This post goes over using OptiPNG and AdvanceCOMP to make PNGs smaller. This is especially useful for web designers, as well-compressed PNGs can actually be smaller than GIFs.


Install both programs by running the installer inside the attached file and telling it to install to C:\Program Files\PNG Compression Tools. You will have to modify the batch files if you install to a different directory.

Both of these programs are command-line utilities, meaning that they take text commands only (no point and click interfaces). However, fear not! You can save yourself the trouble of even opening a command-line window by creating shortcuts in the SendTo menu.

To get to the SendTo folder in Windows XP, do the following:

1. Open a run window (WinKey + R).
2. Type sendto and hit enter.

To get to the SendTo folder in Windows Vista, do the following:

1. Open a run window (WinKey + R).
2. Type (or paste) %appdata%\Microsoft\Windows\SendTo and hit enter.

Once in the SendTo folder, do the following:

1. Right-click an empty area, an go to New > Shortcut. The New Shortcut Wizard will appear.
2. In the box where you would type the location of the item, enter the location of "Re-Compress PNGS.bat" ("C:\Program Files\PNG Compression Tools\Scripts\Re-Compress PNGs.bat" if you have it installed in your Program Files directory).
3. Enter a name for the new shortcut, I recommend Re-Compress PNGs.
4. Create a new shortcut for "Re-Compress PNGs in Folder.bat", with the location: "C:\Program Files\PNG Compression Tools\Scripts\Re-Compress PNGs in Folder.bat". Name it Re-Compress PNGs in Folder.

To re-compress your PNG file:

1. Right-click the PNG file, go to Send To > Re-Compress PNGs. A command window will appear and you will see the output of OptiPNG and then AdvanceCOMP as they re-compresse each file. OptiPNG/AdvanceCOMP will not overwrite your PNG file if the output file size would be larger.
   
   Further Information
   
   • It is necessary to use OptiPNG first, because OptiPNG performs a more advanced re-compression of the PNG file. It applies delta filters, removes unnecessary data chunks, and reduces the bit depth if possible (without reducing quality). AdvanceCOMP uses the 7-zip DEFLATE algorithm (which is more effective than the standard one) to make the file smaller.
   • OptiPNG can also be used to covert gif, bmp, pnm, and certain tiff images to png.
   • OptiPNG on Wikipedia.
   • AdvanceCOMP on Wikipedia.
   
   Here is an example of the kind of compression you get using this method. The original file was 765KB.
   
   • Compressed only with OptiPNG, it is 681KB. (10.9% savings)
   • Compressed only width AdvanceCOMP, it is 739KB. (3.3% savings)
   • Compressed with AdvanceCOMP then OptiPNG, it is 681KB. (10.9% savings)
   • Compressed with OptiPNG then AdvanceCOMP, it is 679KB. (11.2% savings)

Bigger savings are had when the bit depth can be reduced (ex: grayscale or images with <= 256 colors).

Last Updated: July 24, 2008

Although very interesting and useful(for others), I doubt I'll use it. But it is still awesome nonetheless. Good work

Jun 28, 2008

• Updated to include OptiPNG 0.6.
• Now includes scripts to make PNG re-compression required only one SendTo action.
• The scripts have the capability of compressing multiple PNGs at once.

I actually have ended up using it and it does save a significant amount of space when done in bulk!

July 24, 2008

• Updated OptiPNG to version .0.6.1. - Changes

Can't thank you enough for writing this post. Could hardly believe it took me half to find how to set these up because there are no instructions on sourceforge. This is the simplest and clearest procedure I have found.

I'm glad you find these useful!


Please be aware I haven't updated the programs distributed with these scripts in ages. I highly recommend that you grab the latest OptiPNG and AdvanceCOMP and replace the versions I distribute with the updated versions.