Photoshop Tutorials - Working with Channels
Working with Channels
Open any image in Photoshop. In the title of the image window you will see the file name and the color model. Most likely, it is RGB. RGB images have three channels: Red, Green and Blue (their names contributed to the name of the color model). The main idea of RGB color model is that any color can be presented as the certain combination of these three colors.
To learn more about the way channels interact let us check the box Color Channels In Color that can be located at Edit > Preferences > Display and Cursors. We strongly recommend you not to work with Channels palette when this option is checked because your eyes will get tired very soon, but it is gives a good understanding of the RGB color model though. However, let us continue for now - you will remove the checkbox later on.
Open the Channels panel. The color channels are presented in respective colors (if you have Color Channels in Color option checked).
The top line shows the combination of three channels. It allows you to see the overall effect of editing any of the channels and to edit all three channels simultaneously. The channels selected for preview or editing are called active channels. All of the changes are made to the active channels. They are highlighted in the channels palette. By default, the active channel is the one that combines all three. You can click on Red, Blue or Green to select the one you want to edit. The document will become colored in respective color. You can click them one after another to see how the image will change.
To select more that one channel keep Shift button pressed and click the desired channels. The eye icon allows you to make the channels visible or invisible. The visible channel and active channel are not same things in Photoshop. Having one of the color channels selected click on the eye icon by the combined channel. The same channel will remain active but you will see all of the three channels.
The buttons at the bottom of the channels palette are applied to additional alpha-channels so there is no need to discuss them in this tutorial.
So how many colors can be displayed with a color model? To save one color you will need one byte or eight bits. The total amount is equal to 16,6 million colors.