Image preview

[stduhpf]

Forked off #454
Would also probably replace #416

• Move the preview decoding logic from examples/cli/main.cpp to stable-diffusion.cpp
• Image preview is disabled by default
• Adds possibility to chose between previewing image with latent projection (as demonstrated in fast latent image preview #454), TAE, or VAE
• Adds possibility to load TAE for preview only (decode final image with VAE)
• Default image preview path is preview.png

Related to #354, if the user uses an image viewer that updates its render when the image file changes, then it's possible to see the progress in real time.

[wandbrandon]

+1 for this in main, great work!

[phil2sat]

I really would like to get this on master, problem i used it a lot but it doesn't build against current master.

[stduhpf]

Thanks for the heads up, I'll try to look into resolving these conflicts this week.

[stduhpf]

@phil2sat it builds now. I have only tried with sd1.5 so far, but it seems to work fine.

[stduhpf]

Works with qwen image (looks like qwen-image's VAE is almost identical to wan2.1's, not just the architecture, but the latent space too)

[phil2sat]

Can confirm, works. Even with qwen-image.

Huge Problem is progress on master is so fast, i had to manually patch it to merge, only a couple of hours later.

@leejet, please add this feature, its so essential for testing, debugging. On new models, samplers, schedulers i always watch the generation live, so i can exactly see on what step goes something wrong.

Actually i have a problem with qwen-image-edit on ComfyUI. With step-5 something gets weird with my workflow, without preview this is impossible to track.

I know with a 5K $ GPU just wait some seconds, but if every step needs 30s, every preview shows when to abort generation to safe power and time.

[leejet]

When the pending issue is resolved, I will merge this pull request.

[phil2sat]

@leejet, please...