & \grntxt{+0.28} \\
\midrule
ResNet-50 & $0.79\pm0.01$ & $0.99\pm0.01$ & \grntxt{+0.20} \\
ResNet-101 & $0.79\pm0.01$ & $1.00\pm0.01$ & \grntxt{+0.21} \\
\bottomrule
\end{tabular}
\caption{Evaluation of the background robustness of models trained on \name and on ImageNet directly. Training on \name improves the background robustness of all model to $\approx1.00$, meaning the model is indifferent to the choice of background.}
\label{tab:background-robustness}
\resizebox{\columnwidth}{!}{
\begin{tabular}{lcc S[table-format=+2.1,retain-explicit-plus,detect-inline-weight=math,detect-weight=true]}
\toprule
Augmentation & labels & \makecell{ Accuracy [\%]} & {\makecell{Delta \\to Prev.}} \\
\midrule
% Baseline & & $79.1 \pm 0.1$ \\
Baseline + \textbf{Simple Copy-Paste} & bg & $31.3 \pm 0.6$ & \\
+ mixed labels & fg + bg & $32.0 \pm 0.8$ & +0.7 \\
+ fg labels & fg & $31.6 \pm 0.9$ & -0.4 \\
+ \emph{range} foreground size variation & \gtxt{fg} & $43.0 \pm 1.2$ & \bfseries +11.4 \\
+ infilled backgrounds & \gtxt{fg} & $68.7 \pm 0.2$ & \bfseries +25.7 \\
+ \emph{cos} mixing strategy & \gtxt{fg} & $81.2 \pm 0.1$ & \bfseries +12.5 \\
+ edge smoothing & \gtxt{fg} & $81.3 \pm 0.1$ & +0.1 \\
+ background pruning$=$ \textbf{\schemename} & \gtxt{fg} & $81.4 \pm 0.1$ & +0.1 \\
\bottomrule
\end{tabular}}
\end{table}
\textbf{Comparison to Simple Copy-Paste.}
We compare \schemename to a simple adaption of the Copy-Paste augmentation inspired by \cite{Ge2023,Ghiasi2020,Shermaine2025} in \Cref{tab:copy-paste-comparison}.
Contrary to semantic segmentation we do not have foreground masks available.
Thus, we paste the extracted foreground objects from \emph{\schemename's segmentation stage} onto normal ImageNet images.
% Since such images do not have straight forward classification labels, we test multiple possibilities.
We observe 3 large jumps in accuracy: (\textbf{1}) From our \emph{range} foreground size variation (+11.4\%), (\textbf{2}) from using our infilled backgrounds instead of images from the dataset (+25.7\%), and (\textbf{3}) from our \emph{cos} mixing strategy with non-augmented images (+12.5\%).
\schemename's changes to the naive copy-paste augmentation are thus imperative for good classification performance.
\begin{table}[t]
\caption{Downstream accuracy in percent when finetuning on other datasets. Models are pretrained on ImageNet with and without \schemename. Pretraining using \schemename increases transformer downstream accuracy.
% on all datasets.
}
\label{tab:downstream-results}
\centering
\resizebox{\columnwidth}{!}{\begin{tabular}{lcccccc}
\toprule
Model & \schemename & Aircraft & Cars & Flowers & Food & Pets \\
\midrule
ViT-S & \xmark & $72.4\pm1.0$ & $89.8\pm0.3$ & $94.5\pm0.2$ & $89.1\pm0.1$ & $93.8\pm0.2$ \\
ViT-S & \cmark & $78.6\pm0.5$ & $92.2\pm0.2$ & $95.5\pm0.2$ & $89.6\pm0.1$ & $94.5\pm0.2$ \\
& & \grntxt{$+6.2$} & \grntxt{$+2.4$} & \grntxt{$+1.0$} & \grntxt{$+0.5$} & \grntxt{$+0.7$} \\
\cmidrule(r){1-1}
ViT-B & \xmark & $71.7\pm0.5$ & $90.0\pm0.2$ & $94.8\pm0.4$ & $89.8\pm0.2$ & $94.1\pm0.4$ \\
ViT-B & \cmark & $79.0\pm2.2$ & $93.3\pm0.1$ & $ 96.5\pm0.1$ & $90.9\pm0.1$ & $95.1\pm0.4$ \\
& & \grntxt{$+7.3$} & \grntxt{$+3.3$} & \grntxt{$+1.7$} & \grntxt{$+1.1$} & \grntxt{$+1.0$} \\
\cmidrule(r){1-1}
ViT-L & \xmark & $72.1\pm1.0$ & $88.8\pm0.3$ & $94.4\pm0.3$ & $90.1\pm0.2$ & $94.2\pm0.4$ \\
ViT-L & \cmark & $77.6\pm1.2$ & $89.1\pm0.2$ & $96.6\pm0.1$ & $91.3\pm0.1$ & $95.1\pm0.1$ \\
& & \grntxt{$+5.5$} & \grntxt{$+0.3$} & \grntxt{$+2.2$} & \grntxt{$+1.2$} & \grntxt{$+0.9$} \\
\midrule
DeiT-S & \xmark & $75.3\pm0.4$ & $91.1\pm0.2$ & $94.8\pm0.4$ & $89.2\pm0.2$ & $92.4\pm0.2$ \\
DeiT-S & \cmark & $76.8\pm0.8$ & $91.9\pm0.2$ & $95.2\pm0.3$ & $89.1\pm0.2$ & $92.3\pm0.4$ \\
& & \grntxt{$+1.5$} & \grntxt{$+0.8$} & \grntxt{$+0.4$} & \gtxt{$-0.1$} & \gtxt{$-0.1$} \\
\cmidrule(r){1-1}
DeiT-B & \xmark & $77.0\pm1.2$ & $92.9\pm0.2$ & $96.1\pm0.2$ & $91.2\pm0.1$ & $93.3\pm0.4$ \\
DeiT-B & \cmark & $79.3\pm0.3$ & $93.1\pm0.1$ & $96.4\pm0.2$ & $91.3\pm0.1$ & $93.3\pm0.1$ \\
& & \grntxt{$+2.3$} & \gtxt{$+0.2$} & \grntxt{$+0.3$} & \gtxt{$+0.1$} & \gtxt{$\pm0.0$} \\
\cmidrule(r){1-1}
DeiT-L & \xmark & $72.8\pm5.5$ & $92.8\pm1.0$ & $95.8\pm1.5$ & $90.5\pm2.6$ & $92.4\pm2.0$ \\
DeiT-L & \cmark & $78.8\pm0.8$ & $93.8\pm0.2$ & $97.0\pm0.2$ & $92.0\pm0.2$ & $93.5\pm0.2$ \\
& & \grntxt{$+6.0$} & \grntxt{$+1.0$} & \grntxt{$+1.2$} & \grntxt{$+1.5$} & \grntxt{$+1.1$} \\
\midrule
Swin-Ti & \xmark & $77.0\pm0.1$ & $91.3\pm0.6$ & $95.9\pm0.1$ & $90.0\pm0.2$ & $94.2\pm0.1$ \\
Swin-Ti & \cmark & $81.1\pm0.8$ & $92.8\pm0.4$ & $96.2\pm0.1$ & $90.4\pm0.3$ & $94.8\pm0.5$ \\
& & \grntxt{$+4.1$} & \grntxt{$+2.5$} & \grntxt{$+0.3$} & \grntxt{$+0.4$} & \grntxt{$+0.6$} \\
\cmidrule(r){1-1}
Swin-S & \xmark & $75.7\pm1.4$ & $91.0\pm0.3$ & $95.9\pm0.5$ & $91.1\pm0.2$ & $94.4\pm0.1$ \\
Swin-S & \cmark & $81.4\pm0.2$ & $93.1\pm0.2$ & $96.3\pm0.3$ & $91.2\pm0.2$ & $94.9\pm0.3$ \\
& & \grntxt{$+5.7$} & \grntxt{$+2.1$} & \grntxt{$+1.4$} & \gtxt{$+0.1$} & \grntxt{$+0.5$} \\
\midrule
ResNet-50 & \xmark & $78.2\pm0.5$ & $89.8\pm0.2$ & $91.7\pm0.4$ & $84.4\pm0.2$ & $93.7\pm0.3$ \\
ResNet-50 & \cmark & $80.3\pm0.4$ & $90.4\pm0.2$ & $91.7\pm0.2$ & $84.5\pm0.2$ & $93.7\pm0.3$ \\
& & \grntxt{$+2.1$} & \grntxt{$+0.6$} & \gtxt{$\pm0.0$} & \gtxt{$+0.1$} & \gtxt{$\pm0.0$} \\
\cmidrule(r){1-1}
ResNet-101 & \xmark & $78.4\pm0.6$ & $90.3\pm0.1$ & $91.2\pm0.5$ & $86.0\pm0.2$ & $94.3\pm0.2$ \\
ResNet-101 & \cmark & $81.4\pm0.5$ & $91.3\pm0.1$ & $92.9\pm0.2$ & $86.3\pm0.1$ & $94.0\pm0.3$ \\
& & \grntxt{$+3.0$} & \grntxt{$+1.3$} & \grntxt{$+1.7$} & \grntxt{$+0.3$} & \textcolor{red}{$-0.3$} \\
\bottomrule
\end{tabular}}
\end{table}
\textbf{Downstream tasks.} To assess the transferability of \schemename-trained models, we finetune models pretrained on ImageNet with and without \schemename on five fine-grained datasets:
FGVC-Aircraft \cite{Maji2013}, Stanford Cars~\cite{Dehghan2017}, Oxford Flowers \cite{Nilsback2008}, Food-101 \cite{Kaur2017}, and Oxford-IIIT Pets \cite{Parkhi2012}.
% While for ResNets, the performance of both training datasets is about the same,
In \Cref{tab:downstream-results} we see transformer accuracies improve on all these datasets by up to 7.3 p.p.
% and a reduction of error rate of up to $39.3\%$.
% Notably, training with \name increases the downstream performance of DeiT-S and DeiT-B, even though the ImageNet results were the same.
% This demonstrates that the improved representations from training on \name translate to superior performance beyond gains from better ImageNet performance.
Notably, training with \schemename boosts the downstream performance of DeiT-S and DeiT-B, despite similar ImageNet results.
This shows the improved representations from training with \schemename translate to gains beyond better ImageNet scores.
% not only on ImageNet, but also on fine-grained image classification tasks.
\subsection{Bias and Robustness Evaluation}
% Additional to just using \name for training, its special properties and posibilities for adjustment of the data distribution make it a valuable tool for evaluating other model properties and biases.
Beyond its use for training, \schemename's unique properties and controlled data generation capabilities make it a powerful tool for analyzing behavior and biases of black-box models.
\begin{figure*}
\centering
\includegraphics[width=.95\textwidth]{img/bg_robustness.pdf}
\caption{Evaluation of background robustness on ImageNet + \schemename, ImageNet9 and CounterAnimal.
We plot the in-distribution (top of arrow) and the out-of-distribution (bottom of arrow) accuracy when training with and without \schemename.
We annotate each arrow with its length $\Delta$.
Training with \schemename improves the background robustness of all transformers by mostly boosting the out-of-distribution accuracy.
}
\label{fig:background-robustness}
\end{figure*}
\textbf{Background Robustness.}
% By adjusting the background distribution from using a background from an image of the same class as the foreground to using any background, we can evaluate the robustness of models to shifts in the background distribution.
% We assess background robustness by changing the background distribution, comparing accuracy with backgrounds of the same class as the foreground to using any background.
We assess the robustness of models to shifts in the background distribution from a class-related background to any background.
% We define the background robustness coefficient to be the accuracy of a model on \name when using the same class background divided by the accuracy when using any background:
Background robustness is defined to be the ratio of accuracy on \name with same-class backgrounds to accuracy with any background:
\begin{align}
\text{Background Robustness} = \frac{\text{Acc}(\name_\text{all})}{\text{Acc}(\name_\text{same})}
\end{align}
It represents the relative drop in performance under a background distribution shift.
\Cref{tab:background-robustness} presents the background robustness of various models.
When trained on ImageNet, smaller models generally exhibit greater robustness to changes in the background distribution than larger models and ResNet is more robust than the tested Transformer models.
Crucially, training on \name instead of ImageNet improves the background robustness of all models to $\approx1.00$, meaning that these models are agnostic to the choice of background and only classify based on the foreground.
These findings highlight the generalization benefits of \name.
% Background robustness is defined to be the ratio of accuracy on \name with same-class backgrounds to accuracy with any background:
% \begin{align}
% \text{Background Robustness} = \frac{\text{Acc}(\name_\text{all})}{\text{Acc}(\name_\text{same})}
% \end{align}
% It represents the relative drop in performance under a background distribution shift.
\Cref{fig:background-robustness} presents the background robustness results for three datasets: ImageNet with \schemename (all backgrounds vs. backgrounds of same class), ImageNet9 \cite{Xiao2020} (random backgrounds vs. original backgrounds), and CounterAnimal \cite{Wang2024f} (counter vs. common background).
The top triangle of each arrow represents the in-distribution backgrounds and the bottom triangle represents the out-of-distribution ones.
We follow ImageNet9 and CounterAnimal and assess the background robustness in terms of the accuracy gap when evaluating a model on images of normal background distribution compared to out-of-distribution backgrounds (length of each arrow; $\Delta$).
% When trained on ImageNet, smaller models generally exhibit greater robustness to changes in the background distribution than larger models and ResNet is more robust than the tested Transformer models.
Crucially, \schemename improves the background robustness of all models and across datasets, reducing the background-gap by boosting the performance on the out-of-background-distribution samples more than the in-distribution ones.
% to $\approx1.00$, meaning that these models are agnostic to the choice of background and only classify based on the foreground.
These findings highlight the generalization benefits of \schemename to unusual image compositions.
\paragraph*{Foreground Focus}
\begin{table}
\begin{figure*}
\centering
\resizebox{\columnwidth}{!}{
\begin{tabular}{lcccccc}
\toprule
\multirow{4}{*}{Model} & \multicolumn{6}{c}{Foreground Focus when trained on} \\
\cmidrule(l){2-7}
& IN & FN & IN & FN & IN & FN \\
\cmidrule(lr){2-3} \cmidrule(lr){4-5} \cmidrule(l){6-7}
& \multicolumn{2}{c}{GradCam} & \multicolumn{2}{c}{GradCam++} & \multicolumn{2}{c}{IG} \\
\midrule
ViT-S & $1.2\pm0.1$ & $2.3\pm0.3$ & $1.2\pm0.1$ & $2.1\pm0.4$ & $1.9\pm0.1$ & $2.7\pm0.1$ \\
ViT-B & $1.2\pm0.1$ & $2.4\pm0.7$ & $1.1\pm0.1$ & $2.1\pm0.1$ & $1.7\pm0.1$ & $2.7\pm0.1$ \\
ViT-L & $1.3\pm0.1$ & $1.6\pm0.1$ & $1.1\pm0.1$ & $1.3\pm0.1$ & $1.3\pm0.1$ & $2.6\pm0.1$ \\
\midrule
Swin-Ti & $0.9\pm0.1$ & $0.7\pm0.1$ & $1.0\pm0.3$ & $0.7\pm0.3$ & $2.5\pm01$ & $4.8\pm0.3$ \\
Swin-S & $0.8\pm0.1$ & $0.7\pm0.1$ & $0.7\pm0.1$ & $0.7\pm0.4$ & $2.4\pm0.1$ & $4.6\pm0.3$ \\
\midrule
ResNet-50 & $2.2\pm0.1$ & $2.7\pm0.1$ & $2.0\pm0.1$ & $2.9\pm0.1$ & $3.2\pm0.1$ & $4.9\pm0.2$ \\
ResNet-101 & $2.3\pm0.1$ & $2.8\pm0.1$ & $2.2\pm0.1$ & $3.0\pm0.1$ & $3.2\pm0.1$ & $4.8\pm0.1$ \\
\bottomrule
\end{tabular}}
\caption{Evaluation of the foreground focus using GradCam, GradCam++ and IntegratedGradients of models trained on \name (FN) and on ImageNet (IN) directly. Training on \name improves the foreground focus of almost all models.}
\label{tab:foreground-focus}
\end{table}
\includegraphics[width=.95\textwidth]{img/fg_focus.pdf}
\caption{Evaluation of the foreground focus (\Cref{eq:fg-focus}) using GradCam, GradCam++ and IntegratedGradients (IG) of models trained on ImageNet. Training with \schemename improves the foreground focus of almost all models.}
\label{fig:foreground-focus}
\end{figure*}
Leveraging our inherent knowledge of the foreground masks when using \name, as well as common XAI techniques~\cite{Selvaraju2016,Chattopadhay2018,Sundararajan2017}, we can evaluate a model's focus on the foreground object.
We can directly evaluate ImageNet trained models, but this technique can also be extended to other datasets without relying on manually annotated foreground-masks.
To evaluate the foreground focus, we employ Grad-CAM \cite{Selvaraju2016}, Grad-CAM++ \cite{Chattopadhay2018} or IntegratedGradients (IG) \cite{Sundararajan2017} to compute the per-pixel importance of an image for the model's prediction.
\textbf{Foreground Focus.}
Leveraging our inherent knowledge of the foreground masks when using \schemename, as well as common XAI techniques~\cite{Selvaraju2016,Chattopadhay2018,Sundararajan2017}, we can evaluate a model's focus on the foreground object.
% I.e. we measure how much the model's decision depends on the foreground.
We can directly evaluate ImageNet-trained models, but this technique can also be extended to other datasets without relying on manually annotated foreground masks.
To evaluate the foreground focus, we employ Grad-CAM \cite{Selvaraju2016}, Grad-CAM++ \cite{Chattopadhay2018} and IntegratedGradients (IG) \cite{Sundararajan2017} to compute the per-pixel importance of an image for the model's prediction.
The foreground focus is defined to be the ratio of the foreground's relative importance to its relative size in the image:
\begin{align}
\begin{align} \label{eq:fg-focus}
\text{FG Focus}(\text{img}) = \frac{\text{Area}(\text{img}) \hspace{3pt} \text{Importance}(\text{fg})}{\text{Area}(\text{fg}) \hspace{3pt} \text{Importance}(\text{img})}
\end{align}
The foreground focus of a model is its average foreground focus over all test images.
\Cref{tab:foreground-focus} presents our findings.
Training on \name significantly increasees the foreground focus of ViT and ResNet across all metrics used.
For Swin, the foreground focus stagnates when measured using GradCam and GradCam++, but almost doubles when using IG.
If all pixels uniformly receive the same importance value, the foreground focus is one.
The foreground focus of a model is its average focus over all test images.
\Cref{fig:foreground-focus} presents our findings.
Using \schemename significantly increases the foreground focus of ViT, DeiT and ResNet across all XAI metrics.
% I.e. \schemename-trained models base their decision more on the foreground object compared to the background than models trained without \schemename.
% For Swin, the foreground focus stagnates when measured using GradCam and GradCam++, but almost doubles when using IG.
% We hypothesize that Swin's below-uniform foreground focus reported with GradCam is due to its specific implementation for Swin.
We hypothesize Swin's below-uniform foreground focus with GradCam is due to its specific implementation.
% These differences might be due to the way GradCam is calculated for Swin \todo{cite package website where this is from} and the \todo{common critique of GradCam}.
\paragraph*{Center Bias}
\begin{table}
\begin{table}[t]
\caption{
% Evaluation of the center bias.
Accuracy relative to the center accuracy of multiple instantiations of the models when the foreground objects is in different cells of a $3 \times 3$ grid.
We calculate center bias according to \Cref{eq:center-bias}.
Using \schemename significantly reduces models' center bias.}
\label{tab:center-bias}
\centering
\resizebox{\columnwidth}{!}{
\resizebox{.78\columnwidth}{!}{
\begin{tabular}{lccc}
\toprule
\multirow{2.5}{*}{Model} & \multicolumn{2}{c}{\makecell{Center Bias when trained on}} & \multirow{2.5}{*}{Delta} \\
\multirow{2.5}{*}{Model} & \multicolumn{2}{c}{\makecell{Center Bias [\%] when trained}} & \multirow{2.5}{*}{Delta} \\
\cmidrule(lr){2-3}
& ImageNet & \name \\
& w/o \schemename & w/ \schemename \\
\midrule
ViT-S & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/ViT-S_ImageNet_v1.pdf} \includegraphics[width=.08\columnwidth]{img/ViT-S_ImageNet_v2.pdf} \includegraphics[width=.08\columnwidth]{img/ViT-S_ImageNet_v3.pdf}} & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/ViT-S_RecombNetAll_v1.pdf} \includegraphics[width=.08\columnwidth]{img/ViT-S_RecombNetAll_v2.pdf} \includegraphics[width=.08\columnwidth]{img/ViT-S_RecombNetAll_v3.pdf}} \\
& $0.255\pm0.008$ & $0.220\pm003$ & \grntxt{-0.035} \\
ViT-B & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/ViT-B_ImageNet_v1.pdf} \includegraphics[width=.08\columnwidth]{img/ViT-B_ImageNet_v2.pdf} \includegraphics[width=.08\columnwidth]{img/ViT-B_ImageNet_v3.pdf}} & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/ViT-B_RecombNetAll_v1.pdf} \includegraphics[width=.08\columnwidth]{img/ViT-B_RecombNetAll_v2.pdf} \includegraphics[width=.08\columnwidth]{img/ViT-B_RecombNetAll_v3.pdf}} \\
& $0.254\pm0.004$ & $0.190\pm0.002$ & \grntxt{-0.064} \\
ViT-L & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/ViT-L_ImageNet_v1.pdf} \includegraphics[width=.08\columnwidth]{img/ViT-L_ImageNet_v2.pdf} \includegraphics[width=.08\columnwidth]{img/ViT-L_ImageNet_v3.pdf}} & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/ViT-L_RecombNetAll_v1.pdf} \includegraphics[width=.08\columnwidth]{img/ViT-L_RecombNetAll_v2.pdf} \includegraphics[width=.08\columnwidth]{img/ViT-L_RecombNetAll_v3.pdf}} \\
& $0.243\pm0.011$ & $0.117\pm0.007$ & \grntxt{-0.126} \\
ViT-S & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/ViT-S_ImageNet_v1.pdf} \includegraphics[width=.08\columnwidth]{img/ViT-S_ImageNet_v2.pdf} \includegraphics[width=.08\columnwidth]{img/ViT-S_ImageNet_v3.pdf}} & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/ViT-S_RecombNet_all_v1.pdf} \includegraphics[width=.08\columnwidth]{img/ViT-S_RecombNet_all_v2.pdf} \includegraphics[width=.08\columnwidth]{img/ViT-S_RecombNet_all_v3.pdf}} \\
& $25.5\pm0.8$ & $22.0\pm0.3$ & \grntxt{$-3.5$} \\
ViT-B & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/ViT-B_ImageNet_v1.pdf} \includegraphics[width=.08\columnwidth]{img/ViT-B_ImageNet_v2.pdf} \includegraphics[width=.08\columnwidth]{img/ViT-B_ImageNet_v3.pdf}} & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/ViT-B_RecombNet_all_v1.pdf} \includegraphics[width=.08\columnwidth]{img/ViT-B_RecombNet_all_v2.pdf} \includegraphics[width=.08\columnwidth]{img/ViT-B_RecombNet_all_v3.pdf}} \\
& $25.4\pm0.4$ & $19.0\pm0.2$ & \grntxt{$-6.4$} \\
ViT-L & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/ViT-L_ImageNet_v1.pdf} \includegraphics[width=.08\columnwidth]{img/ViT-L_ImageNet_v2.pdf} \includegraphics[width=.08\columnwidth]{img/ViT-L_ImageNet_v3.pdf}} & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/ViT-L_RecombNet_all_v1.pdf} \includegraphics[width=.08\columnwidth]{img/ViT-L_RecombNet_all_v2.pdf} \includegraphics[width=.08\columnwidth]{img/ViT-L_RecombNet_all_v3.pdf}} \\
& $24.3\pm1.1$ & $11.7\pm0.7$ & \grntxt{$-12.6$} \\
\midrule
Swin-Ti & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/Swin-Ti_ImageNet_v1.pdf} \includegraphics[width=.08\columnwidth]{img/Swin-Ti_ImageNet_v2.pdf} \includegraphics[width=.08\columnwidth]{img/Swin-Ti_ImageNet_v3.pdf}} & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/Swin-Ti_RecombNetAll_v1.pdf} \includegraphics[width=.08\columnwidth]{img/Swin-Ti_RecombNetAll_v2.pdf} \includegraphics[width=.08\columnwidth]{img/Swin-Ti_RecombNetAll_v3.pdf}} \\
& $0.250\pm0.007$ & $0.165\pm0.002$ & \grntxt{-0.085} \\
Swin-S & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/Swin-S_ImageNet_v1.pdf} \includegraphics[width=.08\columnwidth]{img/Swin-S_ImageNet_v2.pdf} \includegraphics[width=.08\columnwidth]{img/Swin-S_ImageNet_v3.pdf}} & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/Swin-S_RecombNetAll_v1.pdf} \includegraphics[width=.08\columnwidth]{img/Swin-S_RecombNetAll_v2.pdf} \includegraphics[width=.08\columnwidth]{img/Swin-S_RecombNetAll_v3.pdf}} \\
& $0.232\pm0.001$ & $0.156\pm002$ & \grntxt{-0.076} \\
DeiT-S & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/DeiT-S_ImageNet_vNone.pdf} \includegraphics[width=.08\columnwidth]{img/DeiT-S_ImageNet_v2.pdf} \includegraphics[width=.08\columnwidth]{img/DeiT-S_ImageNet_v3.pdf} } & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/DeiT-S_fornet_all_linear_v1.pdf} \includegraphics[width=.08\columnwidth]{img/DeiT-S_fornet_all_linear_v2.pdf} \includegraphics[width=.08\columnwidth]{img/DeiT-S_fornet_all_linear_v3.pdf}} \\
& $20.4 \pm 0.2$ & $21.2 \pm 0.1$ & \gtxt{$+0.8$} \\
DeiT-B & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/DeiT-B_ImageNet_vNone.pdf} \includegraphics[width=.08\columnwidth]{img/DeiT-B_ImageNet_v2.pdf} \includegraphics[width=.08\columnwidth]{img/DeiT-B_ImageNet_v3.pdf} } & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/DeiT-B_fornet_all_cos_v1.pdf} \includegraphics[width=.08\columnwidth]{img/DeiT-B_fornet_all_cos_v2.pdf} \includegraphics[width=.08\columnwidth]{img/DeiT-B_fornet_all_cos_v3.pdf}} \\
& $19.0 \pm 0.7$ & $19.0 \pm 0.2$ & \gtxt{$\pm0.0$} \\
DeiT-L & \raisebox{-6pt}{ \includegraphics[width=.08\columnwidth]{img/DeiT-L_ImageNet_v1.pdf} \includegraphics[width=.08\columnwidth]{img/DeiT-L_ImageNet_v2.pdf} \includegraphics[width=.08\columnwidth]{img/DeiT-L_ImageNet_v3.pdf} } & \raisebox{-6pt}{ \includegraphics[width=.08\columnwidth]{img/DeiT-L_fornet_all_cos_v1.pdf} \includegraphics[width=.08\columnwidth]{img/DeiT-L_fornet_all_cos_v2.pdf} \includegraphics[width=.08\columnwidth]{img/DeiT-L_fornet_all_cos_v3.pdf} } \\
& $21.2 \pm 0.2$ & $18.0 \pm 0.2$ & \grntxt{$-3.2$} \\
\midrule
ResNet50 & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/ResNet50_ImageNet_v1.pdf} \includegraphics[width=.08\columnwidth]{img/ResNet50_ImageNet_v2.pdf} \includegraphics[width=.08\columnwidth]{img/ResNet50_ImageNet_v3.pdf}} & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/ResNet50_RecombNetAll_v1.pdf} \includegraphics[width=.08\columnwidth]{img/ResNet50_RecombNetAll_v2.pdf} \includegraphics[width=.08\columnwidth]{img/ResNet50_RecombNetAll_v3.pdf}} \\
& $0.263\pm0.003$ & $0.197\pm0.003$ & \grntxt{-0.066} \\
ResNet101 & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/ResNet101_ImageNet_v1.pdf} \includegraphics[width=.08\columnwidth]{img/ResNet101_ImageNet_v2.pdf} \includegraphics[width=.08\columnwidth]{img/ResNet101_ImageNet_v3.pdf}} & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/ResNet101_RecombNetAll_v1.pdf} \includegraphics[width=.08\columnwidth]{img/ResNet101_RecombNetAll_v2.pdf} \includegraphics[width=.08\columnwidth]{img/ResNet101_RecombNetAll_v3.pdf}} \\
& $0.230\pm0.003$ & $0.199\pm002$ & \grntxt{-0.031} \\
Swin-Ti & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/Swin-Ti_ImageNet_v1.pdf} \includegraphics[width=.08\columnwidth]{img/Swin-Ti_ImageNet_v2.pdf} \includegraphics[width=.08\columnwidth]{img/Swin-Ti_ImageNet_v3.pdf}} & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/Swin-Ti_RecombNet_all_v1.pdf} \includegraphics[width=.08\columnwidth]{img/Swin-Ti_RecombNet_all_v2.pdf} \includegraphics[width=.08\columnwidth]{img/Swin-Ti_RecombNet_all_v3.pdf}} \\
& $25.0\pm0.7$ & $16.5\pm0.2$ & \grntxt{$-8.5$} \\
Swin-S & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/Swin-S_ImageNet_v1.pdf} \includegraphics[width=.08\columnwidth]{img/Swin-S_ImageNet_v2.pdf} \includegraphics[width=.08\columnwidth]{img/Swin-S_ImageNet_v3.pdf}} & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/Swin-S_RecombNet_all_v1.pdf} \includegraphics[width=.08\columnwidth]{img/Swin-S_RecombNet_all_v2.pdf} \includegraphics[width=.08\columnwidth]{img/Swin-S_RecombNet_all_v3.pdf}} \\
& $23.2\pm0.1$ & $15.6\pm0.2$ & \grntxt{$-7.6$} \\
\midrule
ResNet50 & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/ResNet50_ImageNet_v1.pdf} \includegraphics[width=.08\columnwidth]{img/ResNet50_ImageNet_v2.pdf} \includegraphics[width=.08\columnwidth]{img/ResNet50_ImageNet_v3.pdf}} & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/ResNet50_RecombNet_all_v1.pdf} \includegraphics[width=.08\columnwidth]{img/ResNet50_RecombNet_all_v2.pdf} \includegraphics[width=.08\columnwidth]{img/ResNet50_RecombNet_all_v3.pdf}} \\
& $26.3\pm0.3$ & $19.7\pm0.3$ & \grntxt{$-6.6$} \\
ResNet101 & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/ResNet101_ImageNet_v1.pdf} \includegraphics[width=.08\columnwidth]{img/ResNet101_ImageNet_v2.pdf} \includegraphics[width=.08\columnwidth]{img/ResNet101_ImageNet_v3.pdf}} & \raisebox{-6pt}{\includegraphics[width=.08\columnwidth]{img/ResNet101_RecombNet_all_v1.pdf} \includegraphics[width=.08\columnwidth]{img/ResNet101_RecombNet_all_v2.pdf} \includegraphics[width=.08\columnwidth]{img/ResNet101_RecombNet_all_v3.pdf}} \\
& $23.0\pm0.3$ & $19.9\pm0.2$ & \grntxt{$-3.1$} \\
\bottomrule
\end{tabular} }
\includegraphics[width=.75\columnwidth]{img/colorbar_horizontal.pdf}
\caption{Evaluation of the position bias. We plot the accuracy relative to the center accuracy of multiple instantiations of the models when the foreground objects is in different cells a $3 \times 3$ grid.
Training on \name significantly reduces a models center bias.}
\label{tab:center-bias}
\includegraphics[width=.8\columnwidth]{img/colorbar_horizontal.pdf}
\end{table}
With \name we have unique control over the position of the foreground object in the image.
This lets us quantify the center bias of ImageNet- and \name-trained models.
We divide the image into a $3 \times 3$ grid and evaluate model accuracy when the foreground object is in each of the $9$ grid cells.
\textbf{Center Bias.}
With \schemename we have unique control over the position of the foreground object in the image.
This lets us quantify the center bias of models trained with and without \schemename.
We divide the image into a $3 \times 3$ grid and evaluate model accuracy when the (scaled-down) foreground object is in each of the $9$ grid cells.
Each cell's accuracy is divided by the accuracy in the center cell for normalization, which gives us the relative performance drop when the foreground is in each part of the image.
The center bias is calculated as one minus the average of the minimum performance of a corner cell and the minimum performance of a side cell:
\begin{align}
\begin{split}
& \text{Center Bias} = \\
& \hspace{7pt} 1 - \frac{\min\limits_{a, b \in \{0, 2\}} \text{Acc}(\text{cell}_{(a, b)}) + \min\limits_{\substack{a=1 \text{ or } b=1 \\ a \neq b}} \text{Acc}(\text{cell}_{(a, b)})}{2 \text{Acc}(\text{cell}_{(1, 1)})}
\end{split}
% \begin{align}
% \begin{split}
% & \text{Center Bias} = \\
% & \hspace{7pt} 1 - \frac{\min\limits_{a, b \in \{0, 2\}} \text{Acc}(\text{cell}_{(a, b)}) + \min\limits_{\substack{a=1 \text{ or } b=1 \\ a \neq b}} \text{Acc}(\text{cell}_{(a, b)})}{2 \text{Acc}(\text{cell}_{(1, 1)})}
% \end{split}
% \end{align}
\begin{align} \label{eq:center-bias}
\text{Center Bias} = 1 - \frac{\min\limits_{c \in \text{sides}} \text{Acc}(c) + \min\limits_{c \in \text{corners}} \text{Acc}(c)}{2 \text{Acc}(c_\text{center})}
\end{align}
\Cref{tab:center-bias} visualizes the center bias of three instantiations of each model.
Performance is generally highest in the center and the center top and bottom and center left and right cells, and lowest in the four corners.
Performance is generally highest in the center and lowest in the four corners.
Interestingly, ImageNet-trained models perform slightly better when the foreground object is on the right side of the image, compared to the left side, despite our use of random flipping with a probability of $0.5$ during training.
% Training on \name reduces the center bias of all models by at least half.
Training on \name significantly reduces center bias across all models.
This demonstrates that \name promotes a more uniform spatial attention distribution.
Their accuracy is higher in the center left and right cells than in the center top and bottom ones, which is not the case for ImageNet-trained models.
Using \schemename significantly reduces center bias across models, with a more uniform performance especially across the middle row.
% Their accuracy is higher in the center left and right cells than in the center top and bottom ones, which is not the case for ImageNet-trained models.
% This demonstrates that \schemename promotes a more uniform spatial attention distribution, counteracting the center-bias of ImageNet.
Thus, \schemename makes the model recognize objects across a wider spatial distribution, counteracting the center-bias of ImageNet.
\paragraph*{Size Bias}
\begin{figure}
\begin{figure}[t!]
\centering
\includegraphics[width=.9\columnwidth]{img/size_bias.pdf}
\caption{Evaluation of the size bias of models trained on \name. We plot the accuracy relative to the accuracy when using the mean foreground size.}
\includegraphics[width=\columnwidth]{img/size_bias_grid.pdf}
\caption{Evaluation of the size bias of models trained on ImageNet. We plot the accuracy relative to the accuracy when using the default size ($f_\text{size} = 1.0$).}
\label{fig:size-bias}
\end{figure}
Finally, we evaluate the impact of different-sized foreground objects on the accuracy.
\textbf{Size Bias.}
Finally, we evaluate the impact of different sized foreground objects on the accuracy.
For this evaluation, we use the \emph{mean} foreground size strategy.
We introduce a size factor $f_\text{size}$ by which we additionally scale the foreground object before pasting it onto the background.
Results are again normalized by the accuracy when using the mean foreground size ($f_\text{size} = 1.0$).
\Cref{fig:size-bias} shows the size bias curves of ViT-S and ViT-B when trained on ImageNet and \name.
Results are normalized by the accuracy when using $f_\text{size} = 1.0$.
\Cref{fig:size-bias} shows the size bias curves of models trained with and without \schemename.
% When training on \name, the resulting model keeps it's good performance on smaller foreground objects, while models trained on ImageNet fall of faster and lower.
Models trained on \name maintain better performance even with smaller foreground objects, when ImageNet-trained models exhibit a more rapid performance decline.
Therefore, \name-training improves robustness to variations in object scale.
Models trained using \schemename maintain perform better, especially with smaller foreground objects.
%, when ImageNet-trained models exhibit a more rapid performance decline.
Therefore, \schemename-training improves robustness to variations in object scale, especially for larger models.