Legacy ImageMagick Discussions Archive

I would like to put a small watermark on images.

I would like the color of the text to be an inversion of the colors below it, on a pixel by pixel level, thereby insuring it showed up on everything.

Is this possible?

I would guess you would need to create a mask of your watermark - select the part of the image your watermark covers - negate it then composite it back. I do not know how good it would look though.

Thanks. Would there be any sane way to do this with annotate or something similarly simple? The text is just pixel text.

try these. as bonzo has suggested, you need to create a mask from your text and use it to composite the image and its negative


convert \( rose: -resize 400% \) \( -clone 0 -negate \) \
\( -clone 0 -fill black -colorize 100% -fill white \
-font arial -pointsize 48 -gravity center -annotate +0+0 "TESTING" \) \
-compose over -composite rose_test.png

convert \( rose: -resize 400% \) \( -clone 0 -negate \) \
\( -clone 0 -fill black -colorize 100% -fill white \
-font arial -pointsize 48 -gravity center -annotate +0+0 "TESTING" \) \
-compose dissolve -define compose:args=50,100 -composite rose_test2.png

I resized the rose: IM internal image to make it larger so that I could use a bigger font for demonstration.

Great work, Fred! Thanks!

If you use 'difference' composition with a mask. Black remains normal, white becomes negated.
http://www.imagemagick.org/Usage/compose/#difference

However with any negation method perfect grays will always remain unchanged.

This is which watermarks that both lighten and darken images are often a better option. It removes the possibility of having no effect for some specific color in the image.

Good point. Perhaps a shadow under that annotation?

If you are wanting annotation rather than watermarking, look at IM examples, Annotations
http://www.imagemagick.org/Usage/annotating/