JPEGmini promises to reduce the file size of a JPEG image up to 5x, while keeping the source file's quality. I made a few tests with different JPEG compression levels to test if this is true. The source test file is a 16 Bit-TIFF in 3264x4928 px resolution with a file size of 96.5 MB.
I exported the test file from Adobe Lightroom 5.7 as a JPEG file with quality levels from 0 to 100:
I compressed the ten test JPEGs with JPEGmini:
Here is the result:
|Source quality||Source file size||Compressed file size||Reduced by||Download test images|
|100||10.2 MB||2.5 MB||75%||ZIP file (12.7 MB)|
|90||6.6 MB||2.4 MB||63%||ZIP file (9 MB)|
|80||4.5 MB||2.4 MB||46%||ZIP file (6.9 MB)|
|70||3.2 MB||2.1 MB||34%||ZIP file (5.3MB)|
|60||1.8 MB||1.8 MB||0%|
|50||1.9 MB||1.7 MB||10%||ZIP file (3.6 MB)|
|40||1.5 MB||1.5 MB||0%|
|30||1 MB||1 MB||0%|
|20||987 KB||987 KB||0%|
|10||735.8 KB||735.8 KB||0%|
|0||635.6 KB||635.6 KB||0%|
Here is a comparison chart with a detail of the image in 1:1 resolution:
The test JPEG with quality level 100 was compressed by factor 4.1x in JPEGmini. Maybe it's possible to get even better results with different images. The quality is amazing, there is nearly no difference between the original file and the compressed file.
You can download JPEGmini Lite for free in the Mac App Store. The lite version is limited to 20 JPEGs per day. The full version costs 19,99 €.
You can also try JPEGmini online by uploading a picture to their website: http://www.jpegmini.com