Image formats

SImg supports several image formats.

gzip compressed images

Images may be compressed using gzip. SImg detects that automatically and decompresses this images.


This is a special SImg image format. It supports 8bit fixed point, 16bit fixed point, 32bit floating point and 64bit floating point data. This is the only format which can save all available image extensions.


The `Flexible Image Transport System' is the standard astronomical data format. It can store images as well as other data sets, e.g. spectra. It supports exposure extension partially.

See also:

Digital photo raw images

SImg has compiled-in the dcraw utility. This allows to read these images directly. If the environment variable SImg_cameraWB is not set to 0 the white balance suggested by the camera is applied. Of course, the Bayer extension is supported by these formats.

Convert a Minolta raw image to a 16bit per color pnm image using the “smooth color interpolation” algorithm and doing some bad pixel corrections.

simg bayer -bp 10 -sc -scs 5 pict0123.mrw output.pnm

See also:

PNM family

The PNM family is supported, namely the .pbm, the .pgm and .ppm formats, as well as some extensions, which allow to save 16bit binary data and images with any amount of color channels. Unfortunately there is no standard about 16 bit binary images. By default, SImg stores the data in little-endian byte order. This can be changed by setting the environment variable SImg_PNMLE=0. The output behaviour can also be adjusted using simg convert -16le and simg convert -16be.

The 16 bit mode and the multi color channel modes are only available if the output file ends with .pnm or using simg convert -pnm.

Expects little-endian as input and writes big-endian output:

simg convert -16be input.pnm output.pnm

Expects big-endian input and writes big endian output:

export SImg_PNMLE=0
simg convert input.pnm -pnm output.ppm

See also:


This is a 16bit fixed point image format developed by the camera manufacturer SBIg.


The well known up to 8bit .pcx format.


The well known up to 8bit .bmp format.

common/formats.txt · Last modified: 2011/08/02 09:29 by
Recent changes RSS feed Creative Commons License Powered by PHP Debian Driven by DokuWiki