How is paint.net able to reduce size of Yahoo smushed image

[MonsterMMORPG]

Hello. When i open file with paint.net and click save sometimes it make it larger and sometimes it make it smaller. When the bith depth is selected as auto are there any chance that paint.net will loose quality ? I check that generally bith depth is not changing it is 32 bit but it is able to reduce size of image which have been yahoo smushed or pgnoutwin processed. How is this possible ?

Are there any plugin which will batch read images and save them if the new size is smaller without quality loss ?

[Rick Brewster]

When "Auto-detect" is chosen, Paint.NET will never choose a bit-depth that will result in a loss of fidelity/quality. File size differences are just differences in the compressor's aggressiveness. Programs like pngout or optipng take a very long time to save an image, which usually isn't acceptable. Those programs should be used as a "final pass" in a content publication system.

[MonsterMMORPG]

When "Auto-detect" is chosen, Paint.NET will never choose a bit-depth that will result in a loss of fidelity/quality. File size differences are just differences in the compressor's aggressiveness. Programs like pngout or optipng take a very long time to save an image, which usually isn't acceptable. Those programs should be used as a "final pass" in a content publication system.

my question is how come paint net able to reduce size of image which was processed by pngoutWin best compression without quality loss ? i am attaching sample image

this image is compressed by pngoutWin yet paintNet is able to reduce size at automatic

Edited September 11, 2011 by MonsterMMORPG

[MonsterMMORPG]

i appreciate any answer thank you.

[Rick Brewster]

I don't see that happening. The png you link to is 7.42KB. Paint.NET, using Auto-Detect, results in a 7.6KB size and retains the 32-bit color depth. It only reduces the file size if you specifically choose 8-bit, at which point it's losing fidelity.