Rendering image sequence in PNG vs. TGA formats

MARKo · Post by **MARKo** » Wed Sep 22, 2004 5:11 am

I noticed that the TGAs that Moho renders out are not compressed and are quite large. However, PNG files look just as good when you compare frame to frame. They are are also much, much smaller in size.

My question is, does anybody know of any reason not to render out to a PNG sequence as opposed to TGA? The reason I don't go with any of the other available formats is that I want to retain transparent areas so that I may composite my output in a thrid party program, such as After Effects.

Thanks!

spasmodic_cheese · Post by **spasmodic_cheese** » Wed Sep 22, 2004 6:11 am

PNG is lossless so your pretty safe!

Post by **Lost Marble** » Wed Sep 22, 2004 6:16 am

PNG is a lossless format, so the pixels in a PNG image are exactly as Moho created them. This is not true for JPEG. TGA is also lossless, but as you've seen, the compression in PNG gives you smaller files.

Since you wrote what your purpose is in exporting PNGs, I think I should point this out: you can also export a movie file with an alpha channel to use for compositing in After Effects. If you render out a QuickTime movie, choose a codec that offers "Millions of Colors+". The "+" is QuickTime's notation for an alpha channel. The codecs that offer this include Animation, None, PNG, TGA, and TIFF. I think it's much easier to deal with a movie with an alpha channel, rather than a whole bunch of still images.

If you prefer AVI movies, none of the built-in codecs support alpha channels. However, you can download one for free that does. It's called Huffyuv, it's lossless, and it supports alpha:

http://neuron2.net/www.math.berkeley.ed ... ffyuv.html