Formats Supported

Format Read Write Since version Notes
PNG Y Y 0.1  
PNG (16 bits) Y Y 0.4  
TIFF Y Y 0.1  
JPEG Y Y 0.1  
WEBP Y N 0.2  
BMP Y N 0.2.5 Only uncompressed bitmaps are supported.
STK Y N 0.2  
LSM Y N 0.2.2  
XCF Y N 0.2.2 Only if xcf2png utility is found in the path.

Options

Some of the formats allow you to specify options when saving. These are inevitably format specific.

PNG

png:compression_level
Compression level to use, from 0 (no compression) to 9. Setting it to 0 is discouraged.

JPEG

jpeg:quality
An integer 1-100 determining the quality used by JPEG backend (default is libjpeg default: 75).

TIFF

tiff:compress
Whether to use compression when saving TIFF (default: True)
tiff:horizontal-predictor
Whether to use horizontal prediction in TIFF. This defaults to True for 16 bit images, and to False for 8 bit images. This is because compressing 16 bit images without horizontal prediction is often counter-productive (see http://www.asmail.be/msg0055176395.html)