JPEG optimization tools benchmark
Intro
I have a web project that hosts more than 15.000 images of various sizes from 300kb up to 10MB.
In total these images take about 8GB of space. These images are served from a small VPS with 365MB of RAM and optimized LAMP stack with Nginx as reverse proxy.
Since I am a performance freak, I want to speed up the image serving as much as possible.
But before tweaking any server settings I have to optimize the images themselves.
For this I started looking for linux JPEG optimization tools and found a few, no idea which one is the best so I decided to run a few benchmarks and share the results with the rest of you.
List of tools
jpegrescan - A lossless jpeg optimization script written in Perl. Created in 2008 and hosted for a long time on a pastebin page it doesn't inspire a lot of confidence, but why not.
jpegtran - A popular tool for lossless jpeg optimization.
JPGCrush - Found only as a comment on hacker news without any documentation or info. Lets do this!
jpegoptim - Maybe the most popular tool for lossless and lossy image optimization
imgopt - A rather simple bash script that uses multiple tools at the same time to achieve maximum optimization.
Benchmarks
For the benchmark I am going to use the following:
4 random images from /r/serverporn.
My own image collection of 872808kb.
First I am going to test the 4 random images
| Name | Type | Parameters | Total size before (KB) | Total size after (KB) | Difference |
|---|---|---|---|---|---|
| jpegrescan | lossless | none | 3772 | 3556 | -5.726% |
| jpegtran | lossless | -copy none -optimize | 3772 | 3724 | -1.273% |
| jpegtran | lossless | -copy none -optimize -progressive | 3772 | 3560 | -5.62% |
| JPGCrush | lossless | none | 3772 | 3772 | 0% * |
| jpegoptim | lossless | --strip-all | 3772 | 3724 | -1.273% |
| jpegoptim | lossly | --strip-all --max=90 | 3772 | 3236 | -14.21% |
| imgopt | lossless | none | 3772 | 3724 | -1.273% |
| *Not sure where is the problem. It run just fine with no results. I will be excluding it from the next benchmark. |
And now some heavy testing. I have a directory with 2400 images and a total size of 853MB.
Lets see how the tools are doing on a larger scale.
| Name | Type | Parameters | Total size before (KB) | Total size after (KB) | Difference |
|---|---|---|---|---|---|
| jpegrescan | lossless | none | 872808 | 756976 | -13.271% |
| jpegtran | lossless | -copy none -optimize | 872808 | 797764 | -8.598 |
| jpegtran | lossless | -copy none -optimize -progressive | 872808 | 770764 | -11.691% |
| jpegoptim | lossless | --strip-all | 872808 | 819896 | -6.062% |
| jpegoptim | lossy | --strip-all --max=90 | 872808 | 606260 | -30.539% |
| imgopt | lossless | none | 872808 | 832072 | -4.667% |
Summary
I didn't expect this, jpegrescan has the best lossless compression compared to all other tools including the most popular ones. Of course it took about 4-5 times longer to finish, but still, who knew.
And of course the winner is jpegoptim with lossy compression and quality of 90.
I think this the best option, since the users can not tell the difference between 100 and a 90 quality but the size reduction is significant.