Just read a great howto on Perishable Press demonstrating a few ways to optimize PNG without losing image quality. I noticed that OptiPNG hadn’t been updated so I decided to compile it myself. I just got my build environment set up to compile x64 as well, so I decided to give that a shot while I was at it. I noticed a fairly significant decrease in optimization time with the x64 version on my hardware so I figured I’d share the binary. You mileage may vary, depending on your hardware, but here are my unscientific benchmarks based on a small 3DS rendering I did not long ago:

Source: 640×480 pixels, 4×16 bits/pixel, RGB+alpha

OptiPNG 0.6.2.1 x32:
Output IDAT size = 384602 bytes (10771 bytes decrease)
Output file size = 384659 bytes (11347 bytes = 2.87% decrease)

46.9 seconds

OptiPNG 0.6.2.1 x64:
Output IDAT size = 384602 bytes (10771 bytes decrease)
Output file size = 384659 bytes (11347 bytes = 2.87% decrease)

41.6 seconds

For very large and complex files, the time/size savings are marginal, but could be useful when processing a large batch of files. Another intersting feature of OptiPNG is it’s ability to work with 48bit PNG’s… a feature that many commercial tools seem to lack.

Source: 1920×1080 pixels, 4×16 bits/pixel, RGB+alpha

OptiPNG 0.6.2.1 x32:
Output IDAT size = 9816277 bytes (108632 bytes decrease)
Output file size = 9816334 bytes (123164 bytes = 1.24% decrease)

16 minutes, 46 seconds

OptiPNG 0.6.2.1 x64:
Output IDAT size = 9816277 bytes (108632 bytes decrease)
Output file size = 9816334 bytes (123164 bytes = 1.24% decrease)

16 minutes, 20 seconds

Here are the same files optimized by pngcrush for comparison *official win32 binary only as I was unable to get it compiled for either arch.

Small file (29.000 seconds):
Best pngcrush method = 124 (fm 5 zl 9 zs 1) for small.png
(2.65% IDAT reduction)
(2.80% filesize reduction)

CPU time used = 29.000 seconds (decoding 2.962,
encoding 25.868, other 0.170 seconds)

Large file (9.99835 minutes):
Best pngcrush method = 12 (fm 1 zl 2 zs 2) for large.png
(1.09% IDAT reduction)
(1.24% filesize reduction)

CPU time used = 599.901 seconds (decoding 25.295,
encoding 571.670, other 2.936 seconds)

Download OptiPNG 0.6.2.1 x64 Windows Binary

MD5: a7bb617dce7991b0814ed5c1534a0845
SHA1: 3d206584075b2ce555d2d7b3379e480101bccffd

This x64 package is not built or maintained by Cosmin Truţa, the creator of OptiPNG. Please don’t bother him with bug reports or help requests unless you’ve confirmed the problem exists in his official packages as well.