Adding spot colors (Photoshop)

Adding spot colors (Photoshop)

Spot colors are special premixed inks used instead of or in addition to the process color

(CMYK) inks Each spot color requires its own plate on the press (Because a varnish requires a separate plate it is considered a spot color too.) For information on printing spot color plates see "Printing color separations on section 483

If you are planning to print an image with spot colors you need to create spot channels to store the colors. To export spot channels save the file in DCS 2.0 format or PDF (See

"Saving files in Photoshop EPS format (Photoshop) on section 448

Note: ImageReady supports Photoshop spot color channels as alpha channels.

About spot colors

Note the following when working with spot colors:

For spot color graphics that have crisp edges and knock out the underlying image, consider creating the additional artwork in a page-layout or illustration application.

To apply spot color as a tint throughout an image convert the image to Duotone mode and apply the spot color to one of the duotone plates. You can use up to four spot colors one per plate (See "Printing color separations on section 483

The names of the spot colors print on the separations.

Spot colors are overprinted on top of the fully composited image Each spot color is overprinted in the order it appears in the Channels palette.

You cannot move spot colors above a default channel in the Channels palette except in

Multichannel mode.

Spot colors cannot be applied to individual layers.

Printing an image with a spot color channel to a composite color printer will print the spot color at an opacity indicated by the solidity setting.

You can merge spot channels with color channels splitting the spot color into its color channel components.

Creating spot channels

You can create a new spot channel or convert an existing alpha channel to a spot channel.

To create a new spot channel:

Choose Window > Channels to display the Channels palette.

To fill a selected area with a spot color make or load a selection.

Do one of the following to create a channel:

Ctrl-click ( Windows) or Command-click (Mac OS) the New Channel button in the

Channels palette.

Choose New Spot Channel from the Channels palette menu.

If you made a selection that area is filled with the currently specified spot color.

Click the color box and choose a color (See "Using the Adobe Color Picker on section 261

If you select a custom color your print service provider can more easily provide the proper ink to reproduce the image For more information see "Choosing custom colors

(Photoshop) on section 263

For Solidity enter a value between 0% and 100%.

This option lets you simulate on-screen the solidity of the printed spot color A value of

100% simulates an ink that completely covers the inks beneath (such as a metallic ink);

0% simulates a transparent ink that completely reveals the inks beneath (such as a clear varnish). You can also use this option to see where an otherwise transparent spot color

(such as a varnish) will appear.

Note: The Solidity and color choice options affect only the on-screen preview and the composite print. They have no effect on the printed separations.

To enter a name for the spot channel choose a custom color in step 4 and the channel automatically takes the name of that color.

Be sure to name spot colors so they'll be recognized by other applications reading your file Otherwise the file might not print.

To convert an alpha channel to a spot channel:

Do one of the following:

Double-click the alpha channel thumbnail in the Channels palette.

Select the alpha channel in the Channels palette and choose Channel Options from the palette menu.

If needed rename the channel.

Select Spot Color.

Click the color box choose a color in the Color Picker dialog box and click OK.

(See "Using the Adobe Color Picker on section 261

Click OK. The areas of the channel containing grayscale values are converted to spot color.

Choose Image > Adjustments > Invert to apply the color to the selected area of the channel.

Modifying spot channels

You can edit a spot channel to add or remove color in it change a spot channel s color or on-screen color solidity and merge a spot channel with the image s color channels.

For information on rearranging duplicating or deleting spot channels see "Managing channels (Photoshop) on section 268

To edit a spot channel:

Select the spot channel in the Channels palette.

Use a painting or editing tool to paint in the image Paint with black to add more spot color at 100% opacity paint with gray to add spot color with lower opacity.

Note: Unlike the Solidity option in the Spot Channel Options dialog box, the Opacity option in the painting or editing tool s options determines the actual density of ink used in the printed output.

To change a spot channel's options:

Do one of the following:

Double-click the spot channel thumbnail in the Channels palette.

Select the spot channel in the Channels palette and choose Channel Options from the palette menu.

Click the color box and choose a color (See "Using the Adobe Color Picker on section 261

By selecting a custom color your print service can more easily provide the proper ink to reproduce the image For more information see "Choosing custom colors (Photoshop)" on section 263

For Solidity enter a value between 0% and 100%.

This option lets you simulate on-screen the solidity of the printed spot color A value of

100% simulates an ink that completely covers the inks beneath (such as a metallic ink);

0% simulates a transparent ink that completely reveals the inks beneath (such as a clear varnish). You can also use this option to see where an otherwise transparent spot color

(such as a varnish) will appear.

Note: The Solidity and color choice options affect only the on-screen preview and the composite print. They have no effect on the printed separations.

To merge spot channels:

Select the spot channel in the Channels palette.

Choose Merge Spot Channel from the palette menu.

The spot color is converted to and merged with the color channels. The spot channel is deleted from the palette.

Merging spot channels flattens layered images. The merged composite reflects the preview spot color information including the Solidity settings For example a spot channel with a solidity of 50% will produce different merged results than the same channel with a solidity of 100%.

In addition the resulting merged spot channels usually don t reproduce the same colors as the original spot channels because CMYK inks can t represent the range of colors available from spot color inks.

Adjusting overlapping spot colors

To prevent overlapping spot colors from either printing over or knocking out the under- lying spot color remove one of the spot colors where they overlap.

Use a printed sample of the overprinted inks to adjust your screen display to help you predict how colors will look when printed.

Note: In some cases such as varnish and bump plates you may want colors to overprint.

To adjust overlapping spot colors:

In the Channels palette select the spot channel with the color you want to print.

Choose Select > Load Selection.

To quickly select an image in a channel hold down Ctrl ( Windows) or Command

(Mac OS) and click the channel in the Channels palette.

For Channel choose the spot channel from step 1 and click OK.

To create a trap when knocking out the underlying color choose Select > Modify > Expand or Contract depending on whether the overlapping spot color is darker or lighter than the spot color beneath it For more information on trapping see "Creating color traps on section 479

In the Channels palette select the underlying spot channel that contains areas you want to knock out Press Backspace ( Windows) or Delete (Mac OS).

This method can be used to knock out areas from any channels under a spot color, such as the CMYK channels.

If a spot color in one channel overlaps more than one other spot color repeat this process for each channel that contains areas you want removed.