How to Use Channels in Photoshop

Image channels in an RGB Image

Photoshop is a powerful image editing and manipulation package that offers many useful tools for photographers. One of the often overlooked, but very useful, tools is channel editing. Images using the following color models have an available channel mixer--Red Green Blue (RGB); Cyan, Magenta, Yellow, blacK (CMYK) and Lab Color. Since RGB is the most common mode used in Photoshop, this article will use RGB for all examples.

Editing channels edits all primary colors in an image. Channels can be edited using the same filters and tools as are used on the full image, which can result in some fun and very interesting results. It is important to remember that when you make an edit that only applies to one channel, all image data of that color will be affected. For example, running a Gaussian blur on the "blue" channel will blur all blue data in the image. The red and green data will not be affected. Below are the essentials for using the "Channels" tool.

Instructions

1. Open "Photoshop."

2. Open an RGB image.

3. Select "Channels" under the "Windows" menu.

4. Select a channel to be edited by clicking the channel in the "Channels" tab. For example, to warm up an image a little, select "Red" by clicking the "Red" channel.

5. To see the effects of the channel changes, click the box next to "RGB" in the channel menu to make all three channels visible. The "Red" channel still should remain selected.

6. To warm up the image a little, select "Brightness/Contrast" from the "Adjustments" sub-menu of the "Image" menu. To warm the image up, increase the brightness and contrast to taste while watching the changes in the main image window.

7. Continue adjusting each image layer by following the above instructions with the other layers until the image is to your taste.

Tips & Warnings

• This technique is good for simulating old film, Holga or other lo-fi photography techniques.

• Interesting effects can be achieved by blurring certain channels while running edge enhancements on others.

• Experiment with channel edits and take notes of the results.

• Extreme edits to channels will make the colors unrealistic and surreal.