Doing some design for 3D and developers need PNGs with RGBA8 for transparency. I am not even sure if this is possible with png. When I look at channels I see no alpha channel but there is alpha on the png, which is very confusing.

My flow is usually through generator, so I name layers fileName.png32 so it does full alpha but they turn out wrong and I have to open them and resave and that fixes it somehow (though I still cannot see alpha channel).

edit: more details. Here are the actual error I get from the program trying to import the PNG.

MakeImageCompatible: Converting Image 'item url here' from TEXFMT_BGR8 to TEXFMT_BGRA8

so its saying somehow it cannot read the alpha channel from what I gather.

  • The layer transparency within Photoshop is the alpha, there's no separate specific channel for that alpha. – Scott May 7 '14 at 23:34
  • so guess the question remains, does png even support RGBA8, or would I have to use something else like tiff or tga? – wutronic May 7 '14 at 23:58
  • Yes PNG32 = RGBA. Saving a file which contains layer transparency in Photoshop as PNG24 results in a PNG32 image. It is slightly convoluted since there's no specific reference to PNG32 within Photoshop. – Scott May 8 '14 at 0:03
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    I really do not understand... "naming layer filename.png32 forcing it to go 32" Names have never "forced" Photoshop to do anything in terms of formats. – Scott May 16 '14 at 0:57
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    Thanks for the info! Both files are perfectly fine PNGs (according to pngfix-32; no errors or warnings whatsoever). Closer examination shows that their IDATs (duh ;}) and some pixel values (may be caused by color management) differ. Besides that, the first has additional 5 chunks defined, that the second file is missing: bKGD, cHRM, gAMA and 2 text. The first of them declares the background color, so my guess is it could be misinterpreted by some half-baked PNG decoder. More could probably be said if we know some more details about the target app. – thebodzio May 16 '14 at 14:24

Is it possible to export RGBA PNG from Photoshop? Very much so!

As Scott said, there's no separate “alpha” channel visible in “Channels” panel, but the alpha channel is there anyway (just not “shown” in the panel), as long as the image doesn't have the “Background” layer. Anyway this alpha channel is used when PNG files are saved. If you need some more control over your PNG files saved by Photoshop, I recommend you to use the “Save for Web”.

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