Application of Channels in Photoshop (2)

4) Merge images

Use the Merge Channels command to merge separate channels, or combine multiple grayscale images into one image.

Spot channels can be merged directly into each primary channel. Spot colors can be converted to color channels and merged with color channels. The original spot color channel will be deleted.

Merging spot color channels will merge multiple layers of images, and the combined composite channel reflects previewed spot color information. In addition, the results of spot color channel merging usually do not reproduce the same color as the original spot color channel because CMYK inks cannot exhibit the color range of spot color inks. If you want to output a spot color channel, you need to save the file in Photoshop DCS2.0 (EPS) format.

note:

1 All the merged images must be in "grayscale" mode and open in the workspace;
2 all merged images must have the same pixel size;
The number of 3 grayscale images must be equal to the number of channels of the color mode that you want to merge. If RGB mode requires 3 grayscale files, CMYK mode requires 4 grayscale files.
4 Cannot separate and recompose images with a spot color channel, and the spot color channel will be added as an alpha channel.

5) Composite image

With the channel "compute" command, you can merge two channels from the same image or two images with the same size and resolution, and save the result to a new image or a new channel in the current image. In addition, you can directly convert the result to a constituency.

6) Analyze the image in a single channel and search for a selection

Since the constituency is obtained directly from the channel mask data, the constituency path obtained by this method is far more accurate than that obtained by other methods (such as the magic wand tool, color range, or extraction command), and it contains details. And the level of accuracy.

7) The output channel information is increased or decreased according to other channel information of the image itself

The channel mixer uses the channel as the object of action (output channel) and increases or decreases according to the source channel information. For a pixel's color information, it can be calculated based on its own channel network point information, or it can be calculated using the information of other channels. Use it to add color information that does not originally exist in the image, or to change certain colors of the image proportionally.

8) Change the saturation of the image

Adding black or increasing the opposite color dot can reduce the saturation of the image. With the channel mixer, you can increase (decrease) black in the color to change the saturation of the image.

9) Protect the clarity of the image

Sometimes, there are noises in the image, which can be processed separately according to the noise of each channel of CMYK. This no-noise channel maintains the clarity of the original image.

4 Channel Application Considerations

In the document drop-down list box, only images with the same resolution and size as the current file can be displayed. The default value is the file where the channel is located. In addition, the main channel cannot be copied.

After one or several channels are selected on the image, the editing operation on the image only affects the currently visible channel.

The color information channels are always at the top of the channel palette and their order cannot be changed.

The mask channel has 256 possible grayscale values, just like other grayscale images.


If the user deletes a primary color channel, the color mode of the channel will change to multi-channel mode. Photoshop does not allow printing of color composite images in Multichannel mode, and most output file formats do not support multichannel mode images.

Before executing the "separate channel" command, all layers in the image with multiple layers should be combined first, otherwise this command cannot be used. After the separated channels are edited and modified, the channels can be merged. When merging channels, if you want the alpha channels to merge together, enter the total number of channels in the Channel Edit box in the Merge dialog box. However, in this way, the merged image child no longer has color information (ie, a grayscale image).

If you want to apply a spot color as a hue to the entire image, you need to convert the image to two-tone mode and apply a spot color on one of the two-tone plates. Up to four spot colors can be used, one for each plate.

If you want to use a spot color for a specific area of ​​the image, you must create a spot color channel.

Spot colors cannot be used for a single layer.

If you print an image containing a spot color channel to a composite printer, the spot color is printed as an additional page.

Spot channels can be merged with color channels and spot colors can be used as components of color channels. When you combine spot channels, you can print a one-page proof of a spot color image on a desktop printer.

You cannot move the spot channel to the default channel in the channel palette unless in multichannel mode.

Source: "Printing World" Author: Liu Xiaoxia clean