Slashdot Mirror
Rearranging Pixels For Performance
tepes writes "From bottomquark, A new method of sub-pixel rendering could make monitors cheaper to produce. ClairVoyante Laboratories developed the PenTile Matrix, which uses five sub-pixels instead of the typical three, to take advantage of the fact that the human eye is more sensitive to blue colors."
i thought its green..
The human eye is least sensitive to blue. It it most sensitive to green, followed by red then blue. R
As with all slashdot posts, the posting is inaccurate.
The human eye is *least* sensitive to blue... that's what this thing is about, sort of.
It's also not a new method of sub-pixel rendering.. it's a new method of sub-pixel layout.
The theory is that in a conventional LCD, there is too much blue.. it's wasted space, resources, etc.
This thing both changes the color proportion, and the way the thing is wired up. adjacent subpixels of the same color are driven by the same driver.
Briefly...
It is a really well written desription, it is a shame Design Engineering didn't have an writer that could understand it.
The human eye is less sensitive to blue.. That's why blue is often used as a background color, and why yellow (absense of blue) text on a white background is hard to read.
Quote from the article: "The human eye, however, perceives blue at a much lower resolution than red and green."
They're saying blue is the *worst*. Also, I think sensitvity is different than resolution.
Bolding in block quote is mine.
Rearranging the color pixels for color stealing is a reasonable idea, and making blue a little bigger is a nice tweak. Is it worth it? That's difficult to say. Subpixel rendering using color stealing on current LCDs actually does roughly put the extra resolution where you want it for high resolution text--vertical lines are the problem in small text, no horizontal lines.
It's not just you, that's how human vision works in general, and it's exactly the effect this new layout exploits. There are fewer blue pixels (which are therefore further apart) because our spatial perception of blue is less exact than of red/green. In effect, since we can't see the higher resolution of blue, why provide it? Having the same number of blue pixels as red or green is wasting a lot of pixels -- due to the "bluriness" in which we perceive blue, there's no point in having that many blue pixels -- we can't tell the difference between that and only having half as many blue pixels.
"Convictions are more dangerous enemies of truth than lies."
The human eye has two different types of photoreceptors called cones and rods. Cones
come in three variations for color vision.
But they don't perform too well in low light
conditions.
Rods can only perceive green or yellow light
and are much more sensitive.
That's why your color vision is reduced at
night and it's why it's so hard to see blue
stuff in low color conditions.
Why do you think blue isn't picked up by your eyes as well? DUH! WAVELENGTH!
Blue does not focus at the same distance as the other colors, by enough of a margin to make excess blue make images seem fuzzy.
The reason the eye is less sensitive to blue is that there are far fewer blue senstive cones than red or green. These blue cones are actually more sensitive to light than the red or green ones, but their deficit in numbers more that conteracts this.
Additionally most blue cones are outside the fovea (the bit of the eye that has the highest density of colour perception cells) so they are thinly spread, and this spread makes the resolution of the blue image poor.
But even this is not the end of the story - the brain does all sorts of visual image processing tricks and the blue signal seems to be amplified to compensate.
Finally the focus bit - blue has a different focus to red and green in the eye, so the image will always be a bit blurred. This is probably the reason why there are so few cones in the fovea - the image would be blurred anyway and your vision would not improve even if you increased the number of cones.
Checking out the linked page, there are explanatory graphics midway down, but they're simply wrong. They show an enlarged letter A, (black on white) then show how that letter is formed on 'stripe' CRTs vs their tile system. The problem is that they have it reversed. They show the color phosphor dots on the black areas and the white areas are still white. The more fundamental difference here is that CRTs are additive, while LCD displays are subtractive, but they don't even go into that.
Worse, they base their assumptions of superiority on the misconception that striped CRT monitors have one trio of RGB stripes for each pixel. They don't even address the triangular RGB phosphor pattern that non-trinitron CRTs use.
In a nutshell, it sounds like a neat idea, but it's no panacea, and looks like it'll have many of the same edge-color problems that current CRTs do (Trinitron and non), only they'll be more obvious on 45deg angles of red and green surfaces, rather than 90deg angles. Take a look at the tile pattern, and see how the pattern does still have stripes, only they're rotated 45degrees right for green and 45 degrees left for red. I imagine a field of 100% blue will, on close inspection, be a thousand little points of light, since each one is surrounded by dark space that takes up 70% of the screen.
Of course, the proof is in the pudding. I wonder when they'll have samples at tradeshows.
Kevin Fox
What makes column drivers more expensive is that they need to switch with a much higher freqency than the row drivers.
You probably experienced presbyopia, which is the gradual loss of flexibility in your lenses, thus making near items harder to focus on. This is a normal process that occurs with age.
Admittedly, looking at a monitor all day long can cause eyestrain, especially if you tend toward hyperopia (farsightedness) to begin with. That's my problem: While I can see all right at distances of a couple feet from my face and beyond, my eye muscles have to strain constantly, even when I'm focused at infinity, and working on a computer screen all day every day makes the strain get really bad if I'm not wearing my glasses.
"Biped! Good cranial development. Evidently considerable human ancestry."
No it's not. Do a google search on CLEARTYPE to find pages describing the technique that the Apple ][ was using (Woz == God) and that M$ tried to patent twenty years after.
Do another search, and you'll find the pages where Steve Gibson *retracted* that statement. The Apple II didn't have subpixel rendering. It simply used its pixel generator to create colors on top of a black & white NTSC signal by having a high enough resolution that the bandwidth of the signal crossed over into the area reserved for chroma data.
There's a big difference there.
Try reading the actual ClearType papers too -- there's a LOT of engineering behind ClearType, including the use of conceptual 'perfect' display which is down-transformed to match the actual display, and then reverse-transformed to allow tuning to match the conceptual display as much as possible (ie. with a minimum of signal loss). All heavy signal processing stuff.
Simon
Coming soon - pyrogyra