Using varied compression rates for jpg --


BITMAP

image size:
400 x 561 pixels

file size:
657 KB
bitmap (converted from PSD in GIMP)
JPEG

400 x561
(same as above)

compression:
1 %

file size: 144 KB
1 %
compression:
5 %

file size: 77 KB

5 %
compression:
10 %

file size: 53 KB
10 %
compression:
40 %

file size: 24 KB
40 %
compression:
70 %

file size: 16 KB
70 %

Note: Right-click an image, then left-click Properties to see image size, file size, etc.