Fred's ImageMagick Scripts



 

 

HUEMAP


Transforms the hues in an image from one range to another.

Download Script

last modified: November 27, 2011



USAGE: huemap [-h hues] [-t tolers] [-r] infile outfile
USAGE: huemap [-help]

-h .... hues ....... hues=srchue,dsthue; source and destination hue values;
.................... comma separated list; 0<=integer<=360; default=240,120
.................... maps blue to green
-t .... tolers ..... tolers=stoler,dtoler; source and destination range of
.................... hues on each side of hue values; 0<=integer<=360;
.................... default=10,10
-r reverse direction of range of destination hues

PURPOSE: To transform the hues in an image from one range to another.

DESCRIPTION: HUEMAP transform the hues in an image from one range to another. One hue can be mapped to another single hue. One range of hues can be mapped to a single hue. Or one range of hues can be mapped to another range of hues. This is similar to GIMP's Rotate Hues.

ARGUMENTS:

-h hues ... HUES=SRCHUE,DSTHUE. These are source and destination hue values in the range of 0<=integer<=360. The source hue (range) will be replaced by the detination hue (range), depending upon the tolers values below. The default=240,120 maps blue to green.

-t tolers ... TOLERS=STOLER,DTOLER. These are the source and destination ranges on each side of the specified hues that determine the range of hues to be mapped. Values are in the range of 0<=integer<=360. The default=10,10.

-r ... REVERSE the direction of the range of destination hues.

REQUIREMENT: IM version 6.3.5-7 or higher due to the use of -clut.

NOTE: If the image has an alpha channel, it will be copied unchanged to the output image.

CAVEAT: No guarantee that this script will work on all platforms, nor that trapping of inconsistent parameters is complete and foolproof. Use At Your Own Risk.


REFERENCE CHART


convert \( -size 151x151 xc:"rgb(100%,0%,0%)" -colorspace hsl \) \
\( -size 100x300 gradient: -rotate 90 +distort Polar '75,0,.5,.5' +repage -rotate 90 \) \
-compose CopyRed -composite -colorspace RGB \
\( -size 151x151 xc:black -fill white -draw "circle 75.5,75.5 75.5,151" -alpha off \) \
-compose copy_opacity -composite polar_rainbow_white.jpg


EXAMPLES


Original Image

Original Image
(http://phong.informatik.uni-leipzig.de/~kuska/oglscript/EarthMap.png)

 

Arguments:
-h 225,0 -t 50,0 		Arguments:
-h 225,0 -t 50,0

 

Arguments:
-h 225,0 -t 50,50 		Arguments:
-h 225,0 -t 50,50

 

Arguments:
-h 225,0 -t 50,50 -r 		Arguments:
-h 225,0 -t 50,50 -r

 

Arguments:
-h 225,120 -t 50,50 		Arguments:
-h 225,120 -t 50,50

 

Arguments:
-h 225,120 -t 50,50 -r 		Arguments:
-h 225,120 -t 50,50 -r

 

Arguments:
-h 60,300 -t 20,20 		Arguments:
-h 60,300 -t 20,20

 



What the script does is as follows:

  • Converts image to HSL colorspace and separates channels
  • Maps a range of values in the hue channel to another range of values
    using a modified gradient lut and -clut
  • Combines the HSL channels back to an RGB image

This is equivalent to the following IM commands.

  • convert $tmpI1 -colorspace HSL -channel R -separate $tmpH1
  • convert $tmpI1 -colorspace HSL -channel G -separate $tmpS1
  • convert $tmpI1 -colorspace HSL -channel B -separate $tmpL1
  • convert -size 1x360 gradient: -rotate 90 $tmpG1
  • dst1=`convert xc: -format "%[fx:($dsthue-$dtoler)]" info:`
  • dst2=`convert xc: -format "%[fx:($dsthue+$dtoler)]" info:`
  • len=$((2*$stoler+1))
  • dst1=`convert xc: -format "%[fx:100*$dst1/360]" info:`
  • dst2=`convert xc: -format "%[fx:100*$dst2/360]" info:`
  • convert -size ${len}x1 gradient:"gray($dst1%)"-"gray($dst2%)" \
    -channel red -evaluate set 0 +channel \
    -background none -gravity west -extent 360x1 $tmpT1
  • src1=`convert xc: -format "%[fx:$srchue-$stoler]" info:`
  • sign=`convert xc: -format "%[fx:sign($src1)<0?0:1]" info:`
  • abs_src1=`convert xc: -format "%[fx:abs($src1)]" info:`
  • if [ $sign -eq 0 ]; then
    rollval="-${abs_src1}+0"
    else
    rollval="+${abs_src1}+0"
    fi
  • convert $tmpG1 \( $tmpT1 -roll $rollval \) \
    -compose over -composite \
    -channel G -separate +channel \
    $tmpG1
  • convert $tmpH1 $tmpG1 -interpolate nearest-neighbor -clut $tmpH1
  • convert $tmpH1 $tmpS1 $tmpL1 -set colorspace HSL -combine \ -colorspace RGB $outfile