Meet the GIMP #33: The Channel Mixer - Monochrome conversion (2)

Posted in Graphics on April 22, 2009

Meet the GIMP #33: The Channel Mixer - Monochrome conversion (2)

I promised a better way to convert coloured images to monochrome. And here is the Channel Mixer. It allows you to mix the amount of the red, green and blue channel of an RGB image and change the appearance dramatically. The image to the left is an example that I stole from a terrific website Cambridge in Colour. You see the original (in colour) and some outputs of the channel mixer.

Then I tackle the “double face” from episode 31 again. I convert the new passport image with the channel mixer and get a better skin tone. Adding the same colour tint to both halves of the image and getting rid of the grain by blurring give a better result than before.

But the channel mixer is not the final stop on the road to the “perfect” monochrome image. Next week I’ll use layers and the curves tool to get an even better result. And then there are duotones and sepia….

Finally I start a new challenge for you. Do a monochrome conversion with GIMP, post the image in the photogroup at 23 and be sure to use the tag “mtg-monochrome”. The challenge ends March 31 1600GMT and I’ll draw a winner by random choice. No interview partner as a random generator- I’ll go high tech this time.

Some links from the video The TOC

00:34 Site statistics and plugging
04:12 Parrot example image
05:06 The problem with simple desaturation
06:00 Cambridge in Colour tutorials
09:56 Channel Mixer
11:20 - Average settings
11:47 - Preserve luminosity
14:32 Double face re-visited
15:00 - Convert to monochrome using the channel mixer
17:57 - Colour matching
19:00 - Curves adjustment
20:01 - Blur the grain
21:52 The Gimp web-site
23:10 Next episode - a better way
23:44 The Black and White Challenge
26:59 The End

TOC made by paynekj

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Tags: Design, GIMP, Meet the GIMP, Broadcasting, Screencasts, b&w, monochrome, channel mixer