bug fix: concat along the batch dimension

[jonbakerfish]

concat the img_list along the batch dimension for better visualization when the number of images is more than 4.

[LeoXing1996]

Thank you for your interest in our project.

In the current version, MMGenVisualizationHook or VisualizationHook is only used in translation models, SinGAN and DDPM, and both these models visualize less than or equal to 4 images.

You may use VisualizeUnconditionalSamples if you want to modify the output shape of visualization results.

You may open an issue and explain your usage scenarios if VisualizeUnconditionalSamples can't meet your usage needs.

[jonbakerfish]

Hi @LeoXing1996 , this hook is used in cyclegan with an option res_name_list specifying the order of the images to be collected. Besides changing the concat dimension to 0 is more flexible for the downstream make_grid IMHO.

[LeoXing1996]

Can you provide some visualization comparison results?

[jonbakerfish]

E.g., given 8 images with shape HxW, the current implementation will generate a long Hx(8W) image, and the nrow is not used.
If concat along dim=0 and setting nrow=4, this will generate a (2H x 4*W) image.