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Last Updated:
Jan 20th, 2007 - 12:55:03 |
The channel mixer is a no fuss yet effective means of converting a color photo to a black and white image. It is used by professionals and amateurs alike.
Open your image and choose Layer> New Adjustment Layer> Channel Mixer
Click Monochrome to convert the channels to black and white. Ensure Preview is checked.
Photoshop defaults to 100% red which is usually too extreme for most images.
As a starting point type the following values into each channel
Red: 30% Green: 59% Blue: 11%
These values are said to represent the luminosity perceived by the human eye, and is a great starting point form which to make adjustments for any image. To aid in workflow, save these values as a preset so they can be loaded when needed.
You can now tweak the values to balance each channel for a look that is most pleasing. You can change the Constant slider to affect overall brightness
To ensure the most optimal result, the red, green and blue percentages should equal roughly 100%
In this instance adjustments have been made - with the percentages still equal to 100%
You can then save the image and if required create a further adjustment layer to tweak contrast or curves.
More examples:
The channel mixer is particularly useful for emulating the effects of colored lens filters used on black and white film. You will need to adjust these according to your image but this is a useful guide for a starting point.
R G B
Green filter: 14 58 33
Yellow: 58 20 22
Orange #1: 80 22 0
Orange #2: 65 20 12
Red #1: 100 0 0
Red #2: 75 25 0
Red #3: 140 -20 -20
Red #4: 155 -20 -35
Normal #1: 24 68 8
Normal #2: 43 36 30
High contrast: 40 32 60
Other sources of information:
http://www.outbackphoto.com/workshop/channelmixer/channelmixer.html
http://www.thelightsrightstudio.com/TLRB&WConversion.htm
© Copyright 2003-2005 by Scrapbook-Bytes; & original creator/s of tutorials/articles
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