Legacy ImageMagick Discussions Archive

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.

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

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

Legacy ImageMagick Discussions Archive

MagickLevelImage parameters

MagickLevelImage parameters

Re: MagickLevelImage parameters

Re: MagickLevelImage parameters