THE TELEVISION PIXEL PAGE 12 images comparing pixel sizes and shapes from many different brands and types of televisions.
There's no doubt about it, we live in a pixilated world. They are everywhere in our televisions, computer monitors, cameras, and even telephones. Yet like the air we breath, even though they are all around us few people have actually seen them. This thought occurred to me when in 2005, my trusty 20-year-old television died and I had to purchase a new one. Front and center on every description I read for likely replacement televisions was some sort of reference to the number of lines of resolution and through implication, a reference to the ubiquitous yet invisible pixel.
This page drags forth the stealthy pixel into the light of easy visual perception. I went to a local electronics store and using a close-up camera, photographed the pixels that made up the images on many different types of televisions. I'm posting them on this page because while there are countless tomes written about them that are easily available on the Internet, repeated searches failed to turn up a single site with pictures of them enlarged enough to see what we are paying for when we purchase a television.
First, a little definition:
The picture on a television is made up of hundreds of horizontal lines. Each of these lines is composed of a row of small, bright dots. These dots are what we call pixels. They are so small that unless you push your nose up against the screen you won't be able to see them. These pixels are linked into groups of three to create what's called a picture element. One pixel in each picture element is red, one is blue, and one is green. At normal viewing distances the pixels are so small they blur together into a single color. By varying the brightness of the colors in a given picture element the overall color can be controlled.
Although the magnified images of pixels that follow appear to be red, green and blue, when viewed from a distance they all appear white, the result of mixing the amount of red, green, and blue in each picture element.
The following is a picture of the pixels on my 20-year-old, low-definition, RCA 24-inch television:
Like the rest of the images on this page, it was taken with a special mask over the end of my camera that had a small square opening and two reference marks 0.10 inches apart. The reference marks enabled me to make sure that all the pictures could be enlarged to the same relative size. These reference marks show up as two vertical lines at the top of each photograph. If your computer monitor is set to 72 dpi, then these reference lines should appear 0.80 inches apart and represent a magnification of 80 power. (Each set of red, green and blue pixels represents one of the picture elements mentioned earlier.)
The first sets I looked at were high definition cathode ray tube (CRT) televisions by Samsung, Toshiba and Philips. They all had a pixel pattern similar to my old set. The following is from a 27 inch high definition Samsung CRT television:
You can easily see that even though the screen on this 27-inch set was slightly larger than my 24-inch set, the pixels are both shorter and narrower, the result of this being a high definition set.
The pixel size for any set is determined by the set's resolution (480 horizontal lines for the old, low resolution standard, either 720 or 1080 for high definition sets) and the size of the television's screen. It's very easy to have a high definition set with pixels that are larger than a low definition set. For example, the pixels on my old set are 0.003 inches wide and 0.011 inches long. The pixels on a 60 inch high definition plasma screen with 720 lines would be approximately 0.004 inches wide and 0.015 inches long, about 33 percent larger. This doesn't significantly effect the appearance of the image because in both cases you sit far enough away so the individual pixels all blur together.
Now let's look at a 32 inch, high definition, 4:3 ratio CRT set by Sony:
Note that instead of clear horizontal breaks between the pixels, they all appear to merge into solid vertical bars. I read that the Sony Trinitron WEGA CRTs are different from all other CRTs because they don't have horizontal grids in the tube's mask. This is supposed to account in part for the excellent image quality many claim for Sonys. Another difference is that the picture elements all line up in even rows, whereas in all other brands, like the Samsung above, the picture elements are offset like concrete blocks in a wall.
Here's what a 34 inch wide screen high definition Sony looks like:
Note that even though this set is larger, the pixel widths are narrower. I suspect that's because this set features 1080 lines of resolution whereas the 32 incher above had only 720 lines.
Next let's look at some plasma sets:
A 42 inch ED plasma:
In plasma sets each pixel is a small gas-filled bubble that's electrically excited to glow. I believe the complex matrix of horizontal black lines are the wires connecting to each bubble.
A 50 inch HD plasma:
Now for some LCD televisions:
A 26 inch high definition LCD:
Liquid Crystal Displays (LCD) work by applying an electric field to a thin layer of a liquid to control the orientation of how its molecules are arranged. One orientation permits light to pass through while another makes it almost opaque. A light behind the LCD panel illuminates it and when some pixels are oriented properly we see the light through them.
LCD technology has two problems: First, some of the backlighting shines through pixels that are supposed to be dark, this reduces the contrast ratio of the set. Plasma and CRT tubes have contrast ratios around 3000 to 1. The best LCDs are limited to 1200 to 1. this limits the amount of detail you can see in dark areas of the screen. Second, the physical nature of the liquid crystals makes it difficult to switch them as fast as is needed to display high action scenes. This is the cause of the image smearing seen when the camera tracks a fast moving object. The picture refreshes every 0.016 second but the pixels take 0.019 to reconfigure. Samsung started releasing LCD sets in November of 2004 which were supposed to have a refresh rate of 0.008 seconds, which should solve this problem.
A 42 inch high definition LCD set:
Note how much larger the pixels are than in the 26 inch LCD unit. This is because both sets have the same total number of pixels so the pixels in the larger set have to be larger to fill the increased area.
Here are three projection sets: (LCD and CRT projection TVs work by using lenses to enlarge and project an image created by a small screen onto a larger screen. DLPs operate slightly different.)
A 50 inch high definition CRT projection TV:
A 60 inch LCD projection TV:
And a 46 inch DLP high definition projection set:
DLP stands for Digital Light Processing. It uses a microchip, similar to what's in your computer, that is made up of millions of tiny motorized mirrors. Red, green and blue lights flash on the chip and the mirrors are signaled to reflect them either toward or away from the screen. Each mirror plays the part of a single pixel.
Finally, let's take a look at the pixels on a 17 inch CRT computer monitor:
As you can easily see, they are a tiny fraction of the size of pixels on televisions. They have to be because unlike televisions, monitors are viewed very closely.
I hope you've enjoyed this page as much as I had putting it together.
If you're interested about the set I finally got to replace the old RCA, it was a Sony 32 inch, 4:3 aspect ratio, high definition CRT. This selection was the result of many factors, not the least being that like many middle-aged people I have hundreds of old VHS tapes and the Sonys are one of the few HD sets on which standard analog and VHS signals still look good.
Three years after posting this page I decided to upgrade my television system to a high definition wide screen LCD. The set I selected was a 52 inch diagonal Samsung 860 LCD set with 1080 by 1960 lines of resolution. Since the old RCA was only a 768 set the new television is a significant improvement. Equipped with a Canon 50D 15.1 megapixel camera and a Canon 5X super macro lens I turned my photographic skills on the new set and got some astounding images.
Again, the two white reference lines are 0.10 inches apart. Note that there are more pixels between the lines than in the previous "high definition" pixel images. That's because back when those images were taken sales people in the stores I took them in wouldn't talk about which high definition the sets were. It turns out they were only 768 sets. Focusing in on just a few pixels brings out even more detail.
Besides the obvious detail that the internal connections only appear in alternating rows of pixels, looking closer shows that the shape of the wires (?) within each pixel also alternates. In the first green pixel in the lower left the wires follow a zigzag path. In the lower right green pixel they follow a simpler course. The image above represents a 150x magnification. As close as I can calculate, each pixel is only 0.007 inches wide. That makes the tiny wires leading from the inner black square to the edge of the pixel less than 0.0001 inches across. The most interesting feature about the above two images can't be seenL: they were both taken of a white screen. While I understand that a wide range of colors can be created by mixing red, green and blue as varying intensities, it's still had to accept that the lightest color, which is white, can be made from three darker colors.
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