The subject at writer’s group this month was color and I wrote this for that. Sadly, it doesn’t answer the questions, “What is the meaning of life.”
During one Sunday morning service a pastor was sitting on the chancel steps talking with the children about color. She asked, “What is your favorite color?” Answers were everywhere from blue to red and back. One girl said “Rainbow!” The point the pastor was trying to make was lost in laughter and smiles and the kids quickly set off to Sunday school.
Color is really a matter of perception and cultural meanings. As a physical phenomena, color is just a specific frequency of electromagnetic radiation that human eyes can see. Electromagnetic radiation includes everything from electricity, radio waves, visible light, x-rays to gamma rays. Its basic paradox is that it can either act as a particle or a wave or sometimes both. Yeah, I never really understood that.
Growing up we learn about colors. Most of you were likely taught about the primary colors and the color wheel. Blue, red and yellow. Combine these and you can make all the other colors.
Which naturally leads us to the philosophic question, “Are white or black colors?” The answer is the natural response to all deep questions, “Depends …” In the simplest case think of white as all colors at once and black as the absence of color.
Not everyone can see color. My father was color blind. He was red-green color blind, which is the most common form of color blindness. Red and green looked mostly black to him. This condition is why he only bought black socks. For his whole life, he only owned black socks. Turns out his favorite color was yellow, not because he liked it, but it was the only color he could see well. When our family played board games, dad always was given the yellow marker. He liked to play solitaire, but all the cards looked black so he had to learn that hearts and diamonds were red.
It was also why we didn’t have a color TV in our house. Father saw no point in paying for a color set. We finally get a color TV in the mid 70’s when he wanted one of the big 26 inch screens and found that no one sold a black and white version of that.
Shortly after getting the color TV I enrolled in technical college and starting studying electronics. I thought it would be great to learn how TVs worked. Turns out to be one of those, very simple concepts, but very hard to implement. Basically you have an electron beam pointing at a phosphorescent screen to get a dot of light. You vary the strength of the beam to make the dot brighter or lighter and then by using magnets you can move the beam around the screen. If you wanted color, you’d add two more beams to get three. Each beam would be pointed at different colors of phosphorescent material which you let you have red, green or blue dots very close to each other. To get a white dot you turn all the beams on max and to get black you turn all the beams off. To get red, you just turn the red beam on and the other two off. Getting any particular color, say a nice teal or orange was just a matter of mixing the intensity of the primary colors of red, green and blue.
I hear you saying, “Wait, didn’t you say that the primary colors were, red, blue and yellow?” Yes I did, but that was for pigments, not light beams. Colors you see from using your crayons is really reflected light, that is a white light source shines on your red paper and absorbs all the colors except red which is then reflected back to your eyes. This is a subtractive process, as in you remove the colors you don’t want, to reflect the color you do want.
Which is the opposite of a TV, which is an additive process where black is turning off the light beams and to get various colors you turn light beams on in varying intensities to get the color you want.
I learned all this at one of my first jobs in electronics when I went to work for a company making memory storage and CRT (cathode ray tube) displays for the first generation of medical CT scanners in the early 80’s. These were big machines for the time and one of our memory systems had about four megabytes of memory or about 1000th the memory of the average cell phone in your pocket. The systems we shipped were about the size of your average washing machine. The entire CT scanner often took up most of the basement of you average hospital.
At the time this company was a leader in the market and decided to expand by adding a color printer to the product line. This is when I started to learn about the differences between additive and subtractive colors.
Turns out our grade school teacher wasn’t exactly correct about primary pigment colors. The blue, red and yellow we were taught are actually cyan, magenta, yellow and black. Graphic artists know this as the CMYK system. You can’t really make black with the three primary colors, so our printer had to have black ribbon. White is supplied by the paper and created by not printing on it.
My job was to help the engineering team set up, test and adjust both CRTs and printers so that the two devices would display or print an image that looked the same. We’d get an image displayed on the CRT and we’d try to adjust the printer to get the same shade of red or blue or pink. Let me tell you that adjusting a 1980’s CRT was no joy, there were potentiometers, adjustable capacitors, moving magnets and high voltages, up to 25KV inside the set. Since it was a color set, there were three of everything. It could take a skilled technician three to four hours to get one CRT adjusted correctly while avoiding touching any high voltage sources.
At the time color on CRTs and TVs was controlled by the NTSC standards. That is an acronym for, “National TV Standards Committee,” that was tasked with setting industry standards for transmitting and receiving TV signals. In the lab we referred to NTSC as, “Not the same color.” TVs of the era were notoriously difficult to adjust to get the correct color. I doubt we had two CRTs in the lab that had the same shade of red, pink or any other color.
The brilliant engineer who designed our printer used a dot matrix printer where each color had its own ribbon. The resulting machine was the size of workbench and had four print heads. It took four passes of the print head assembly to create just one line of picture and sounded a bit like machine gun as it ran.
Just like the CRT, these printers had their problems in getting them to work correctly. They were a mechanical nightmare to adjust – each printhead had to hit the paper within one thousandth of an inch of each other while moving at high speed across the platen. The platen, that thing behind the paper, was often curved instead of straight and I can’t remember how many we’d have to go through to find parts that met the incredible tight tolerances the machine required. In addition to a dizzying array of screws, bolts and shims needed to adjust the thing, there was an equally large number of electronic controls to adjust. The fastest I ever got at getting one working right is about a week. And that’s before I mention all the problems we had with the ink ribbons – ink lots not the same, they wore out too fast, and if you used a new red with an old cyan, your colors would be off, even when the machine was properly adjusted.
After a solid year of work it was determined that this wasn’t suitable as a CT image printer. Instead, we tried selling the printer to the military. They took 20 to test and promptly rejected every printer. The company went broke and I eventually went into industrial automation systems and never worked on another printer.
Andrew's View of the Week 