How to determine the brightness of an area in a picture

[Wolfgang]

Hello,

I am new to this board. I searched for an answer but I didn't find any.

I use convert to put some text into pictures. Is there any way to determine the brightness and/or the colour within the targeted area of the picture, so that the colour of the text can be set appropriately?

Thanks in advance.

[Bonzo]

One method would be to crop the area of an image you want the details for, resize it smaller, and use -identify.

How you get the information from -identify would depend on what you were using e.g. command line, php Perl etc.

[Wolfgang]

One method would be to crop the area of an image you want the details for, resize it smaller, and use -identify.

That sounds promissing.

How you get the information from -identify would depend on what you were using e.g. command line, php Perl etc.

I want to do this in a shell script (thus: command line) on Linux.

Can you tell me where I can find more information about this? Are there any examples available?

[Slig]

I want to do this in a shell script (thus: command line) on Linux.

Can you tell me where I can find more information about this? Are there any examples available?

You can take a look at this lots of shell scripts. I'm almost sure you'll find how to get the return of identify: http://www.fmwconcepts.com/imagemagick/index.php

[fmw42]

use

convert imagename.suffix[widthxheight+xoffset+yoffset] -verbose info:

See:
http://www.imagemagick.org/script/comma ... essing.php
http://www.imagemagick.org/Usage/files/#info
http://www.imagemagick.org/Usage/scripts/
http://www.cit.gu.edu.au/~anthony/info/ ... ript.hints

[anthony]

For brightness convert it to gray scale, and for outputing colors the txt: output is simplier

Code: Select all

  convert image -crop WxH+X+Y -resize 1x1\! -colorspace gray txt: