Creating good prints has always been very important to me. This started in the darkroom where I worked to create as technically perfect black and white images as I could. Sometimes I even under and overexposed 35 mm film so I could over and under develop the film depending upon the conditions. I worked on techniques to create "velvety black feeling" images.
I took this same concern with me when I began to work on the computer. Initially, I had very little to work with. We did not have real profiles for desktop printers. Color management was still in its primitive stages, and to get a print to match a monitor and the monitor to represent a color correctly was not easy. Now, of course, things are very different. But many concepts are still the same. I am going to spend the next few weeks writing a series of articles on various aspects of desktop printing and scanning. They will be quasi-tutorials and will deal with the characteristic of color, image resizing and resampling, some tips on scanning using the Nikon SuperCool Scanner 4000 ED and how best to take pictures for scanning, the questions surrounding archival printing, and possibly some new techniques of printing. Of course, these topics can change and will not necessarily be in the order presented.
I want to start with the basics and the basics all go back to Color. To have control over printing, it helps to understand color. It helps to know the relationship between the colors seen on a monitor and those produced by a printer.
Understanding color on the computer can be a bit tricky since the computer and its peripherals make use of more than one type of color model or color space. This article will address two types of color spaces - additive and subtractive and explain how they interact and function.
Additive colors are the colors that are inherent in light. They are the colors indigenous to monitors, digital cameras, and scanners. The human eye, also, sees these colors. They are red, green, and blue (RGB). They are called primary additive colors because when added together, they form white.
Subtractive colors are those used in the printing trades such as dyes, inks, and pigments. The term color separation should be familiar to most people. These colors are cyan, magenta, and yellow. These colors are called absorbing or subtractive colors since when light is absorbed by all of them, they produce black. These are the colors used in printers. (Although the normal printers made for home use, do not exactly follow this rule. This exception will be commented on briefly at the end of the article.) These colors are commonly referred to as CMY colors. However, usually one sees CMYK. K stands for a truer black since when 100% of C, M, and Y are combined, the resulting color is a muddy dark brown. All of these colors are related. For example:
white = red + green + blue
black = cyan + magenta + yellow
cyan = green + blue
red = yellow + magenta
magenta = blue + red
green = yellow + cyan
yellow = red + green
blue = cyan + magenta
The above list should show an emerging pattern - one of interrelationships. RGB and CMY colors form a complementary relationship.
Thus, if one has an image that contains yellow and one wants to intensify the yellow, one can add more yellow or one can subtract blue. The best way to understand complementary colors is to set up an image and manipulate the individual colors.
The following were created in Adobe Photoshop to demonstrate that the two color spaces are not exactly alike. That is why an image on a monitor does not always look the same when printed. (Other factors are also at work.)
The following illustration shows how RGB colors appear to be different when created in different color spaces.
In the next set of examples, notice how CMY colors vary depending in which color space they were created.
The following examples show how the two color spaces are different. Notice how the maximum amounts of blue and the maximum amounts of red form magenta in RGB color space. When this space is converted to CMY space, the color is not the same as if it were originally created in CMY color space.
The above screen capture is from the Adobe Photoshop 6 Print screen. The Print (Color) Space that is circled in red states "Same As Source". The source can either be "Document Untagged RGB" (green arrow) or "Proof Setup: Photoshop 5 Default CMYK" (blue arrow).
The problem with color perception does not end here, unfortunately. All one needs to do is look at a piece of work under tungsten light, under florescent light, and under daylight. None of the colors will look the same.
If you know the source of light that will be used to view your work, then use that source as your guide. If not, try to use a combination. For instance, daylight florescent lights can be purchased. Or work can be viewed near a window in the middle of the day but under a tungsten lamp. In other words, use a combination of lights. Get to understand how these lights will change the perception of the colors. One can continue that various inks, printers, monitors, papers, etc. all play a part in determining color output. While this is true, one has to stop somewhere. Basically, if one understands colors and how they are related and what makes them change or appear to change, one can work with them with a decent degree of accuracy.
How colors look on my monitor are extremely important to me. As computing has progressed into the gaming and 3D area, the emphasis in video cards has been toward speed, 3D, and animation. Monitors are advertised as being super bright. I have experienced some of these and went through a number this last time I upgraded until I could get ones that had good color reproduction and weren't so bright that I needed sunglasses. Since I concentrate on what I will call non-animation, I use Matrox video cards, the Parhelia for my main machine since I use two monitors. While it is not known for its 3D animation or gaming capabilities, its color representation is excellent and it holds its own in the other areas. I also found that the ViewSonic P95f is an excellent moderate priced monitor. There might be better ones on the market, but it is very hard to test monitors in ones own home and be able to return them if you just don't like them, so that is why I pass on my experience.
I am very often asked what is the best resolution for printing and how can I print this picture that was sent to me over the web. My next article will deal with the two R's -Resizing and Resampling and how they are related.
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