.PNG Interlaced? or NONE

[Lee_Hitsugaya]

What comes out with better quality. Speak your mind and help me decide.

[PyTom]

I would suggest no, unless you plan to use the images on the web or something. Ren'Py decodes the image until it's done, so the interlacing doesn't accomplish much... but it probably makes the image a bit larger, so there's a small downside to using interlacing.

BTW, I think it's inappropriate to conduct a poll on a technical issue like this. Polls work when you want to gauge the sense of the community. For a technical thing, it's best to listen to peoples advice, and make up your own mind.

If ten people come here and agree with me, and one person comes here and says that I'm wrong (say, because interlaced PNG is smaller... I don't know, I haven't actually done the experiments), and that person is factually right... well, listen to the one person who got it right, rather than the 11 that got it wrong.

[Jake]

What comes out with better quality. Speak your mind and help me decide.

Neither.

Or rather, both. Interlacing is nothing to do with the image quality at all. PNG is a lossless format, so you'll get the same image regardless of what you choose here. The only thing that will affect your quality is what colour depth you choose - the higher the number of bits per pixel, the better (although computer monitors peak at 24/32bpp and the human eye can't tell the difference between all of those anyway).

What interlacing does is determine the order that the pixels are saved in the file. To give a simplified example:
Normally (non-interlaced) the pixels are just written into the file starting at the bottom left, proceeding along to the right until the end of the line is reached, then starting at the left one line up, proceeding to the right... and so on.
An interlaced image might store every fourth line in that manner, then go back and fill in every second line, then go back and fill in all the lines in-between.

The advantage to this being that if you only have the first quarter of the file, you can still reconstruct a reasonable approximation of the image because you have every fourth line and you can guess at what goes on the ones in between. It'll be low-res and blurry, but it'll be better than nothing. If you have only a quarter of the normal image, you have the bottom quarter of the file, which isn't normally so useful. This is most commonly used in web browsers to show in-progress versions of the file as the image is being downloaded; the browser will show the low-res blurry version, then fill in the details as it recieves them, making the image more and more high-res until it's all downloaded.

The disadvantage to interlacing is that the approach taken with PNG messes with the compression scheme, so interlaced PNG files usually aren't so small as the same image non-interlaced. So for purposes where the interlacing is useless anyway - for example game-making, where the file is loaded very quickly from the local HDD - it's probably best to save your files non-interlaced.

[Twar3Draconis]

Pretty much what everyone else said. For web-based items I use interlaced. For offline items I don't.