Legacy ImageMagick Discussions Archive

Is there a way to ask for the RGB values of a pixel at location X, Y?

Is there a way to ask for the RGB values of a pixel at location X, Y?

What are you using? The command-line, PerlMagick, MagickCore, MagickWand, Magick++, iMagick? The answer depends on your interface to ImageMagick.

The command line.

convert rose.png[1x1+10+10] txt:
# ImageMagick pixel enumeration: 1,1,65535,rgb
0,0: (18504,16448,14649) #484840403939 rgb(72,64,57)

or

convert rose.png[1x1+10+10] -format "%[fx:int(255*r)],%[fx:int(255*g)],%[fx:int(255*b)]" info:
72,64,57

I don't understand this [1x1+10+10]

What does this mean?

It is a subsection of the image that is 1x1 pixel at offset x=10 and y=10 from the upper left corner.

see
http://www.imagemagick.org/script/comma ... essing.php
http://www.imagemagick.org/Usage/files/#read_mods

you can also do it this way:

convert rose.png -format "%[fx:int(255*p{10,10}.r)],%[fx:int(255*p{10,10}.g)],%[fx:int(255*p{10,10}.b)]" info:
72,64,57

see
http://www.imagemagick.org/script/fx.php
http://www.imagemagick.org/Usage/transform/#fx_escapes

If you are on Windows, see
http://www.imagemagick.org/Usage/windows/

drewvy wrote:I don't understand this [1x1+10+10]

Its a crop done immediateally after reading, before the image is added to the current image sequence in memory.

Equivelent to just faster.

NOTE you may have to quote the square brackets as it is a 'shell meta-charcater'
so the original command should have been... Another alternative is Though that may produce a color name, instead of the pixels RGB values. For a 16 bit image it may also use percent values in the RGB value it returns. Fred's more complex method gurantees the return of a the 8bit RGB values.

For more methdos and information see
IM Examples, Color Quantization and Dithering, Extracting Colors
http://www.imagemagick.org/Usage/quantize/#extract