Using PNGExtra

PNGExtra Main Screen

What to Process The left side of the window shows the drives on the system and the current folder plus a selection of which file types to process. Use the “Browse” button or double-click on the Drives or Folders to navigate to the folder to process.

Matching Files The middle of the window shows the list of files in the chosen folder that match the file specification. The default specification is *.png, which is the normal file specification for PNG files. Click on any individual file for details of that file (date, size). Double-click on any individual file to process just that one file.

Processing The right side of the window shows the “Start Processing” button, totals of all files processed and totals of those files that were actually optimized, plus various processing and log file options.

Overview of Usage

The idea is to more or less work from left to right. Choose the drive you want to process, choose the folder, choose the file types (eg. *.png, meaning all files that end in .png), then set any options and either click on the “Start Processing” button (to process all files) or double-click on any individual filename (to process just that one file).

PNGExtra Options

Processing Options

• Analyse Only / Don't Modify: Check this option to allow a “test run”, which will show what savings can be expected without actually modifying the files. As mentioned above, the Log File is useful for analysing the results.

Un-check this option for normal processing.

• Process Sub-Folders Also: Check this option to also process any lower-level folders that are found within the chosen folder. For example, processing the “C:\My Documents” folder will also process the lower level “C:\My Documents\My Images” sub-folder, plus anything else further below. A whole drive can be processed in one pass using this option.

Un-check this option to only process the current folder.

• Pause on Errors: Check this option and when PNGExtra encounters any errors, it will pop up a dialog box showing the error, allowing you to continue or to cancel further processing.

Un-check this option for uninterrupted processing.

• Backup Original Files: Check this option and when PNGExtra does modify a file, it will create a backup of the original file. This will have the same filename but with a different file extension. For example, “123.png” becomes “123.old”.

Un-check this option and no backups will be made.

Backups are valuable for several reasons. Firstly, to compare the optimized file with the original file to verify that the image is unchanged. Secondly, in the unlikely event that there is an error with the optimized file, the original file is still available. Thirdly, to keep the original, unaltered file for archival purposes, as it may contain data (such as a meaningful comment, Exif digital camera info, etc.) that could prove useful in future for historical or legal reasons.

• Keep 8-bit Transparency: Check this option and any 8-bit PNG files – which have transparency values stored in a separate palette – will keep their transparency.

Un-check this option and 8-bit PNG files will have their transparency palette discarded as “extras” and thus will lose their transparency and become opaque.

Log File Options

• Log All Files Processed: Check this option to create a log entry for each file processed, even if the file was not modified or if there were any errors processing that file. If there was already an existing log file, add the entries to it, otherwise start a new log file.

• Log Files With Extras Only: Check this option to only create a log entry for those files that were found to contain extras and that were successfully optimized without errors.

• Don't Write to Log File: Check this option to not create a log file (although if one already exists, don't delete it).

Other Options

• Remember All Options: Check this option to remember all of the above options for the next time PNGExtra is run. This creates a tiny entry in the Windows registry (ie. there is no major change to the registry, so don't panic!)

Un-check this option and next time PNGExtra is run, all options will have reverted to their default settings.

For those interested, the settings are saved in the following registry key:

HKEY_LOCAL_MACHINE/Software/Ian Fieggen/PNGExtra1

Note that PNGExtra doesn't store anything critical in the registry, only these options. Anyone who is comfortable with editing the registry can safely delete this registry key to similarly revert to defaults.

PNGExtra Website

The “Help” menu also contains a shortcut to go to the PNGExtra website. Note that this does NOT communicate anything, private or otherwise; it simply points your browser to the website address.

Typical PNGExtra Usage

Optimizing Existing PNG Files

Typically, users have a “library” of all of the PNG files for their website sitting somewhere on a production computer. It's a simple matter to navigate to that folder using PNGExtra and process all of the PNG files therein. The optimized PNG files can then be re-uploaded to the website.

Optimizing Newly Created PNG Files

When working on additions to a website, it's often a good idea to temporarily place any newly created PNG files into a separate folder (eg. “C:\NewPics\”). This simplifies the task of optimization because PNGExtra can very quickly process that one folder, after which the optimized PNG files can be uploaded to the website as well as copied back to the image library.

Re-Optimizing PNG Files

Unlike most other PNG optimization apps, PNGExtra can be run over the same PNG files any number of times. This is because PNGExtra does not modify the image data in any way and thus will never reduce their quality. If PNGExtra finds no “extras”, those files will not be changed.

It's a good exercise to occasionally run PNGExtra over the whole of an image library to double-check that no files containing “extras” have made their way into the library (eg. through simply forgetting to optimize, or restoring an old version of a file). After re-processing the library, a quick check of the totals will show if any files were optimized. The log file will then be invaluable for determining those files that need to be re-uploaded.