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Dynamic Contrast Matching -- How it works, how to use it, and how to get it.

By Tom Hauenstein

ColorByte has recently announced a new free upgrade for ImagePrint 7.0 users. The main feature of this upgrade is Dynamic Contrast Matching. Dynamic Contrast Matching, or DCM, is a new function within ImagePrint that makes it easy to get the proper contrast and brightness reproduction on every paper.

Basically, the software analyzes the printer profile and color gamut of a certain paper, printer, and ink combination, and by using this data a curve specific to the dynamic range of the paper is automatically generated, resulting in perfect tonality from print to print.

How it Works

Not all papers have the same color gamut. Most luster or glossy photo papers have a deep color gamut, which enables them to produce great detail in the shadow areas. Many fine art papers and canvases, on the other hand, have a shallow color gamut, so there’s not a lot of room for three-quarter tones and shadow areas.

Figure 1 shows the color gamut differences between canvas (the opaque gamut rendering) and a luster photo paper (the translucent gamut rendering, which overlaps the gamut space of the canvas). As a result of this color gamut differential, the three-quarter tones and shadow areas print as nearly identical colors on canvas and fine-art papers so you tend to lose all detail in those areas. This is commonly referred to as blocked-up shadows.

DCM redefines the midpoint of the image to the middle of the color gamut of the paper, printer, and ink combination. Figure 2 shows the color gamut of the canvas. The line in the image represents where the midtones are printed through a traditional printer driver, or ImagePrint with DCM turned off. As you can see, there is a lot more gamut above the midtones line than there is below.

When you turn DCM on, the midtone line moves to the middle of the gamut with the use of a curve adjustment (see Figure 3). This should leave the same amount of gamut above and below the midtone line so that there is more room for shadow detail. This will eliminate blocked up shadows and return the shadow detail in the original image.

How to use DCM

First, you will have to run the update to ImagePrint 7.0.3. Then you will have to download new profiles that allow you to use DCM, which you can do using Profile Manger (click here to download this utility). With the Profile Manager you will see new sections under the printer labeled with DCM (see Figure 4). Once you load the new Gray profiles you will be able to utilize the DCM features of ImagePrint.

You will see a new option in the Color Management section of ImagePrint. Go to the Black/White Controls tab. Click on the DCM check box and it will automatically adjust your print (see Figure 5). You will be able to see the adjustment in the ImagePrint preview. Check the box on and off to see the effect it has on your black and white images.

Figure 6 shows an image conglomeration with DCM turned off.

In Figure 7 I turned the DCM on and left the slider at 0. You can see the difference immediately. Note that the gray step at the top of the image is more balanced.

The slider at the bottom allows you to adjust for low-key images and high-key images. Moving it left toward the negative side creates more detail in the low-key images (see Figure 8), while moving the slider right to the positive side brings more detail in the high-key images.

How to Get DCM

In order to be eligible for the 7.0.3 upgrade you must already be on version 7.0 of ImagePrint. If you are not, call your LexJet account specialist and they will get you a quote on how much it will be to do so. It’s about 35 percent of the retail price of your current version to upgrade.

If you are already on 7.0 and want the free download, go here. Click on Version 7.0.3 Update, then select the updater for PC or Mac and run it. It will install automatically and you’ll be ready to go.