MagickLevelImage parameters

[aditan22]

Reading Anthony's ImageMagick Examples here: http://www.imagemagick.org/Usage/color/#levels

While adjusting the black and white 'points' inward will increase the overall contrast of the image, a little...

convert rose: -level 5%,95%,1.0 rose_contrast.gif

Or increase the contrast a LOT...

convert rose: -level 20%,80%,1.0 rose_contrast2.gif

How to implement this in MagickWand PHP? I know there's a function MagickLevelImage, but it seems I cannot use percentage in the function's parameters.

[sambessey]

Yep I can't get this to work either... The image is always white. Could you be a bit more specific in what parameters it accepts please?

Thanks

[el_supremo]

The IM source code implies that the inputs are within the quantum range, so if you wanted to pass arguments equivalent to "-level 5%,95%,1.0", In C you would use (I presume PHP is similar):

Code: Select all

	MagickLevelImage(magick_wand,5*QuantumRange/100,1.0,95*QuantumRange/100);

Note that the arguments are black_point, gamma, white_point


Pete