This topic has come up recently, as well as a variety of times before.

Png images (without a background layer) used for decals seem to render darker than jpgs, or tgas. So to confirm for myself that there is a difference in using png file type, versus tga and jpg, I ran a test. I do not know if the difference in results are due to A:M, or the way photoshop handles pngs.

I took the original png image which had NO background, added a white background (layer), saved (in photoshop 6.0) as a new png. Then saved a copy in jpg format, and tga format. I did not do any adjustment to the image itself.

Very interesting. I've always used PNGs for decals but kind of got used to just adjusting them via photoshop. I think I'll be switching image formats in the future

interesting that the png with a white background is so different from the original. To me the jpg produces the best results

TGA is an uncompressed format, whereas JPG is compressed.

In this case since the image is so large (high resolution) and I saved the JPG with highest accuracy (least compression) available, there isn't much noticeable difference between JPG and TGA file types. I suspect your eyes are playing tricks, due to the perspective in the chor.

Best to use TGA if you don't want to worry about compression artifacts (blocky looking, loss of detail, change in color range).

Thanks, Nancy.

I recall reading of some sort of mistake (or was it a feature?) in the development of the PNG format the messes up the way it handles gamma.

It had something to do with supposedly gamma-aware browsers that would somehow compensate for images that came from sources with different gamma standards... or something like that.

All i know is I never use PNG except to post the occasional screen capture.

PNG alpha channels also don't show up as alpha channels in my old Photoshop so that's another reason I avoid them.

I have old photoshop as well (ver 6). This original png had no background layer, but had transparency in the one layer.

I will render from A:M to PNG format (no alpha), and it does not seem to be a problem when I bring those png sequences into Adobe AfterEffects (CS4 - a gift from a non-profit org!).

I also use png to post images to forum. PNG is nice in that it is supposedly a lossless format, with a nice small file size compared to TGA (large file sizes).

If you create/modify PNG images in Photoshop, you must then change the Gamma of the PNG to "0" in a program like TweakPNG.
http://entropymine.com/jason/tweakpng/

Remembering an explanation from Yves, I believe he said A:M correctly reads the gamma value from the PNG file, but Adobe products write a strangely high gamma value in any png image they create or modify.

That is correct.