JPG-Compression and File Size
The following table illustrates the file sizes for the images used before, resolution of the full pictures is 10 megapixels.
There is no common standard how the level of JPG compression is quantified. Photoshop uses a scale from 0 to 12, other programs may have a scale up to 100 and cameras have usually just two or three levels with symbols or names, no figures at all.
Accordingly you may need to use different values in your favorite software to produce similar results; mine are based on a range from 20 to 100.
|image quality||file size||comment||file size of sample images in MB|
|for comparison: Bitmap format (.bmp)||29,4 MB|
|best JPG quality||
|see section „best possible JPG quality“
JPG quality: 100
|11,9 / 17,1 MB|
|good JPG quality||
|see section „color shift“
JPG quality: 80
|1,6 / 2,5 MB|
|medium JPG quality||
|see section „JPG artifacts“
JPG quality: 50
|0,9 / 1,5 MB|
|lowest JPG quality||
|see section „square shaped blocks and loss of details“
JPG quality: 20
|0,5 / 0,8 MB|
For comparison: When using the PNG format which is very popular for lossless compression there would be files of about 15 and almost 20 MB left.