vae tiling improvements: encoding support and adaptative overlap

[stduhpf]

• Added a boolean argument sd_tiling() function, specifying if the output tile is scaled up (for decoding) or if the input is (encoding).
• Added a mechanism to automatically fix the tile overlaps in cases of mismatch between image size and tile size.

With these changes, vae encoding can now be tiled, and a small (unreported?) issue with the upscaler (or tae) over-brightening some parts of the image is now fixed. This could also be a step toward tiled diffusion support.

Fixes #588 and #564

[Green-Sky]

• Added a mechanism to automatically fix the tile overlaps in cases of mismatch between image size and tile size.

With these changes, vae encoding can now be tiled, and a small (unreported?) issue with the upscaler over-brightening some parts of the image is now fixed. This could also be a step toward tiled diffusion support.

Nice! It would also be interesting to see larger tile sizes. Depending on VAE, larger tiles would still fit into the memory budget and would speed things up.

[masamaru-san]

I am not familiar with AI programming, and this is a machine translation, so please ignore me if I say something strange.

The last_x used in the loop at line 568 (or line 629 in this PR) in ggml_extend.hpp is only initialized outside the loop.
Locally, it seems that this PR with initializing last_x = false; before the for (int x = 0; ~ loop would improve the generation results.

However, the brightness issue (issue #588) seems to remain.

[stduhpf]

The last_x used in the loop at line 568 (or line 629 in this PR) in ggml_extend.hpp is only initialized outside the loop.
Locally, it seems that this PR with initializing last_x = false; before the for (int x = 0; ~ loop would improve the generation results.

I'm sorry, I don't quite understand what you mean. last_x is already set to false when the loop starts.

However, the brightness issue (issue #588) seems to remain.

You mean this PR doesn't fix it for you? If so this is strange, I can't reproduce the issue with this PR...

master	PR

As you can see the image made with the master branch is much brighter than the one with this PR.
(ignore the slight variation of the composition, it's just a little unrelated bug of the vulkan backend that happens at non standard resolutions, that's fixed by updating GGML)