Legacy ImageMagick Discussions Archive

After trying out your advice, I can conclude two things: * Using decimal precision does indeed work, so I can reach my desired values by using (0,-0.87109,0.79067) * As alluded to above, negative values do seem to work (for a & b channels, at least) in non-HDRI mode If you use -colorspace lab an...

That's very helpful, thanks! I'll use that format instead. Just out of curiosity, how come my second line (0,-2,2) works with negative values, when I'm not in HDRI mode?

Version: ImageMagick 6.9.0-10 Q16 x64 Hi, I'm having trouble setting the canvas a very specific color. The line I want to use would look like this: convert -depth 16 -size 2700x5120 -colorspace lab xc:"lab(0,-223,204)" output.tif But that produces the following 16-bit Lab values: 0,16256,1...

Also, is your -filter aimed at the -resize command? If so, it should appear before, not after:

The solution for matching PS was: convert input.tif -profile myprofile.icc -intent relative -black-point-compensation -profile sRGB.icc output.tif even though in PS I had converted from myprofile.icc to sRGB via Perceptual intent! When I wrote: If I use -black-point-compensation and -intent options ...

Version: ImageMagick 6.9.0-10 Q16 x64 I have created an ICC profile that I apply to my images. I use this command to apply it to my TIFF files (hitherto without profile): convert input.tif -profile myprofile.icc output.tif When I open output.tif in Photoshop, Photoshop notices the profile and displa...

I'm trying to use ImageMagick to find the location of a calibration target in an image. I've written enough code to output a b&w (i.e. bilevel, not grayscale) image, which looks like a small black square on a giant white background. I've used the following code to find the location of the all of...

Darker color compares RGB (total) from image A and with RGB (total) from image B and chooses the pixel with the lower total value. This way, no new colors appear in the composited image. This is different from "Darken" which does this on a per channel basis, often creating colors that were...

@Snibgo - thanks very much for your answers. I didn't realise PNG didn't support Lab, so tricking imagemagick didn't cross my mind. Great solution!

I've tried:
to no avail, by the way.

When I threshold a channel and then use -separate to save only this channel, the image I get is in 'bilevel' mode (acording to identify), rather than grayscale. I use this line: convert input.png -colorspace lab -channel G -separate -threshold 50% -channel G -separate output.png And obviously I'm ex...

Turns out I needed to -separate again:
Thought I'd leave this here for anyone else confused by separating channels.

I'm having trouble getting the result I want while using ImageMagick 6.8.9-5 Q16 x64 on Windows 7 64bit via Cygwin. I want to take an input image, convert it to LAB colorspace, apply a threshold on the 'A' channel, and output this as a grayscale (more specifically black&white, as a threshold sho...