Photoshop "Export as" quality problem

That's right. Damselflies are smaller, and fold their wings back when resting.

Er...where were we? 😉

I love the detail @D Fosse, and it's a fantastic photo — but I didn't notice how narrow the body was because of the crop. I was wrong to call it a dragonfly — it's a damselfly.

https://british-dragonflies.org.uk/species/large-red-damselfly/

Jane

No, you probably wouldn't, @jane-e . It's a European species known as Pyrrhosoma nymphula, no less. Not my area of expertise, but I always make it a point to know exactly what I have photographed. Most of our native species are bright blue, this is the only red one. It's actually a very tight crop, but shot on a Sony a7r-series camera, so there's lots of pixels to go around 😉

Nice dragonfly close-ups, @D Fosse ! What kind of dragonfly is it? I don't think I've seen that one before.

Jane

I am absolutely unable to reproduce this.

Save For Web and Export produce identical results when all else is equal.

These are 100% crop screenshots from the 1920 x 1080 test jpegs:

When overlaid in Difference blend mode, and an extreme Curves layer to bring out every tiny bit of difference, all I get is general noise indicating that they are different jpeg encoding engines, but produce the same result:

Note that the "difference" pixels here are only two or three RGB values apart, not so much that you actually see that. And remember, this is jpeg, so values will be altered.

In short, I can't see any bug here. I never use Export because of its still broken color management, but quality-wise they're the same.

I can't always use Save for web (Legacy) because sometimes I need using artboards.

By @Payne66

Do you know of the File > Export > Artboards to Files script?

A custom script could also be created to use your preferred Save for Web (Legacy) settings and export the artboards.

Can you provide a sample for testing of the original 4400 x 2475 image of the book page?

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I starting believe that this is some kind of bug.

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The two methods use different underlying technology. Export As is meant as a replacement for Save for Web (Legacy), and despite offering some advancements, many find it to be a downgrade, not an upgrade.

1920 x 1080 (downscale from 4400 x 2475 - 72 ppi). Bicubic Automatic resample. Jpeg maximum quality.

The problem is why Save for web (Legacy) can do it beutifully but newer Export as can't with the same export setting.

What are the pixel dimensions? Which resampling algorithm? What is the jpeg compression level?