FITSPNG(1)                       User Commands                      FITSPNG(1)

       fitspng - FITS to PNG converter.

       fitspng [options] file(s)

       Fitspng is an utility intended to convert of images in astronomical
       FITS format to computer graphics PNG format.

       The primary goal of fitspng is to transform of the high dynamic images
       to a limited numerical range of PNG format. The transformation uses
       global tone mapping by a set of tone functions with machine estimated
       or user provided scaling parameters.

       The detailed description can be found at homepage:

       -f [linear|asinh|log|gamma|normal|sqrt|sqr|logistic|atan]
              Scale output intensities by specified profile: linearly, asinh,
              log, gamma (as in sRGB), normal (Gauss cumulative distribution
              function [5]), square root, square, logistic (emulating
              classical photography sensitivity [6]), atan and ratio (x/1+x).

       -f0 f  Specifies scale of output profile: f*Func(i).

       -fz z  Specifies zero (black level) of output profile: Func(i) + z.

       -fr u,v
              Output intensities, in case of colour depth 8 bites, are scaled
              according this formula: (output intensities) = Func((input
              intensities - (med - u*mad))/(mad/v)) where med is median of
              every 10 pixel in the image, mad is mean of positive deviations
              from the median of every 10 pixel (same frequency). If the pixel
              is out of level range from 0 to 255, than value is replaced by 0
              and 255 respectively.  The default is u = 3, v = 1/3.

       -fl t,s
              Output intensities, in case of colour depth 8 bites, are scaled
              according this formula: (output intensities) = Func((input
              intensities - t)/s).  The setup completely disable internal
              parameter estimation.

       -fs x  The colour saturation is multiplied by the given ratio (for
              colour FITS only).

       -fw x,y
              Set coordinates of white point.

       -fn st,ss
              When used, switch-on mode which emulates humans night vision. It
              is useful only for colour FITS.

       -cs sRGB or AdobeRGB
              Select the colour-space of output image.

       -s s   Shrink image: scale down the size of image by the specified
              factor s as a (non-zero) positive integer number. If the s
              factor is greater of one, any output pixel is constructed as
              arithmetic mean of s*s input pixels.

       -o     Specify an output file name, valid only if a single file is

              If this switch is omitted, the output filename is determined by
              modification of input filenames: suffixes, like *.fits, are
              replaced by *.png, and the directory path is removed. The
              approach leaves original data untouched, results are stored in
              current working directory.

       -B [8|16]
              8 bites per pixel of colour (gray) depth of output. This is
              default.  16 bites per pixel of colour (gray) depth of output.
              There is frequently problem with additional rendering. Most of
              utilities doesn't work with this colour depth correctly. On the
              other side, 16 bit per pixel images has saved photometric
              content more precisely.

       -v     Print additional info during processing.

       --help Show summary of options.

              Display software version.

       Convert an image from FITS to PNG:
           $ fitspng -o gray.png gray.fits

       Emulate human's night vision:
           $ fitspng -fn 100,10 -o scotopic.png  colour.fits

       Emulate classical photography sensitivity function (density curve):
           $ fitspng -f logistic -o photo.png colour.fits

       Create semi-gray image:
           $ fitspng -fs 0.2 -o reduced.png colour.fits

       Select the specified band from colour FITS (with help of FITS file name
           $ fitspng -o green.png "colour.fits[1]"

       Create thumbnails:
           $ fitspng -s 10 *.fits

       Filip Hroch <>





Fitspng                          January 2019                       FITSPNG(1)