feat(server): optimize person thumbnail generation

[mertalev]

trafficstars

Description

Person thumbnails are currently generated by cropping to a buffer and passing this buffer to sharp to resize. This is inefficient:

1. It ends up generating two thumbnails instead of one (the buffer is implicitly a new JPEG file)
2. libvips is optimized for longer image processing pipelines, so separating the workload here is worse for performance
3. It lowers quality as person thumbnails are compressed at least three times: once due to the use of the compressed preview image, a second time with the buffer, and a third time with the resize

This PR combines cropping and resizing to the same pipeline for better performance and less compressed thumbnails. Additionally, it uses the original image to generate the thumbnail to further reduce compression artifacts, scaling the bounding box dimensions as needed.

How Has This Been Tested?

I ran facial recognition on all assets and confirmed the person thumbnails are accurately cropped and look normal.

Before:

After:

[cloudflare-workers-and-pages[bot]]

Deploying immich with    Cloudflare Pages

Latest commit:	0309ad1
Status:	✅  Deploy successful!
Preview URL:	https://e0654264.immich.pages.dev
Branch Preview URL:	https://feat-optimize-thumbnail-gene.immich.pages.dev

View logs

[alextran1502]

I tested with a new instance, and the facial thumbnail crop is off

I also got some errors due to bad dimensions.

[mertalev]

Hmm that's weird, it was working well when I tested it. I'll do more testing tomorrow

[mertalev]

@alextran1502 Can you confirm if you still have the issue as of the latest commit? I'm wondering if you maybe tried it with an older commit

[alextran1502]

@alextran1502 Can you confirm if you still have the issue as of the latest commit? I'm wondering if you maybe tried it with an older commit

I will take a look again and report back

[mertalev]

I tried on a slice of my library and reproduced the issue. I think it's because of #3569.

[mertalev]

Can confirm that handling orientation fixed all the bad crops.

[mertalev]

@alextran1502 Could you test this PR when you get a chance? I want to be sure the cropping issues you noticed are fixed now.

[alextran1502]

Great work! Thank you for the discovery and the fix!