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falsecolor - make a false color RADIANCE picture


falsecolor [ -i input ][ -p picture ][ -cb | -cl ][ -e ][ -s scale ][ -l label ][ -n ndivs ][ -log decades ][ -m mult ][ -r redv ][ -g grnv ][ -b bluv ]


Falsecolor produces a false color picture for lighting analysis. Input is a rendered Radiance picture.

By default, luminance is displayed on a linear scale from 0 to 1000 nits, where dark areas are blue and brighter areas move through the spectrum to red. A different scale can be given with the -s option. The default multiplier is 179, which converts from radiance or irradiance to luminance or illuminance, respectively. A different multiplier can be given with -m to get daylight factors or whatever. For a logarithmic rather than a linear mapping, the -log option can be used, where decades is the number of decades below the maximum scale desired.

A legend is produced for the new image with a label given by the -l option. The default label is "Nits", which is appropriate for standard Radiance images. If the -i option of rpict(1) was used to produce the image, then the appropriate label would be "Lux".

If contour lines are desired rather than just false color, the -cl option can be used. These lines can be placed over another Radiance picture using the -p option. If the input picture is given with -ip instead of -i, then it will be used both as the source of values and as the picture to overlay with contours. The -cb option produces contour bands instead of lines, where the thickness of the bands is related to the rate of change in the image. The -n option can be used to change the number of contours (and corresponding legend entries) from the default value of 8.

The -e option causes extrema points to be printed on the brightest and darkest pixels of the input picture.

The remaining options, -r, -g, and -b are for changing the mapping of values to colors. These are expressions of the variable v, where v varies from 0 to 1. These options are not recommended for the casual user.

If no -i or -ip option is used, input is taken from the standard input. The output image is always written to standard output, which should be redirected.


To create a false color image directly from rpict(1):

rpict -vf default.vp scene.oct | falsecolor > scene.pic

To create a logarithmic contour plot of illuminance values on a Radiance image:

rpict -i -vf default.vp scene.oct > irrad.pic rpict -vf default.vp scene.oct > rad.pic falsecolor -i irrad.pic -p rad.pic -cl -log 2 -l Lux > lux.pic


Greg Ward


Work on this program was initiated and sponsored by the LESO group at EPFL in Switzerland.


getinfo(1), pcomb(1), pcompos(1), pextrem(1), pfilt(1), pflip(1), protate(1), psign(1), rpict(1), ximage(1)

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