Mixing color channels (Photoshop)

The Channel Mixer command lets you create high-quality grayscale images by choosing the percentage contribution from each color channel. You can also create high-quality sepia-tone or other tinted images. Using the Channel Mixer, you can also make creative color adjustments not easily done with other color adjustment tools.

The Channel Mixer modifies a targeted (output) color channel using a mix of the existing (source) color channels in the image. Color channels are grayscale images representing the tonal values of the color components in an image (RGB or CMYK). With the Channel Mixer, you are adding or subtracting grayscale data from a source channel to the targeted channel. You are not adding or subtracting colors to a specific color component as you do with the Selective Color command. For more information about channels, see Using Channels, and for more information about the Selective Color command, see Using the Selective Color command (Photoshop).

To create monochrome images from RGB or CMYK images:

1. In the Channels palette, select the composite color channel.
2. Do one of the following to open the Channel Mixer dialog box:
• Choose Image > Adjustments > Channel Mixer.
• Choose Layer > New Adjustment Layer > Channel Mixer. Click OK in the New Layer dialog box.
3. Select the Monochrome option to set Gray as the output channel. This creates a color image that contains only gray values.
4. Use the Source Channels sliders to control the amount of detail and contrast in the images you plan to convert to grayscale.

Before adjusting the percentages of the source channels, view how the each source channel affects the monochrome image. For example, in RGB, view the image with the Red channel set to +100% and the Green and Blue source channels set to 0%. Then, view the image with the Green source channel set to +100% and the other two channels set to 0%. Finally, view the image with Blue source channel set to +100% and the other channels set to 0%. In adjusting the percentages of the source channels, the best results are often when the combined values of the source channels add up to 100%.

5. (Optional) If you select and then deselect the Monochrome option, you can modify the blend of each channel separately, creating a handtinted appearance.

Handtinted effect by selecting (left)/deselecting (right) the Monochrome option
6. (Optional) Drag the slider or enter a value for the Constant option. This option adjusts the grayscale value of the output channel. Negative values add more black, and positive values add more white. A -200% value makes the output channel completely black, and a +200% value makes the output channel completely white.

To mix color channels:

1. In the Channels palette, select the composite color channel.
2. Do one of the following to open the Channel Mixer dialog box:
• Choose Image > Adjustments > Channel Mixer.
• Choose Layer > New Adjustment Layer > Channel Mixer. Click OK in the New Layer dialog box.
3. For Output Channel, choose the channel in which to blend one or more existing (source) channels. For more information, see Using the Channels palette (Photoshop).

Choosing an output channel sets the source slider for that particular channel to 100% and all other channels to 0%. For example, choosing Red as the output channel sets the Source Channels sliders to 100% for Red, and 0% for Green and Blue (in an RGB image).

4. Drag any source channel's slider to the left to decrease the channel's contribution to the output channel or to the right to increase it, or enter a value between -200% and +200% in the text box. Using a negative value inverts the source channel before adding it to the output channel.
5. Drag the slider or enter a value for the Constant option. This option adjusts the grayscale value of the output channel. Negative values add more black, and positive values add more white. A -200% value makes the output channel completely black, and a +200% value makes the output channel completely white.

You can also save the settings you make in the Channel Mixer dialog box for reuse on other images. For more information on saving and loading settings, see Saving and reapplying settings.