Jay Arraich’s Photoshop Tips


	Channels page three When you open an RGB, or CMYK color mode image in Photoshop, there are color channels created for each of those color components. Each of those individual color channels is a map which tells Photoshop “How Much?” of that color is applied to each pixel in the image. For example, if I want to look at just the Blue information for an image, I would click on the Blue channel’s name to select it, and turn off the ‘eyeball’ for all the other channels by clicking on the eye icon next to each of those channels. You would see the grayscale image, shown below. This is the map of all the blue pixels in this photograph.	back next start Tips 7 Tools 7 Palettes
Tutorials Brushes in 7 Using PS7 Brushes 7 Basics 7 Reference: Tools 7 Reference: Palettes Reference: Filters Reference: Effects Selections Channels Basic Layers Basic Pen How Much? Color Management Color Correction Curves, Levels, or Brightness/Contrast? Combining Images Combining Images II Combining Images III Compositing in Photoshop Perfect Blend Multicolor Fill Dodge and Burn Duotones Styles On Masks Organic Textures Abstract Background Make a Frame 3D Wire Text Doodling
Older Tutorials Quick Mask Rubberstamping More Adjustments Sharpening Filters Color Elements Tutorials Elements Basics Reference: Elements Tools Reference: Elements Palettes How Do I...? Gotcha Pre-Beginner Pre-Beginner II Why Layers? Holes Fade In Playing With Styles Learning Effects Redeye Removal Artistic Filtering Symmetrical Flowers Simulated Alpha Channels Layer Masks Multilayer Masks Displacing Textures	The white flowers show a lot of blue content, as the color white is made up of the RGB values, R 255, G 255, and B 255, or max content of all three colors. The blue, which is the central color on the gradient at the bottom of the image, shows white as it is pure blue. The little “blue” flowers show as a light shade of gray. Pure colors rarely occur in nature. The flowers look blue to us, but, in reality there are other colors in them. In fact, the highest amount of blue I could find in the flower, by dragging with the Eyedropper, and watching the Info palette was this. As you can see, there is quite a lot of green, and red included in this flower. This color value came from near the center of the detail shown below. The blue channel detail of that flower follows.
	CMYK channels use black to indicate the areas where there is more of a color, and white to show where there is less. This is the reverse of the RGB channels, or your default alpha channel settings. For example, here is the yellow channel. The most yellow in the photograph occurs at the center of the big white flowers, a detail of which is shown here. As you can see, the yellow part is displayed as black. The black channel in CMYK, which is the K channel, is shown below. Again, to repeat, in the CMYK channels, white indicates areas where there is none of the color, and black indicates areas which are filled with it. You should not delete any of your color channels, but you can edit them using the various Image > Adjust commands such as Levels, and Curves, and filters such as the Unsharp Mask, and Gaussian Blur. Sometimes image problems are specific to one of the color channels and can be corrected more subtly by working, specifically on that color’s channel. Be careful, though. This is not for beginners. In addition, color channels can be used to make selections. If you have a distinctly colored object which would be very difficult to select, such as flying hair, or a tree with a million leaves, check the color channels. If one of them shows your object as clearly defined, and distinct from the background load that channel as a selection, and then use the Lasso tool with the Subtract from Selection option to remove unwanted areas from the selection. *Continue on page four*
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Channels

Copyright © 2004 by Jay Arraich. All rights reserved. All photographs copyright ©2004 by Jay Arraich jay@arraich.com

Copyright © 2004 by Jay Arraich.
All rights reserved.
All photographs copyright ©2004 by Jay Arraich
jay@arraich.com