Scan lines are more of an illusion.
This is a really bad way to think about this....
Ignoring the fact that if you subscribe to this conclusion, you must also subscribe to the idea that the
entire image is an illusion because it is simply 3 converged beams forming a dot at any one given place on the screen, there is this stuff called phosphor on the inside of the tube that continues to emit light even after the beams have moved away from it. How long it continues to do this is based on the type of phosphor used, which is why the phosphor type is called out as part of the specification for any given tube.
But regardless of that, you have what is called "persistence of vision". Your brain can only process visual imagery so quickly, which is why you can watch a movie with 24 frames per second separated by blackness and see moving imagery without obvious flicker. We can argue all day long about whether something is real because we can only perceive it as such, but the plain fact is that lines are created, and we can see them.
As the beams move horizontally across the screen, and have physical space separating them, there are indeed lines formed by the scanning. Scan lines is a real term and it refers to exactly the thing that you would expect it to refer to; lines created by the scanning method. Even very high frequency displays have them, but they are far less apparent because they are spaced much tighter together.
What is also interesting... is that each R,g and B pixel area... can be lit up fully, or in part. Thus, you see examples where 1/4 th the red pixel dot is lit - while the rest of it is dark.
Again, this is absolutely minimized on a properly adjusted display. If another color is being consistently illuminated when it should not, even partially, you have "color purity" issues.
Interestingly, you would think that the colors should be Red, Yellow, Blue. But the TV uses green instead! Why? When the green is lit to insane levels...it changes appearance to yellow. Red can change to bright orange. Deep dark blue can be very bright light blue. All this without the need for use of 2 colors, as would be needed for painting.
Steve, please stop. You are doing the readers of this board a grave disservice. It's so far off of the mark, I hesitate even to quote it. Mixing light is very different from mixing pigments. With light, the primary colors are red, green and blue. Primary colors from a standard color chart, i.e. reflected colors (frequencies of light neither transmitted nor absorbed) are red, yellow and blue.
With light sources, CRT's, LED's, etc.. you get yellow by mixing red and green. You get orange by mixing less green with the red. Bright blue is achieved by mixing equal parts of red and green with high intensity blue, thereby adding a higher "white" or intensity component.
If you are getting orange from your red gun, it is simply because the gun is no longer properly aligned with the shadow mask, or the gun is so severely out of focus it is creating muddy color by bleeding into the surrounding colors. You are describing the characteristics of a "broken, or maladjusted monitor", not a properly functioning one where these things are much, much more well controlled.
Another thing to consider is how different Dot pitch will make a display look completely different. I believe dot pitch is the size of the r,g,b sections. (or all 3 combined into one) Its very clear when you look at your pc monitor how a small dot pitch changes the look of the output compared to your tube TV. You can not even grasp a hint of a shadowmask... yet it is there, its just amazingly small.
Usually, the dot pitch of a monitor is pretty closely matched to the scanning capabilities of the tube. It would make no sense at all to have a very fine dot pitch on a display that was capable of scanning at only 15.75khz (CGA) as it would be a more expensive component that is never taken advantage of. This is why you see large dot pitches on TV's and Arcade monitors and small dot pitches on PC monitors. As a side note, the dot pitch of a shadow mask is why there is a real raster resolution equivalent to a color vector monitor. As color vector monitors have shadow masks (unlike mono ones, which do not) the vector imagery can be no higher in resolution than the shadow mask allows.
Similarly, there is more than likely a big difference in the low res monitors made at the time of Turbo, than the ones made today. I believe the dot pitch is smaller now.. and they use a form of scaling to make up the difference. Thus, todays new low-res monitors would actually show very visible dark lines where the extra unused pixels were.
The guns themselves may be more accurate.. as well as refined materials and other technology to reduce bleeding and mixing.
Where's the head shaking smiley when you need one
. As a tube and the circuitry ages, all of those important controls become less able to perform their jobs. The phosphor can burn away (screen burn), the filaments in the color guns will corrode and/or use up the coating from which the electrons are created, making for weak output. The capacitors and other components which control timing and geometry start going out of tolerance. The shadow masks can move from being shaken or bumped a little too hard in transportation from one place to another, or warp/move from years and years of being heated and cooled. These are just some of the things a CRT can experience over time.
If you are trying to compare a monitor with 20 years of use with a new one, regardless of the date of manufacture....well, let's just say that whatever conclusions you draw will not have much validity. The dot pitches are not especially smaller today for the same frequency of display, but you will probably be less likely to find the traditional dot triad type of mask.
these games were drawn with the bleeding and mixing in mind.
While this is true, they were
not drawn with a malfunctioning display in mind. In fact, some graphics were so meticulously planned to take advantage of the way CRTs work that anything but a properly functioning display would cause the graphic to turn to "mud", not terribly unlike that representation of the Turbo car you are showing.
RandyT
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Topic: Trick with using PC CRT (Read 4897 times)
