Ask Designorati is a new feature at Designorati.com devoted to answering readers’ questions. If you have a question about Photoshop or Photoshop-related software and techniques, [1] click here to ask your question and stay tuned for a response!

I received this question a couple weeks ago:

ABOUT HEXACHROME

Hexachrome is a relatively new print invention, having been created by [2] Pantone in 1994 to improve upon conventional CMYK printing. Any print designer can tell you that combinations of cyan, magenta, yellow and black ink can be inadequate when reproducing certain colors, such as fluorescent colors, picture-perfect fleshtones and vibrant blues. The four inks in general are not very pure, and the cyan in particular is a dirty color. Pantone responded by creating a six-channel color model (which is supported by most commercial printers, who often have six-unit presses) that uses purer CMYK inks and adds Hexachrome Green and Hexachrome Orange inks to accommodate shortcomings in those color ranges. The result is an image that is more vibrant and has a color gamut approaching that of the RGB color model, and it is used best in circumstances where vibrant RGB color needs to be preserved in an ink-based printing. [3] Click here for a gallery of brochures and designs printed using Hexachrome technology.

For a good article about Hexachrome by Dan Reid, [4] click here. It’s reprinted from the August 2005 issue of [5] Digital Output and hosted on [6] Pantone’s website.

A Hexachrome image in the computer is not much different than a CMYK image. CMYK images have four channels (cyan, magental, yellow and black) while true Hexachrome images have six:

• Hexachrome Cyan
• Hexachrome Magenta
• Hexachrome Yellow
• Hexachrome Black
• Hexachrome Green
• Hexachrome Orange

All six of the Hexachrome inks can be found in the Pantone Solid Coated or Pantone Solid Matte color libraries.

MAKE HEXACHROMES WITH OFF-THE-SHELF SOFTWARE

There are two ways to create Hexachrome images: conversion with off-the-shelf software or creation of six-channel images in Adobe Photoshop and other graphics applications that support spot color and multichannel images (Illustrator does not). Of these two, using conversion software is the best bet since it can reseparate existing channels in order to keep consistent color but take full advantage of the new inks.

Pantone produces [7] HexWare, currently on version 2.5.2. This $899 software allows Photoshop and Illustrator to convert RGB and CMYK images into Hexachrome images. For $100 more you can go for the [8] ColorSuite with Hexachrome, which includes HexWare, Pantone Solid in Hexachrome Guide, Pantone Color Bridge, Hexachrome test form and test form CD.

MAKE HEXACHROMES, DO-IT-YOURSELF STYLE

Given that Hexachrome images are merely CMYK images with a couple extra channels, it’s relatively easy to take a conventional CMYK image and print with the Hexachrome equivalents. The resulting print will show the added vibrancy of the ink but won’t take advantage of the green and orange channels and may not create the color you’re expecting. With Photoshop, you can convert a CMYK image into a multichannel image, add the orange and green channels and achieve a Hexachrome image on the fly:

Step 1: Open your CMYK image (seen in Figure 1; if your image is in RGB color mode, convert it to CMYK by selecting Image –> Mode –> CMYK Color).

Figure 1: The original RGB image.

Step 2: Choose Select –> Color Range… and with the Eyedropper tool select a vivid orange color within the image. Set Fuzziness at 100 to select most of the orange color. Click OK to select.

Step 3: Cut (Cmd-X/Ctrl-X) and paste (Cmd-V/Ctrl-V) the pixels into a new document.

Figure 2: Left to right: the incomplete CMYK image, the orange pixels, the green pixels.

Step 4: Repeat Steps 2 and 3, this time selecting vivid green color, cutting and pasting it into a new document. Figure 2 shows my incomplete CMYK image, plus the orange and green pixels in their own documents. Set these two documents aside for a moment, as they will be the basis for your green and orange channels later on.

Step 5: Convert your first CMYK image into a Multichannel image by selecting Image –> Mode –> Multichannel. The CMYK channels remain as they were. You’ll probably see a color shift take place; I’m not sure why this happens, but I think it has to do with color management within Photoshop. The four channels retain their values, but the color Photoshop displays changes after the switch to Multichannel.

Step 6: Double-click the Cyan channel to display the Spot Channel Options dialog box. In the Ink Characteristics area, click the Color well to get the Color Picker. Go to the Pantone Solid Coated or Pantone Solid Matte color library (click the Color Libraries button if necessary) and find the Pantone Hexachrome Cyan C color (drag the color slider to the very top of the range and click the down arrow three times to see the Hexachrome inks). Click OK in both open dialog boxes to confirm the change from process cyan to Hexachrome Cyan ink. You’ll notice that the ink is stronger and more vibrant.

Step 7: Repeat Step 3 for the magenta, yellow and black channels.

Step 8: Select “New Spot Channel…” in the Channels palette’s flyout menu. In the Spot Channel Options dialog box, click the Color well as in Step 3 and select Pantone Hexachrome Green C. Leave Solidity at zero percent.

Step 9: Repeat Step 5, this time selecting Pantone Hexachrome Green C.

Now we have our six channels, though only four carry color. It’s time to bring back the greens and oranges from the original source: the greens and oranges we extracted from our original CMYK image!

Step 10: Copy (Cmd-C/Ctrl-C) and paste the green pixels from the document created in Step 4 to the Hexachrome Green channel in the multichannel image.

Step 11: Repeat Step 10, this time pasting the orange pixels from the document created in Step 3 and into the Hexachrome Orange channel in the Multichannel image.

Not bad, but our greens and oranges are literally a pale comparison with our original RGB source! Why? Because the Color Range selection didn’t capture every pixel completely in those areas—it’s the nature of that tool to select some pixels only partially, depending on the chosen color and Fuzziness setting. You can fiddle with those controls in Steps 2 and 4, but I prefer using Curves to “reseparate” the channels, modifying them so they more accurately match the RGB original.

Step 12: Use the Curves (and Levels, or any other image adjustment tools) to darken or lighten pixels in the various channels. The settings you use will depend on the image, but the goal is achieve the same colors with a combination of six channels that you had with four. Usually this involves a major bump in the orange and green channels (we are using Hexachrome to gain maximum leverage on those colors, after all) and a slight contrast increase in the other channels. My moves in this instance, all executed with Curves:

• Hexachrome Cyan: 22/11, 80/87
• Hexachrome Magenta: 53/45
• Hexachrome Yellow: No change
• Hexachrome Black: 38/20, 82/87
• Hexachrome Orange: 45/100
• Hexachrome Green: 55/100

Figure 3: The finished Hexachrome image. Look at the greens and oranges!

Figure 3 shows the final result; the original RGB image is below it. You’ll see that I improved the vibrancy of the oranges and greens!

HEXACHROME AND OUTPUT

Multichannel images such as this one can only be saved in five Photoshop file formats:

• Photoshop .psd
• Large Document Format
• Photoshop 2.0
• Photoshop Raw
• Photoshop DCS 2.0

Save your file as a Photoshop DCS 2.0 file and InDesign and Quark will be able to place it in a layout and output separations appropriately (for an easy overview of seps in InDesign, use the Separations Preview). PostScript-based file formats, such as PDF and EPS, can also carry spot color information such as this, but Photoshop doesn’t seem to allow Multichannel images to be saved in these formats.