P: New Export As gives bad results for PNG (8-bit) Smaller Size

[Chain83]

The new Export As gives bad results for PNG (8-bit) when reducing the color palette. This is most visible in gradients. Tested on Photoshop v23.0.0 on Windows 10.

Workaround: Enable Legacy Export As in Preferences.

Steps to reproduce problem:

1. Create a new image
2. Make a gradient using the Blue_24 preset (or similar, but that's the one I used).
3. File > Export > Export As...
4. Choose PNG, and "Smaller File (8-bit)"
5. Result: You get a few lines through the gradient that are too bright or dark. Not good.
6. Result if using Legacy Export As (or Save for Web): A smooth-looking gradient as expected.

Full resolution/lossless screenshots attached to this post.

[J453]

I notice you're you're not embedding the color profile in the version where you're getting banding. If you check that, does it look right?

[Chain83]

Sorry, forgot to toggle that when taking the screenshot, but no. Embedding the color profile makes no difference; it's just metadata. The color values in the image file does not change, and it doesn't affect the algorithm used to reduce the color palette.

[Chain83]

If it's not clear, I did test with and without the various boxes checked/unchecked, but it makes no difference. New Export As always gets that bad light/dark lines (not what I'd consider normal banding), while legacy export as and save for web always gets a smooth result.

Ps: In Save for Web we have control over what algorithm/settings to use (feature request for Export As!), and I tested a bunch of settings but was unable to get an error of the type seen in the new Export As. 

[J453]

Thanks. I'll have the engineering team take a look.

[Mohit Goyal]

Hi all,  

We're happy to announce the release of Photoshop 23.1. This update includes the fix for this issue. To see the list of all fixed issues, click here. 

To update Photoshop to 23.1, click "Update" in the Creative Cloud desktop app next to Photoshop. More detailed instructions for updating  

Let us know if the update resolves the problem for those affected and share your feedback with us.

Thanks,

Mohit

[defaultkac7l92ac9ov]

Hi guys,

Good news everybody.

This problem is back in the latest version of (23.2.2.).

Downgraded to (23.1.) to get rid of the problem.

In my case dithered egdes were exporting with shart endes.

Just STOP WITH THE UPDATES PLEASE, release one version once a year (but make it good, like you used to).

I am honestly sick and tired of getting an update every week that will break something to be fixed in the next version. I need the suite for work and not for constand mocking about with it, googling for errors and reinstalling the program.

The update everyweek service is much worse than it was when there was a solid version of Adobe Suite 6. Everything seemed to simply work back then.

Ciao,
Alex

[Earth Oliver]

@defaultkac7l92ac9ov @ Unfortunately, Export As has been a complete mess since release. You would think 6 years would be long enough to work out all the bugs and missing/incomplete features, but you'd be wrong.

Good thing Photoshop isn't an application that professionals depend on to keep the lights on!

[BrettN]

@defaultkac7l92ac9ov I just tried it on my end and it is working for me in 23.2.2 (following the instructions in the original post). We haven't made any changes related to this feature area since we fixed this previously. As far as Photoshop's code is concerned when dealing with this scenario, there should be no difference between 23.1 and 23.2.2. Perhaps there is something about your workflow which is different and exposed something which wasn't addressed previously? Or this is something new? Could you provide new steps (if different than above)? Or maybe a sample file? Screen shots? 

[Chain83]

I think you are using the term "dithering" wrong, and what you are trying to say is that semi-transparent pixels become opaque when you choose 8-bit (indexed). This will cause anti-aliased/smooth edges to look jagged/sharp.

This is separate problem from the bug in this thread.

Previously, Export As allowed full 8-bit transparency for 8-bit/indexed PNG files (this is great, and something we missed in Save for Web), but in the most recent versions of Phoyoshop it has stopped working and you now get the same behaviour as with GIF (or PNG-8 in Save for web) where it just sets one of the colors in the color table as transparent (something we rarely want).

[BrettN]

Merged the last reply from @defaultkac7l92ac9ov with the appropriate thread

[Test Screen Name]

I saw a post or two which suggested almost everyone has the wrong idea of the bug that was fixed; it was essentially the opposite bug. 

- PNG allows full colour (often called 24 bit) or indexed colour (by Photoshop called 8 bit)

- full colour can have a greyscale alpha mask, so edges can be any transparency required

- indexed colour does NOT allow a greyscale alpha mask. But it allows transparency values to be applied to the each entry in the colour palette.

- so an "8-bit" (indexed) colour could have 255 levels of transparency, but only for a solid colour (only one colour needed). For a design with, say, 250 colours, there could only be 5 levels of transparency, all of one colour. In other words, it's very limited and the limit in available transparent shades will almost always make a ragged edge (except in the special case of a 1-colour design). 

What I read suggested the bug was NOT that suddenly the export had broken for 8-bit. It suggested a bug was fixed where, if the user asked for 8 bit and transparency, Photoshop would silently switch to 24-bit to give the transparency. 

Here is the test. Does anyone have an image that is

- PNG

- non-rectangular transparency

- multiple colours 

- exported as 8-bit with transparency from an older version from Photoshop

- with good smooth edges 

If anyone has one of these, please share it, and it may be possible to check what Photoshop actually did.

[Chain83]

You're right, i checked the specs and it's alpha values per table entry, not a separate channel. I was mistaken (and with a low enough amount of colors it would look the same). Result is still that you definitely should be able to have semi-transparent pixels in an indexed PNG, and Export As certainly did allow partially transparent pixels originally when choosing 8-bit. And the current version does not.

I don't have any sample files at hand, but if someone installs whatever version of Ps Export As first shipped with, it should be easy to verify how it was encoding the colors/transparency by inspecting the resulting files.

Ps: I also notice that you can't uncheck "Transparency" when choosing 8-bit in Export As. It gets grayed out for no good reason. That's a separate annoying issue. Export As really is still inferior to Save for web for most tasks. Not sure why Adobe just launched it half-done then seemingly stopped developing it beyond a few minor tweaks (like changing the quality slider into a bad drop-down, and then back into a slider). They should give all 3 transparency options and let the user be able to choose. 😕

[mfergie]

Agreed---rolling back to 23.2.1 from 23.2.2 DOES fix the "Smaller File (8-bit)" .png export problem. 

Nothing about my workflow had changed when these gargbage results started "out of the blue" (with 23.2.2)

That being said, I was not having any PSD related issues before 23.2.1 

All hail the roll-back option.

[Chain83]

Could you post a sample image from 23.2.1? Would be interesting to look a bit closer.

(And also, do a new thread for the problem, as this thread is a separate issue).

[jimb86332146]

I concur with the comments here. Since updating to 23.3.0 the 8-bit PNG renders look absolutely HORRIBLE. I was shocked by the renders. Transparency gradients are COMPLETE FAIL!

[andrewb40362617]

Oh god, the horrible aliasing in the latest update was doing my head in. Thanks, Enable Legacy Export As in Preferences seems to have worked.

[phlpsdvd]

I am experiencing the same issue and have updated to the latest PS and its still occurring. The examples provided show the banding with the use of the New Gradient Tool vs the Classic Gradient Tool. The example on top is the Classic Gradient Tool.

[Earth Oliver]

Do yourselves a favor and just avoid using Export As at all costs. Eight years of development and Save for Web is still superior.
As an example of how little Adobe cares about Export As, you STILL CAN'T ADD EXPORT AS TO AN ACTION.
That's right, this tool meant for professionals to help them get their jobs done is not automatable. Nor can you create presets!!!

[Mehebub]

Mehebub alam