June 16th, 2009 by Rolf

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It’s toning time again. Toning is done do black and white images to increase their “volume”, the perceived contrast range. We only have 256 values on the screen, so a bit of colour can be good.
In #39 I had shown how to make a Duotone or Tritone out of a monochrome image. And then Paul Wellner Bou showed in his Blog an easier way to do this.
It’s working, but why? To answer that, I look into the HSV colour model and try to explain the effects of the different layer modes.
A little bit about sharpening in an extra layer with “value” as the mode and a pointer to faking analog camera frames in digital images with a script and an original Hasselblad frame made by Marcus Ranum are at the end of the episode.
The TOC
01:00 Toning images
02:00 Toning enhances the visual volume
03:50 The recipe for a duotone
04:30 Adding a layer in colour mode and adding a layer mask from an image copy
07:00 Doing the same for the second tone
08:00 Inverting the mask
09:20 Switching layers on and off
10:30 Sharpening in Value mode
12:20 Unsharp mask
15:10 Explanation of Colour and Value mode
17:10 HSV colour model
20:00 A fake view camera frame
22:20 Multiply mode
23:40 A real Hasselblad frame

Meet the GIMP Video Podcast by Rolf Steinort and Philippe Demartin is licensed under a Creative Commons Attribution-Share Alike 3.0 Germany License.
Permissions beyond the scope of this license may be available at http://meetthegimp.org.
Tags: color mode, colour mode, duotone, frame, hasselblad, layer mask, layer mode, toning, value mode
Posted in Gimp, Gimp video tutorial | 14 Comments »
August 3rd, 2007 by Rolf

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In this episode of my video podcast I show how to correct colours with layers in GIMP.
For reducing the green tint of the image I add a layer filled with a bright magenta (white minus a bit green) and set the layer mode to “multiply”. This reduces the green in the image proportional to the amount of green in each pixel. The amount of the effect can be adjusted by changing the opacity of the layer or changing the colour of the layer.
Then I add a bit of blue with a layer filled with a very dark blue (black plus a bit blue) and set the layer mode to “screen”. Now the blue in each pixel is enhanced proportionally. This can also be adjusted.

Please let me know what you think about the show. Too slow? Too fast? Too much ramblings? Or too much information? Even if you like everything – write a comment or drop me a mail at info@meetthegimp.org
You can leave your comments on this blog or go to the Tips from the Top Floor Forum.
The TOC
00:22 Welcome
00:43 Correcting colour using curves
01:43 Correcting colour using a layer
02:28 Multiply layer
03:25 Change the colour of the multiply layer
04:39 Adjust the ammount of correction using opacity
05:30 Adding blue
05:52 Screen mode layer
08:07 The End
TOC made by paynekj

This work is licensed under a
Creative Commons Attribution-Share Alike 2.0 Germany License.
Tags: colour tint correction, layer mode, multiply mode, screen mode
Posted in Gimp, Gimp video tutorial | 11 Comments »