Pack JPEG is a new type of image file format that gives around 20% better compression than the traditional JPEG file format. This new format was first presented in the year 2007 at the Picture Coding Symposium. In the past few years this new Pack JPEG (or PJP in short) image file format has become much more efficient and can now compress the JPG pictures with much higher compression without losing any quality. The wxPackJPG program can be used to compress your JPG image collection into the new PJG file format giving you lossless 20% more compression so that your images take lesser space on the storage media and take lesser time when transferred online.
The wxPackJPG program is pretty straightforward and can be thought of as a PJG compression and decompression tool. You can add a number of JPG files in the The wxPackJPG program, choose a destination folder and click on the Compress! button. The files are compressed and saved into the new PJG file format in the destination folder. The compressed size is shown alongside the original file size for each of the files, so that you can see how much space you have gained through the compression.
The decompression works in a similar way. This time, you have to select the PJG files from your hard disk and choose a destination folder for the JPG files and then click on the Decompress! button. The files are decompressed right away and you can view them using any image viewer.
The only problem with the PJG file types is that no mainstream image viewer supports them as of now. The XNView image viewer does support PJG file types, but somehow it fails to load the PJG files generated by the wxPackJPG program. In any case, you can see a preview of the PJG images in the wxPackJPG itself.
Conclusion: The wxPackJPG can compress your JPG image collection into the much smaller PJG file types. The compression is lossless and retains the full original JPG image quality.
You can download the wxPackJPG program from http://wxpackjpg.sourceforge.net/.