P: New Photoshop webp save-as copy - Webp images too saturated

[paull92729451]

Photoshop's new webp support under save-as copy produces images that are over saturated compared with the original in photoshop, and when compared to exported jpg files. More compressed webp files have more excess saturation. See attached screenshot (I was unable to upload the webp image itself, as this Adobe Support page does not accept webp uploads). The webp image is also visibly more saturated when re-opened in photoshop. in the image below, the JPG file looks identical to the original image in Photoshop, as expected.

• Photoshop version 23.2.1
• Windows 10 21H1

Open colour photograph in Photoshop (in my case the original was an 8-bit psd). Choose Save As Copy and choose Webp, choose 50% compression and save. re-open in photoshop or any colour managed software of your choice (I used a colour managed Irfanview) and compare that side by side with the original image in photoshop. The webp version will have more saturation than the original photoshop photoshop image.

Expected result: the webp version should show the same level of saturation and colour values to the original photoshop image.

[J453]

Hmm. Seems to be coming out the same for me:

I even did a difference layer and they came out the same.

[paull92729451]

Hi Jeffrey,

There seems to be a bug that leaves me unable to reply in a browser - I've tried 3 of them, all logged in to my account, but clicking "Reply" on the post does nothing.

So, I can't include the images of my histograms that show the shift to the right in magenta for the 50% compressed webp image. It also shows visible outlines when I choose Difference blend mode. I did the same with JPG (100% & 50% quality) and the 50% quality also showed outlines in Difference blend mode. The outlines in Difference blend mode for each 50% image is to be expected because of compression artifacts, but there was no shift to the right in the histogram for magenta or for any colour with the 50% jpg image, though there was a very slight vertical shift in the histogram.

If I can eventually reply on the website I'll post images of the histograms.

Paul

[TPinkerton]

Hi Paul,

I wonder if color profiles could somehow be involved? What is the color profile associated with your original file? When you save the WebP file, are you including the color profile (have the "Embed Color Profile" checkbox 'on')? What is your default RGB working space?

Tom

[paull92729451]

Hi Tom,

(I still can't reply to the forum directly, so can't include images) The colour profile is sRGB IEC61966-2.1in the PSD, and that was embedded in the webp saved file. My default RGB working space is sRGB IEC61966-2.1.

I wish I could post directly to the forum, as I'd like to show you the histogram shift. I have no idea why it used to work (even as recently as me starting this thread) and now doesn't.

P

[TPinkerton]

Thanks, Paul. I think I'm now seeing the color balance shifts with some images (toward magenta) that you're seeing. We'll start looking into this right away. Something is going awry at the compression stage of the encoding process.

I wish I could help with the direct forum replies, but that's unfortunately outside my area of expertise. If you can get that resolved and are able to resume posting files, I'd love to try and get a copy of the original image you used for your comparison. I'm using a cropped version of your comparison file and can see the magenta shift when I resave that using WebP, but it's very subtle. I suspect that using the full resolution version would show a more dramatic shift.

[paull92729451]

Hi Tom,

Hopefully it will be an easy fix, and thanks for following up on it. I'll DM you about the original image I'm using.

Paul

[ProDesignTools]

I just discovered the same thing. I was saving a WebP image for the first time natively in Photoshop, and coincidentally it just happened to have a background gradient of magenta (#d91473) to purple (#452769). And I noticed that Photoshop's native WebP output came out noticibly dimmer than the JPG version...

I went back and reinstalled the WebPShop plugin on the latest PS release – and its WebP results are equivalent to the JPG. So, Photoshop is close but seems there could be a glitch here.

[TPinkerton]

Update: We've discovered the problem, and a fix is in progress. We'll get this into a maintenance release as soon as possible. Thanks for all your help with diagnosing this.

[paull92729451]

that's excellent news. thanks very much for following up on it so swiftly.

P

[TPinkerton]

The fix for this problem should now be included with the latest Photoshop update, Photoshop version 23.4.0.

[TPinkerton]

So that update appears to have been put on hold. Apologies for jumping the gun. In any case, the fix for this problem will be included with the next update.

[paull92729451]

Hi Tom,

Thanks for letting me know. I'm looking forward to the fix arriving.

Paul