Calculate the average colour of an area in an image

Question

The goal is to lay a caption on top of an image and set the text colour to one that will contrast with the background it is positioned on top of. To that end, I wish to calculat

Answer 1

Here is a command that handles both cropping and color detection, and also produces output in a consistent R,G,B format:

 convert image.gif -crop 6x7+8+9 -resize 1x1\! -format "%[fx:int(255*r+.5)],%[fx:int(255*g+.5)],%[fx:int(255*b+.5)]" info:-

where, in 6x7+8+9 :

 6: image width (pixels)
 7: image height (pixels)
 8: x-coordinate of top left corner
 9: y-coordinate of top left corner

Returns

 176,191,67

Adapted from https://stackoverflow.com/a/25488429/3124680