Convert from CMYK: Multi-channel mode and special effects

CMYK to multiple channels

Multi-channel patterns are usually present as intermediate transition modes for channel splitting and merging. In the opening section of this chapter, the reader has rehearsed the different effects of the channels under different combinations of rules (RGB, Lab, or CMYK).

A much larger use of multichannel mode is in printing. If you convert a CMYK-mode image to multichannel mode, CMYK cyan, magenta, yellow, and black channels are converted to 4 spot channels, and different special effects can be combined due to the different characteristics of the spot color channel and the characteristics of the multi-channel mode that distinguishes it from other channels.

1th Step

Open a CMYK-mode image and open its channel palette.

2nd Step

Open the Channel Palette menu, use the "Detach Channel" command, split 4 colors into 4 grayscale images, and then open any of the grayscale image of the Channel Palette menu, using the Merge Channel command, select the merged image for multichannel mode.

3rd Step

The generated multichannel pattern image is composed of 4 channels, "ALPHA1" to "ALPHA4" respectively.

4th step

Double-click the channel thumbnail and eject the Channel Options dialog box and select the Spot color option. Click the color box below the left, pop the color picker, select the Customize button, and go to the Custom Color dialog box, where users can specify spot colors.

5th step

4 spot colors are specified for 4 channels: PANTONE process Cyanc, PANTONE process Magentac, PANTONE process YELLOWC, and PANTONE process BLACKC. The density is all 50%.

6th step

Although these 4 spot colors are the same as the 4 color versions of CMYK mode, they render a different color appearance than the CMYK mode image.

The color pattern image that the reader touches before, whether RGB or CMYK, its color channel cannot change arbitrarily, but multi-channel mode can change arbitrarily. For example, you can swap the PANTONE process YELLOWC and PANTONE process MAGENTAC.

The position of the channel in the palette determines the order of its printing, and the top channel is printed first. For example, if the channel is arranged in the order of PANTONE process Cyanc, PANTONE process Magentac, PANTONE process YELLOWC, PANTONE process BLACKC, then PANTONE Process Cyanc first printed, PANTONE process BLACKC final printing. As a result of printing ink will always cover off a part of the first printed ink, so the final image of the appearance of cyan, the composition of the yellow and black components, the image of black and yellow tones. As shown in the figure is the spot color combination effect for some multichannel modes.