Backward Calibration

Holding the printed copy in your hand, and with the image open in (best) Photoshop or (next best) InDesign (followed by Illustrator, then Quark), adjust the settings on your monitor until the two are as close as you can possibly make them. The more images you can do this with, the better. When in doubt, I open up about ten small images and work on the monitor adjustments while they are all right in front of me. You may find that while most of the color range is reasonably accurate, one area may be more or less saturated than you are happy with. If so, you will need to estimate roughly how much lighter or darker a particular color is, and then you can try recalibrating your monitor.

With any calibration method there is usually a degree of compromise, but that is all we can really hope for. It is just not possible to completely rely on your monitor for accurate color. Fortunately, the kind of mix in a typical continuous-tone image means it is slightly less susceptible to variations in appearance than an area of flat color, where a slight difference can radically affect the result. Fortunately, the flat areas are the easy ones to fix. Therefore, while not being able to completely trust what you see on screen, you can at least calibrate things to the point of being able to trust the mid-tone information that your monitor is showing you, and possibly much more. You cannot use it to visually judge the highlights, or the shadows, and especially not the exact colors—but for the general appearance, and the overall lightness or darkness of the mid-tone range, you can open up an image on screen and know that it is extremely close to how the printed result will look.

I have used backward calibration to get amazingly accurate color output from the print shop without having to trust my monitor 100%. To do the same, you will need a good tint book and a good desktop inkjet printer, or some other way of producing color prints of your work.

If you do not have a reasonably modern inkjet printer—and by reasonably modern I mean one that can produce images at a resolution of at least 720dpi and preferably much higher—then you are missing out on a very useful piece of equipment (see Chapter 7 for more about inkjet resolution). These printers are amazingly cheap, especially in letter size (US) or A4 (UK) formats, and their high-resolution prints, when they are on the right paper, are superb.

The manufacturers of inkjet printers tend to sell them at very slightly more than cost, making them look like an extremely reasonable purchase. Then they truly stick it to you for the ink. I am reliably informed that, weight for weight, inkjet ink is more expensive than gold.

The idea is that you can use the inkjet printer to generate a print you are happy with, then use the tint book and the print to figure out what color specifications you actually need in the image on screen.

For this example, let us say you have designed a book cover. It is all there on your monitor, and it looks great. Then you print it out and you are not quite so happy. So you have to adjust the color and continue to print it out until you have a print of a book cover you will be proud to include in your portfolio. This is the one you are going to show the client as a final design draft.

In order to use a tint book as an aid to the following, you need a good tint book rather than one that shows only colors made up from C, M, and Y—such as many produced by print shops. Instead, try to obtain a copy of the Pantone Process Color Guide (see Chapter 10), which includes tints made from all the CMYK colors.

Print out another copy and cut little holes in it so that you can put it down over the pages in the tint book. Move it around until you find the square that is the closest color match to it, then adjust the tint specifications in the software until they match those shown in the tint book.

This is easy to do when creating images in Adobe Illustrator or CorelDRAW, where you have to decide what color to make everything anyway. It is much harder to achieve using Adobe Photoshop, where you are very often working with continuous-tone images. However, with practice, it can be done—especially if your design allows you to make selections of certain areas and adjust them without disturbing things in the rest of the image. Use the individual channel settings in the Levels and/or Curves windows after placing markers on the image with the Color Picker tool. Then, the Info window can give you before/after information as you make adjustments. If you have previously calibrated your monitor using the method described below, you should easily be able to tell if your image is getting out of hand.

As for the areas that backward calibration cannot reach—the highlights and shadows—these can be calibrated very accurately using the method described in the next chapter.