Batch Processing Bitmaps to New Formats and New Settings

January 25, 2014

Batch Process BitmapsI recently received thousands of JPG files. When I looked at the file sizes, they just seemed way too large for what they contained. Just to make sure I wasn’t crazy, I opened up one file and resaved it at a very high quality. The new file size was less than 10% of the original file. I don’t know what caused the originals to be so large, I just know that they are too large and I can make them much smaller.

How would you like to open thousands of bitmaps and immediately resave them? To me it sounds like the perfect cure for insomnia! This was the perfect project for batch processing. I first attempted to do the batch processing using the tool included with Corel PHOTO-PAINT. The resulting files weren’t as small as what I desired and not all the changes I wanted were made. Even more frustrating was that I got an “Out of Memory” error when I tried to open a folder containing around 300 files. Note that this was not a crash, it just simply wouldn’t let me select all the files. Even weirder was that the files weren’t all that large in terms of the number of pixels.

That led me to one of my favoritest utilities ever. OK, maybe I just invented a word. It is worth it for Irfanview. Remember, it is completely free so everyone should have a copy. I won’t revisit all it can do as I’ve written about it many times in the past. I wanted to batch process files and Irfanview has just such a feature. I pointed it at the folder of bloated JPGs and selected the settings I wanted for the new versions of the file. It easily converted all of the files and did it in less than a couple of minutes. The resulting files were around 93% smaller than the originals and I can’t find any loss in quality.

Using Irfanview to convert all of these files will save me many hours of tedious work. Unfortunately I probably won’t get as much sleep since I’ve lost that cure for insomnia.

Post Discussion


  1. sean72

    Sometimes embedding the color profile outweighs the size of smaller jpg images. Otherwise, I don’t know what would bloat the files, that would be an interesting file analysis project.

  2. Foster D. Coburn III

    Sean, it seems there are number of extra things in the files causing the bloat. As a rough example, files are going from 600KB to less than 30KB without changing pixel size or compression. The original are CMYK which makes no sense for black/white JPG files and they do seem to have extra junk embedded (color profiles, EXIF data, etc). It is simple enough to batch fix them as 500 files can be repaired in less than a minute.


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Foster D. Coburn III built his first Web site in 1995 and he has been working exclusively in WordPress since 2013. He has used the Divi theme exclusively since 2015. Earlier in his career he was the author of 13 best-selling books on CorelDRAW and has been a contributor to numerous technology and graphics-related magazines. Foster has taken many projects, including this Web site, from the early design stage through to a finished piece. He has been a featured speaker at many graphics conferences.

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