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Over-exposed parts of generated images at some resolutions with VAE (or TAE) tiling, and upscaler #588
Description
I noticed this problem some time ago, But I forgot to make an issue about it. It's very noticable with Tiled TAESD and with upscaler, not as much with tiled VAE.
It happens with tiled VAE when the resolution isn't a multiple of 128 in both dimensions, with tiled TAEsd when the resolution isn't a multiple of 256 in both dimensions, and with the upscaler when the resolution isn't a multiple of 512 in both dimensions. (so 4x the tile size?)
Example:
- SD1.x, 512x576 resolution : both tiled autoencoders and upscaler are broken
| VAE | Tiled VAE | TAESD | Tiled TAESD |
|---|---|---|---|
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 |
 |
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| VAE + upscaler |
|---|
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- SD1.x, 512x640 resolution : only tiled taesd and upscaler are broken
| VAE | Tiled VAE | TAESD | Tiled TAESD |
|---|---|---|---|
 |
 |
 |
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| VAE + upscaler |
|---|
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- SD1.x, 512x768 resolution : only upscaler is broken
| VAE | Tiled VAE | TAESD | Tiled TAESD |
|---|---|---|---|
 |
 |
 |
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| VAE + upscaler |
|---|
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(I swear it's using the exact same prompt as the other examples)
- SD1.x, 512x512 resolution: control, everything is fine
| VAE | Tiled VAE | TAESD | Tiled TAESD |
|---|---|---|---|
 |
 |
 |
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| VAE + upscaler |
|---|
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Activity
[-]Over-exposed images at some resolutions with VAE (or TAE) tiling, and upscaler[/-][+]Over-exposed parts of generated images at some resolutions with VAE (or TAE) tiling, and upscaler[/+]FSSRepo commentedon Feb 8, 2025
It is normal since SD 1.5 does not support resolutions that are not multiples of 2, and as long as one side of the image is 512, there is no problem. 512x512, 512x768, and 768x512 are the resolutions it handles without generating a lot of artifacts or aberrations.
stduhpf commentedon Feb 8, 2025
It's not really about the quality of the generated image, it's something that only happens when using tiling, regardless of the model used. VAE without tiling is working regardless of the resolution.
For example this still happens with sd3.5 medium or flux, even though those models support arbitrary resolutions. I only used SD1.5 (dreamshaper 8 LCM to be exact) because it was faster to generate all the example images with it.
Also the upscaler still has the issue with 512x768 input resolution.
merged leejet/stable-diffusion.cpp#588 to fix vae tiling, ref #1603