PngOptimizer v2.3

Checker on 30 May 2013
  • 284KB (uncompressed)
  • Suggested by Replika

PngOptimizer is an easy-to-use program to compress common graphics formats to PNG format with no visible quality difference. Files can be added one at a time or in batch to the program icon or window. even from the clipboard (press CTRL+V while the application is in focus). Graphics formats supported include BMP, GIF, TGA, as well as further compressesing PNG files by removing unnecessary data without affecting quality. Animated GIF and PNG files (APNG) are also supported.

Size decrease for PNG files are on average between 5-10%, but GIF and BMP conversions can be as much as 40% to 90% respectively.

System Requirements: WinXP / Vista / Win7
Writes settings to: Application folder
Stealth: ? Yes
Unicode support: Yes
License: GPL
How to extract:
  1. Download the ZIP package and extract to a folder of your choice
  2. In the same folder, create a text file called PngOptimizer.ini where settings will be written and with a few random characters (e.g. asdf)
  3. Launch PngOptimizer.exe

Optionally, to save images from the clipboard to the PngOptimizer application folder, right-click on the window and select Custom for the target directory and enter a period (.) in the box below.
What's new?
  • new: multithreaded optimization for faster processing on multicore CPUs
  • new: better optimization in some cases of greyscale images
  • misc: updated ZLib 1.2.5 to 1.2.7 (compression library)

9 comments on PngOptimizer  The Portable Freeware Collection Latest Entries Feed

Jan 2009-02-08 09:37

It takes forever to start this app. On windows XP.

Teo 2009-02-20 00:41

Agree, 65% processor time and start after 2 minutes on P4/2GHz? No way, this PngOptimizer must be optimized.

Jon Wright 2009-02-20 12:43

Just downloaded 1.8 - same problem. Nothing's appeared and processor is using 100% on one core. Three minutes now so it'll have to be killed.

tun 2009-02-21 09:10

If we don't create ini file, it is working fine.

tun 2009-02-21 09:15

Create the 'PngOptimizer.ini' with the following content and save in 'UTF-8' format

================ start ===============
; PngOptimizer configuration file
; This file is encoded in UTF-8

BackupOldPngFiles = 1
KeepInterlacing = 0
KeepBackgroundColor = 0
AvoidGreyWithSimpleTransparency = 1

UseDefaultDir = 1
CustomDir =
MaximizeCompression = 1
AskForFileName = 0

X = 345
Y = 215
Width = 521
Height = 300
============== end =====================

Webfork 2009-11-11 20:06

Great program. Thanks tun for the ini config trick.

Paul 2011-05-10 01:01

.. with just a few random characters like the asdf example in 'PngOptimizer.ini' .. the new update works great on Win98 (or the whole ini template)


webfork 2011-11-03 17:35

This program is great for general PNG compression, but for web graphics that will see many downloads over time, I use RIOT (


webfork 2013-05-31 23:08

Note about the 2.3 update: definitely takes full advantage of multi-processor systems. I tested it on Win7x64 with an i7 quad core and it got very close to 90% (few programs can do that). Definitely a big speed bonus over time there and good to see those kind of optimizations in freeware.


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