P: Split channels on large CMYK files gives glitches when converted to bitmap or saved as tiff

[kayr23628964]

This has happened to me on CS6 and now with CC on OSX running El Capitan. When I split channels on a large CMYK file the resulting files look fine, but when I convert them to bitmap or save them as a grayscale .tiff or .psd I wind up with glitched files. This does not happen if I cut and paste the channel into a new grayscale file, so I think it is a bug in the split channels code. Original CMYK file was 7393x5700 pixels

BITMAPPED WITH A HALFTONE SCREEN




SAVED AND REOPENED AS A GRAYSCALE TIFF


ORIGINAL IMAGE AFTER SPLITTING CHANNELS ( BLACK CHANNEL )

[J453]

Does this happen consistently (100% of the time) with all files or this particular file?

[J453]

I wasn't able to reproduce this creating my own CMYK file, splitting the channels and saving a tiff of each file using the default settings in the Tiff options dialog,

[kayr23628964]

It only happens if the CMYK file is not flattened and split channels creates a transparency channel. I can create a new file the same size and there is no problem. Double click the background layer to make it Layer0, and the glitch manifests. I flattened the original file and now there is no glitch.

[J453]

OK. The sounds like it might be the secret sauce. Let me try that.

[kayr23628964]

I can also send you the file I used if you can't replicate the bug, but I was able to get it to happen with a file I created in photoshop.

[J453]

That was the secret. I have a repro case now. Engineering will look into it. Thanks for your help!

[kayr23628964]

That's great! Also easy to work around now that I know.

[FeedbackCommunityMember]

Ah, yeah, that is something that wasn't mentioned in previous reports.
And that tells me where the error might be...

[FeedbackCommunityMember]

Yep, those steps (transparency, large image) were both important.
I've implemented a fix for this in the next major release of Photoshop.

[J453]

Chris fixed this issue fixed fixed this issue in the CC 2015.5 upgrade released today: https://blogs.adobe.com/photoshop/2016/06/adobe-releases-major-photoshop-cc-update-today-and-announc...