Export to PNG - Result = Huge Files

[GerhardL]

Hello,
I've taken a simple gray gradient from Illustrator with the following problem:

If I export the Gradient as PNG (@ 1x, @ 2x, @ 3x), AD creates huge files (1Mb, 4MB, 9MB), in Illustrator are the sizes (61KB, 176KB, 340KB). Enclosed the file information AI <> AD and the AD document.

What can I do or what am I doing wrong?

:-) Gerhard

Grauverlauf_1680x1050.afdesign

[GerhardL]

Does nobody have an idea or explanation?

[Sean P]

Hi GerhardL,

I've been investigating this issue this afternoon and the reason for the larger file sizes is that we dither vector gradients when exporting to raster formats. This avoids banding from appearing which gives a visually better export than one with banding caused by lack of dithering.

What scenarios is this an issue for you? If its for using as web graphics, would SVG be a better format to use?

[GerhardL]

That is no problem for me, for the web i can export as jpg or as you have written, even more optimal than svg. I just noticed that AD exports the PNG disproportionately large. JPG will also be much smaller in AD than PNG.

[Jowday]

@GerhardL

This is actually because the PNG files Designer exports are rendered in excellent quality. The output is even better than rendered on screen!  No visible banding. I like that. PNG is a lossless format and the intense dithering (thankfully) used by AD means it contains thousands and thousands of pixel patterns that cannot be compressed much with lossless compression algorithms. So PNG files are actually proportionately large.

The PNG export I get from Inkscape shows banding issues and so does files from Illustrator unless I tune the export settings for quality... and then the file sizes matches files from AD. Of course. This is simply how PNG works. JPG files will always be smaller. It is another ballgame. I simply don't understand why anyone can use these files with those levels of banding. 

Photoshop can compress PNG further, though, a 16MB PNG file from AD I opened and saved with maximum compression resulted in a 6MB file. Impressive, but it also took quite some time. 

Your illustrator file.. Think about it. A 5000 x 3000 pixels file saved with lossless compression and the result is only 300KB? It is not possible unless there is a quality trade off. And there is. 

So, PNG is more probably not the right format if you use files this big. Gradients and small file sizes? That's vector territory.

Of course, Serif could add some quality options in the more section in the export dialog for PNG if there is a need out there.