Search found 43 matches

by tom_dl
2015-05-13T03:32:59-07:00
Forum: Users
Topic: Making a new 16-bit Lab color
Replies: 5
Views: 3477

Re: Making a new 16-bit Lab color

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 and ou...
by tom_dl
2015-05-13T01:35:51-07:00
Forum: Users
Topic: Making a new 16-bit Lab color
Replies: 5
Views: 3477

Re: Making a new 16-bit Lab color

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?
by tom_dl
2015-05-12T11:18:51-07:00
Forum: Users
Topic: Making a new 16-bit Lab color
Replies: 5
Views: 3477

Making a new 16-bit Lab color

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: 0,16256,16256 If I ...
by tom_dl
2015-04-28T08:50:50-07:00
Forum: Users
Topic: Issue with resize percentage (DDS)
Replies: 3
Views: 2815

Re: Issue with resize percentage (DDS)

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

Code: Select all

mogrify *.dds -filter Mitchell -resize 50%% -sharpen 1 *.dds
by tom_dl
2015-04-28T08:29:49-07:00
Forum: Users
Topic: Photoshop color conversion vs IM color conversion
Replies: 3
Views: 2295

Re: Photoshop color conversion vs IM color conversion

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 ...
by tom_dl
2015-04-28T05:21:52-07:00
Forum: Users
Topic: Photoshop color conversion vs IM color conversion
Replies: 3
Views: 2295

Photoshop color conversion vs IM color conversion

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...
by tom_dl
2015-03-20T05:28:06-07:00
Forum: Users
Topic: Average location
Replies: 1
Views: 1476

Average location

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 the...
by tom_dl
2015-03-20T05:11:13-07:00
Forum: Users
Topic: Photoshop blending mode "Darker color"?
Replies: 2
Views: 2690

Re: Photoshop blending mode "Darker color"?

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 weren't in eit...
by tom_dl
2015-03-12T09:03:41-07:00
Forum: Users
Topic: LAB channels don't behave during threshold
Replies: 3
Views: 2965

Re: LAB channels don't behave during threshold

@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!
by tom_dl
2015-02-26T10:56:54-07:00
Forum: Users
Topic: Threshold & separate outputs a bilevel rather than a grayscale
Replies: 4
Views: 3154

Re: Threshold & separate outputs a bilevel rather than a grayscale

I've tried:

Code: Select all

convert input.png -colorspace lab -channel G -separate -threshold 50% -channel G -separate -type grayscale output.png
to no avail, by the way.
by tom_dl
2015-02-26T10:40:18-07:00
Forum: Users
Topic: Threshold & separate outputs a bilevel rather than a grayscale
Replies: 4
Views: 3154

Threshold & separate outputs a bilevel rather than a grayscale

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...
by tom_dl
2015-02-26T08:54:08-07:00
Forum: Users
Topic: LAB channels don't behave during threshold
Replies: 3
Views: 2965

Re: LAB channels don't behave during threshold

Turns out I needed to -separate again:

Code: Select all

convert input.png -colorspace lab -channel G -separate -threshold 50% -channel G -separate output.png
Thought I'd leave this here for anyone else confused by separating channels.
by tom_dl
2015-02-26T08:43:20-07:00
Forum: Users
Topic: LAB channels don't behave during threshold
Replies: 3
Views: 2965

LAB channels don't behave during threshold

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 should ...