Search found 188 matches

by henrywho
2012-04-11T01:49:00-07:00
Forum: Users
Topic: Is "-colorspace" usage changed again in IM 6.7.6-5 Q16?
Replies: 4
Views: 7852

Re: Is "-colorspace" usage changed again in IM 6.7.6-5 Q16?

That's case (3) in my first post, where I got a dark image.

Actually, I suspect that it is a bug in the (various) Windows build of 6.7.6-5 Q16.
by henrywho
2012-04-09T15:49:32-07:00
Forum: Users
Topic: Is "-colorspace" usage changed again in IM 6.7.6-5 Q16?
Replies: 4
Views: 7852

Re: Is "-colorspace" usage changed again in IM 6.7.6-5 Q16?

Also too dark -> convert test.jpg -colorspace sRGB -distort Resize 25% -colorspace RGB -quality 95% test_out4.jpg
by henrywho
2012-04-09T08:10:09-07:00
Forum: Users
Topic: Is "-colorspace" usage changed again in IM 6.7.6-5 Q16?
Replies: 4
Views: 7852

Is "-colorspace" usage changed again in IM 6.7.6-5 Q16?

Okay -> convert test.jpg -distort Resize 25% -quality 95% test_out1.jpg Okay -> convert test.jpg -gamma 0.4545454545454545 -distort Resize 25% -gamma 2.2 -quality 95% test_out2.jpg Too dark -> convert test.jpg -colorspace RGB -distort Resize 25% -colorspace sRGB -quality 95% test_out3.jpg .... teste...
by henrywho
2012-04-08T08:50:55-07:00
Forum: Users
Topic: Alternative to modulate command to increase Saturation
Replies: 40
Views: 64219

Re: Alternative to modulate command to increase Saturation

I thought "blend" also assumes linear RGB. 8)
by henrywho
2012-04-05T08:14:27-07:00
Forum: Users
Topic: Alternative to modulate command to increase Saturation
Replies: 40
Views: 64219

Re: Alternative to modulate command to increase Saturation

convert INPUT.JPG ( +clone -colorspace Gray ) +swap -compose Blend -set option:compose:args 250 -composite OUTPUT.JPG Seems the change in brightness can be better controlled if we add the "-colorspace" pair. convert INPUT.JPG -colorspace RGB ( +clone -colorspace Gray ) +swap -compose Blen...
by henrywho
2012-04-04T17:56:24-07:00
Forum: Users
Topic: RGB to grayscale with red=0,blue=255
Replies: 5
Views: 11410

Re: RGB to grayscale with red=0,blue=255

Not really sure what you wanna do, but the following looks similar to your sample output:

Code: Select all

convert.exe k1s1mb.gif -gamma 1.6 -color-matrix "1 -0.5 0 1 -0.5 0 1 -0.5 0" -gamma 0.625 -quality 05 k1s1mb_gray.png
Adjust the pair of gamma values till it looks good for you.
by henrywho
2012-04-04T00:34:14-07:00
Forum: Users
Topic: Alternative to modulate command to increase Saturation
Replies: 40
Views: 64219

Re: Alternative to modulate command to increase Saturation

Just tested using "Surfing in Hawaii" in http://en.wikipedia.org/wiki/Saturation_%28color_theory%29 The matrix (MATCIE) made from CIE RGB-XYZ weights is actually performing quite well when compared with "LCh chroma (see CIELAB) increased by 50% in Photoshop", marginally better th...
by henrywho
2012-04-03T18:52:24-07:00
Forum: Users
Topic: Alternative to modulate command to increase Saturation
Replies: 40
Views: 64219

Re: Alternative to modulate command to increase Saturation

If we want a change the saturation or hue without changing intensity/brightness/intensity/luma/whatsoever, it seems we need to settle on a good definition.

btw, is "-colorspace LAB -channel R -separate" also assuming linear RGB?
by henrywho
2012-04-03T10:49:34-07:00
Forum: Users
Topic: Alternative to modulate command to increase Saturation
Replies: 40
Views: 64219

Re: Alternative to modulate command to increase Saturation

On further tests, the color matrices generated from the second row of the sRGB (linear) to CIE XYZ matrix found in http://en.wikipedia.org/wiki/SRGB give better result with "red" being less profound than other weightings Color matrix updated: https://docs.google.com/spreadsheet/ccc?key=0Ag...
by henrywho
2012-04-03T04:53:16-07:00
Forum: Users
Topic: Alternative to modulate command to increase Saturation
Replies: 40
Views: 64219

Re: Alternative to modulate command to increase Saturation

Thank you for your advise on "MPC". Actually, I have one question on "modulate". The below commands are giving different outputs. Which usage is correct? convert.exe imput.png -colorspace RGB -distort resize 25% -modulate 100,120 -colorspace sRGB output_1.png convert.exe imput.pn...
by henrywho
2012-04-03T04:24:21-07:00
Forum: Users
Topic: How?: colorspace/gamma aware resize for Grayscale Images
Replies: 8
Views: 25733

Re: How?: colorspace/gamma aware resize for Grayscale Images

anthony wrote:On the other hand, assuming the image is linear-RGB and converting to sRGB does not have this problem.

Code: Select all

    convert im/img_photos/rings_lg_orig.png -set colorspace RGB -colorspace sRGB test_sRGB.png
Giving a gray image, but the result is too bright.
by henrywho
2012-04-03T00:26:17-07:00
Forum: Users
Topic: Alternative to modulate command to increase Saturation
Replies: 40
Views: 64219

Re: Alternative to modulate command to increase Saturation

The simple 1.2/-0.1/-0.1 vivid matrix will change the luminance and so I prefer the more complicated matrix. Thanks for reminding about the redundant "-depth" parameters. They always appear in my command-lines because my scripts are generating intermediate MIFF files and I want them having...
by henrywho
2012-04-02T21:46:05-07:00
Forum: Users
Topic: Alternative to modulate command to increase Saturation
Replies: 40
Views: 64219

Re: Alternative to modulate command to increase Saturation

To calculate the matrix, I use this spreadsheet: https://docs.google.com/spreadsheet/ccc?key=0AgwlupmDRV3QdFBuTWJVMUtJci15c2FKd1M3SE9IQUE convert input.png -depth 16 -colorspace RGB -distort Resize 25% -sigmoidal-contrast 3,27% -color-matrix "1.1575 -0.14308 -0.01442 -0.0425 1.05692 -0.01442 -0...
by henrywho
2012-04-02T19:59:44-07:00
Forum: Users
Topic: How?: colorspace/gamma aware resize for Grayscale Images
Replies: 8
Views: 25733

Re: How?: colorspace/gamma aware resize for Grayscale Images

[3] gives me a color image. That's why I said it is totally incorrect.

Together with a trivial "convert.exe rings_lg_orig_as_24bit.png directsave.png" giving a 8bit grayscale PNG (rings_lg_orig_as_24bit.png is the 8bit PNG converted to a gray-only 24bit RGB PNG), it appears a bug to me.
by henrywho
2012-04-02T18:56:23-07:00
Forum: Users
Topic: How?: colorspace/gamma aware resize for Grayscale Images
Replies: 8
Views: 25733

Re: How?: colorspace/gamma aware resize for Grayscale Images

fmw42 wrote:convert rings_lg_orig.png -type truecolor -depth 16 -colorspace RGB -distort resize 150x150! -colorspace sRGB -depth 8 06b.png
No, the result is too bright. It gives the same result as combining three PNG.