How to Add Spot Colors in Photoshop Images (top)

In pre-press production, such problems often arise. Advertisers need to clearly express an object in the advertising image to achieve the purpose of highlighting the theme. How do you do it? Prior to Photoshop 5.0, adding spot colors to CMYK images was a headache.

Now, adding a spot color to Photoshop 5.0 is as easy as creating a new channel.

Channels are a basic concept in Photoshop. It can save the image's color, selected area, and transparency information. In Photoshop 5.0, channels can also save spot color information. Adding a spot color channel is simple, but if you want the best results, you should do some research and planning before you start to join the spot channel.

First of all, it is necessary to know whether the spot color image needs to be hollowed out; how to prevent the occurrence of moiré when the spot color ink is overprinted on other inks; and how to save the spot color image file if you want to import the spot color image into the layout software or the drawing software. The DCS2.0EPS file needs to be clear on the issue.

The problem to be considered is a bit more, but it does not matter. This article will answer all the above questions and help you to add spot color information to Photoshop images to achieve the desired effect.

Add spot color information

In Photoshop, there are several ways to add a spot color channel. You can create an empty spot channel, or create a spot color channel for the selected area, or convert an alpha channel to a spot color channel. No matter which method you use, the basic steps are the same:

1. Create a spot color channel

First, open the Channel Palette and create an empty spot color channel. Select New Channel Palette from the Channel Palette's menu; if a new channel is created in the selected area of ​​the image, first select an area on the image and select the Nwe Channel Palette command from the Channel Palette's menu; if you want to put an Alpha The channel becomes a spot color channel. First select the channel to be converted, then select the Channel Option from the Channel Palette menu, and then select Channel Specific in the Channel Option dialog box.

2. Selected spot color

If the spot color channel is newly created, click on the color sample under Ink Characteristics, and then select the color of the color center meter; if you want to turn an Alpha channel into a spot color channel, click the color sample under Color, and then click Custom , and then select a spot color from the color library, OK. It should be clear that the effect of the spot color sample on the display is not very close to the effect printed on the paper. This is to facilitate the accurate preview of the color on the screen. The color in the color library is the manufacturer's standard color code.

3. Specified spot color hardness (transparency)

In Solidity, enter a smaller value to achieve a transparent, glossy, spot color effect; enter a larger value to achieve an opaque spot color effect, click OK (Solidity option affects only spot colors. Transparency only, no new color will be produced, ie, the hue of the spot color will not be changed.)

Note that after the above work is done, Photoshop displays the colors in the spot color channel in grayscale mode. For example, in a region where ink saturation is 100%, the result is a black display. In order to display the spot color in the channel, from the Preference menu in the File menu, select Display & Cursor and then select Color Channel In Color.

Do you need to hollow out the spot color area on the image?

Many Photoshop images are continuous tone images, so you don't generally need to worry about the missing white. However, when you add spot colors to a Photoshop image, you may need to manually empty the image area. This is because spot color channels are always overprinted on other color channels and may produce unsatisfactory printing effects. For example, suppose you use PANTONE 353 CVC ink color to print pale green text on an image. The text is superimposed on the image, making the overprint area appear ink tone, the text looks dirty and poor readability.

Whether it is necessary to hollow out the spot where the spot color appears in the image depends on the image, the selected spot color, and the desired printing effect. If you don't understand whether the spot colors need to be overprinted in other colors, you may want to ask the responsible printer. Here are some hands-on instructions.

In order not to overprint the spot color area on the image, it is necessary to hollow out the area corresponding to the spot color area on the image. In addition, in order to facilitate accurate overprinting during printing, the area of ​​the hollow part should be slightly shrunk, that is, slightly smaller than the spot color area. If you do not do such a compensation job, as long as there is a little overprinting during printing, then there will be obvious leaks on the edge of the spot color area. The best way is to ask the printer about how to compensate. The printing person usually uses the number of points to represent the size, and in Photoshop it is set by the pixel. The following formula can convert the number of points into the pixel value:

Image resolution (pixels/inch)/72×(points recommended by the printer) = number of pixels for shrink width

1. Loading spot channels into CMYK channels

Select the main channel in the Channel Palette, select Load Selection from the Select menu, select the channel name from the Channel menu, select New Selection, and click OK. Or you can use the shortcut Ctr (Windows) or Command (Mac), and then click on the spot color channel in the Channel Palette.

2. Properly shrink the size of the spot color area

Select the Contract command from the Modify submenu of the Select menu, enter the appropriate contraction value, and click OK.
3. Delete selection

Where the spot color is overprinted, delete the contents of the C, M, Y, and K channels, respectively.

Avoid moiré when using spot color channels

When two different ink colors are overprinted with the same screen angle, moire appears on the final print. If spot colors are overprinted on other colors of the image, measures need to be taken to prevent the occurrence of moiré. Especially when there is more than one spot color channel, pay more attention to this issue. To avoid the appearance of moire, the most critical point is to set the correct web corner in Photoshop, or set it in Adobe PageMaker or Adobe Illustrator.

In Photoshop, select Page Setup from the File menu, click on Screens, uncheck Use Printers Default Screens, select a spot color from the Ink pop-up menu, and enter the appropriate number of screen lines and screen angles. In order to achieve the best printing effect, it is best to consult the printer before setting.

If the production is output in PageMaker 6.5 or Illustrator 8.0, it is also easy to set a new screen corner in these applications. You can set the screen angle in the Print Color dialog box in PageMaker. In Illustrator, set the web corner in the Separation Setup dialog box.