Digital Darkroom

The Digital Darkroom
Using The Info Tool To Create Better Prints

Darryl C. Nicholas | Mar 1, 2003

Photographic Color Wheel. Opposite colors (red/cyan, green/magenta, blue/yellow) have a tetter-totter relationship--increase one and the other decreases.

In color photography there are six photographic colors (red, green, blue, cyan, magenta, and yellow) plus density and contrast. In order to look at a print and correctly identify what might be wrong with the color balance it is necessary to learn what those six photographic colors look like so you will know them when you see them.

In wet color darkrooms we have an electronic instrument called a color densitometer that will examine a color and tell us, in numerical terms, what the color is. There is a similar tool that can be used in digital imaging to help us to know exactly what color we are dealing with. The tool is found in Adobe's Photoshop. It is called the Info tool.

Notice that all three RGB numbers are almost identical. This is a near-neutral shade of light gray.

No matter how well your system is calibrated, you will not always get from your printer what you think you see on the monitor. The reason is complicated, but the short explanation is that what you see on the monitor is color from glowing phosphors while what you see in the finished print is color by reflected light. The act of calibration is the act of trying to get those two different mediums to match as closely as possible. But even when calibrating is done very well, there remains some large problems that show up when you try to do critical color work. This is where the Info tool comes into play.

Getting Info From The Info Tool
I use the Info tool for three things. First, I use it to tell me if a color that is supposed to be neutral gray is really neutral. Second, I use the Info tool to tell me if something in my picture that is supposed to be solid black will really print solid black or will it simply be a dark shade of gray. If the things that are supposed to be solid black (D-max) in the print really are, then the chances are that the rest of the image will have the proper contrast and density level. And third, I use the Info tool to tell me if something in my picture that is supposed to be a delicate, almost solid white, highlight is really that. If that delicate highlight is too light (washed out) or too dark, then the rest of the picture will not be correct either.

This is an ideal reading for a D-min area of your picture.

What It Measures
The Info tool measures what is in the electronic file, not what you are seeing on the monitor. There are many characteristics of the image that will barely, if at all, show up on the monitor, but will readily show up in an ink jet print. Think of an ink jet print as being a much more accurate and critical representation of the electronic file than the image on the monitor.

For example, the shadows in your picture may appear solid black on the monitor, but print as a dark shade of gray. Further, the contrast of the image that appears on the monitor may appear perfectly acceptable, but the contrast of the ink jet print can appear a little too high. The color balance for the image on the monitor can appear perfectly acceptable, while in the ink jet print, you may see a decided color cast.

This is an ideal reading for a D-max area of your picture.

Assuming that you have properly calibrated your computer system, the next step is to adjust the color, density, and contrast of your image until you have what you want on the monitor. At that point, and before you send the electronic file to the ink jet printer, get the Info tool and check three things:

Setting D-max
The first is to check that the area of the picture that is supposed to be solid black (D-max) really is. The Info tool produces numerical readings for Red, Green, and Blue (RGB). If a color is solid black, the Info tool will read 0, 0, 0 for RGB. However, if it does, then your ink jet printer will not only print that area as D-max, it will also print a lot of other tone values as too dark. That's right, 0, 0, 0 in the D-Max area will cause everything else in the picture to appear darker than it needs to be. So, I always adjust my D-max to read about 10-12 units with the Info tool. That is, D-max should read 10, 10, 10, not 0, 0, 0. If your image's D-max area reads 10, 10, 10 with the Info tool, that area will print as solid black on all ink jet printers, and it will allow other areas of your picture to have more visible details in what would otherwise be excessively dark shadows.

Info tool.

Setting Color Balance
Next check the color balance of your picture by placing the Info tool in an area that is supposed to be a neutral shade of medium gray. If the area is truly medium gray in the electronic file, then the Info tool will read something like 100, 100, 100. Or if the tone value is darker in density, then the Info tool might read something like, 50, 50, 50. In any event, all three numbers will be almost identical if the area is truly neutral. If one of the three numbers is noticeably larger or smaller than the other two, then there is a color cast in that area, and if that area is supposed to be neutral, you can be sure that the same color cast will appear throughout your picture when it is printed.

Checking Highlights
Then, check the delicate highlights or the density-minimum (D-min). Place the Info tool in an area where there should be just a very subtle trace of tone value. In other words, almost, but not quite, solid white. If the area reads something like 245, 245, 245, then it will print with just a trace of tone value in that area. However, if it reads 255, 255, 255 it will contain no tone value at all. If large areas of your picture read 255, 255, 255, they will appear to be washed out in the picture. Even objects that are supposed to be white, like a white building, a white sheet, or a white dress should contain some trace amount of tone value.

Making Changes
You can open the color balance tool and/or the brightness/contrast tool while you have the Info tool in use. That allows you to make a small change and immediately check the results with the Info tool before committing to the change that you have made.
This image shows the picture before I adjusted it using the Info tool, and the next one shows the results of using the Info tool.

Darryl Nicholas has a CD-ROM that he normally sells on his web site for $19.95. It instructs on how to perform a color calibration on your PC computer system with your Epson ink jet printer using only the tools found in Adobe's Photoshop. Write him care of the magazine, and he'll tell you how "Shutterbug" readers can get the CD-ROM for only $3.00. Write to him care of editorial@shutterbug.net.