Talk:Subpixel rendering

message: Apple II really has the subpixel rendering. We agree that the color pixel effectively consumes 2 horizontal pixels in the monocrome unit. In the mono unit we have 280 horizontal points. The point is that, we can emulate 280 * 2 horizontal pixels. In this sense, the statement above by Woz and the claim by Gibson is totally irrelevant. (They mean 280 monocrome pixels are subpixel rendering of 140 color pixels.)
To see this, let us concentrate on the monocrome mode, i.e. using mono CRT monitor. Apple II's normal HGR (High-Res graphic) mode has 280 horizontal points. Let compare two commands.
:HGR: HCOLOR=3: HPLOT 0,0: HPLOT 0,1
versus
:HGR: HCOLOR=3: HPLOT 0,0: HCOLOR=7: HPLOT 0,1
The first one looks like a vertical line, but the second looks like a tilted line. In effect, we have only 1/2 unit shift, even in the mono unit!. If you draw a line in this way, we can make use of 280*2 = 560 horizontal points.
This technique is described in, for example Beagle Bros' tip #5. See , page 19. 
This subpixel method is used in rounding some fonts (of course meaningful in the mono monitors) in various games.
Ugha (talk) 02:21, 12 February 2008 (UTC)
replies: text: The flag bit in each byte affects color by shifting pixels half a pixel-width to the right. This half-pixel shift was exploited by some graphics software, such as HRCG (High-Resolution Character Generator), an Apple utility that displayed text using the high-resolution graphics mode, to smooth diagonals. (Many Apple II users had monochrome displays, or turned down the saturation on their color displays when running software that expected a monochrome display, so this technique was useful.) Although it did not provide a way to address subpixels individually, it did allow positioning of pixels at fractional pixel locations and can thus be considered a form of subpixel rendering. However, this technique is not related to LCD subpixel rendering as described in this article.
This is what I mean, and really realize fractional pixel positions. Anyway the last statement depends. In the sense we cannot completely control all the subpixels, this was not successful as LCD subpix rendering, but at least this was the primitive forms of subpix rendering. Ugha (talk) 15:08, 13 February 2008 (UTC)
thread_title: A different claim

message: Could someone add some samples at 1:1 resolution for common LCD colour orders?  It's be nice to be able to compare different techniques' output. --njh 08:47, 31 May 2006 (UTC)
replies: text: Agreed --Crashie 15:18, 22 March 2007 (UTC)
thread_title:  Some samples would be nice 

message: Just wondering if it wouldn't make for sense to resize the first picture. At full size it shows pixel images blown up by a factor of 6. I think it would make more sense to reduce the thumbnail image also by a factor of 6 to render the blown up pixels as 1:1 and prevent strange artifacts being introduced. —The preceding unsigned comment was added by 82.10.133.130 (talk • contribs) 09:33, 17 August 2006  (UTC)
:I think that particular image needs to be introduced as a thumbnail. It is a much better demonstration at its full size. Perhaps it would be better broken into three small (1:1) images and used later in the document, but what I think we should definitely do is choose a new picture to go at the top. The first image in the document should be a simple picture of subpixel rendering, not an explanation of it. Rainwarrior 18:50, 17 August 2006 (UTC)
replies: text: Agreeing with this eight years on. Opening the article with an image where the caption explains that it "does not show the technique" isn't very helpful to the reader. --McGeddon (talk) 17:10, 26 March 2014 (UTC)
thread_title:  Image (re-)size query

message: All the examples assume that LCD sub-pixels are rectangular, making a square pixel. But this isn't always the case - I've just noticed that my two seemingly identical monitors are different - one has the standard pattern, the other has chevron shaped subpixels (a bit like this: >>>) I don't think there's much effect on sub-pixel rendering as they're both based on a square, but it does explain why one always looks slightly more focused than the other.Elliot100 13:34, 14 September 2006 (UTC)
thread_title:  Non rectangular sub-pixels 

message: There are a few ways in which subpixel rendering can be used on existing graphic formats:
* Vector graphics naturally can be rendered in subpixels
* Bitmap-scaling algorithms can be made to use it
* A bitmap can be created in the first place optimised to a particular subpixel layout
But are there any graphic formats out there that are specially designed to support subpixel rendering?  This might improve the rendering quality of certain kinds of images, if the same graphic file can be rendered in terms of the subpixel layout of each device it is rendered on (or in the lack of a discernable subpixel layout, plain pixel rendering).  (For that matter, does JPEG already make this possible to any real extent?)
-- Smjg 12:40, 10 April 2007 (UTC)
thread_title:  Graphic formats 

message: I don't think so.  That doesn't sound quite right.
217.229.210.187 18:52, 4 August 2007 (UTC)
thread_title:  IBM invented subpixel rendering? 

message: An ideal LCD would have a very small "blurring" optical filter on top of each pixel, such that the pixel looks uniformly white, rather than having 3 vertical coloured stripes. This does actually seem to be the case: I observed the LCD on my laptop (Thinkpad T60p) through a strong zoom lens (300mm macro lens, with x2 converter, OM2 camera, very small depth-of-field), and saw the following:
* Focus on surface of screen: white square pixels, with black borders. (screen door effect)
* Focus slightly (50um perhaps) deeper: pixels comprise 3 vertical bars of colour.
* Still deeper: white squares, but with more pronounced screen-door effect.
So, it seems that this LCD, at least, has a small optical blurring filter applied in front of it, to improve the quality. [That would also be why the human eye can't see the coloured sub-pixels, even though a 100um wide feature should be visible to those with good vision]
In such an LCD, sub-pixel rendering makes the image much worse; the effect is colour-fringing around each letter.
Can anyone confirm or explain this? RichardNeill 02:35, 14 September 2007 (UTC)
thread_title:  Sub-pixel rendering makes it *worse* on some LCDs? 

message: ClearType was not an implementation of the IBM invention, which nobody knew about until it was dug up after ClearType came out.  When did Apple's version come out?  After Microsoft?  The original invention by a couple programmers in e-Books was clever but somewhat ad hoc, similar to what Gibson came up with, but with some attempt to filter.  Then the problem was analyzed in MS Research, where it was demonstrated that in fact the method could be used on arbitrary image rendering (MS only uses it for fonts).  The problem was then turned over to John Platt, an expert on signal processing and filter design, who created a much improved version that uses a specially designed FIR filter. 24.16.92.48 (talk) 14:11, 15 July 2008 (UTC)
thread_title:  History and Practice 

message: Note that FreeType with the subpixel rendering functionality shown 
 in these examples cannot be distributed in the United States due to
 the patents  mentioned above.
It can now. The patents expired in May 2010.
:You could have removed that just as easily as I did. Please remember to sign your posts by typing four tildes. Kendall-K1 (talk) 15:45, 3 March 2012 (UTC)
thread_title:  Patent Issues 

message: The article's lede says that subpixel rendering is for LCD and OLED devices—among other devices with fixed subpixels, plasma displays have them (at least according to the Wikipedia article). Someone posted a question on Talk:ClearType about printers. Anyone know if subpixel rendering has been used on any hard output devices? Bongomatic 05:35, 4 December 2011 (UTC)
thread_title:  Non-LCD devices 

message: I added colour as a visual aid to better convey the subtle matrix differences (feedback welcome per WP:COLOUR) - note white on black background was too invasive, and yellow and cyan are better as background due to contrast. I let this bold change bake a bit on PenTile matrix family, RGB (rejected), Quattron already. As this is a bold edit, please discuss. 
As I was there I fixed unrelated issues (overlinking, links, etc) with this edit. The pair of images in the first section "background" is confusing without further explanation i.e. why an article only about additive colours has a subtractive colour example? why "RGB" is coloured with CMY? why when adding the colours we get black? I'm guessing it is meant to demonstrate an LCD with filters?, hence all the black pixels? That is not stated, is out of context, and in my opinion only confuses at that point in the article. Anyone want to remove or fix? Widefox; talk 12:42, 24 October 2012 (UTC)
thread_title:  Colour 

message: Nothing of what I know about display technology leads me to agree that an RGBW subpixel structure would have better colour reproduction than anything, let alone CMYK. (This looks more like original research--the false assumption that RGBW is "CMYK in reverse" and somehow has the same colour characteristics.) Rather, RGBW should have the exact same gamut as RGB, only with less saturation in colours with the most brightness. --GregE (talk) 03:50, 14 December 2012 (UTC)
replies: text: I agree - and as this has not been challenged or references added to the parenthesis in question, I'll just remove it. Tøpholm (talk) 12:05, 4 August 2016 (UTC)
thread_title:  Dubious 

message: I thought that subpixel rendering was available in Adobe Acrobat / Reader earlier than in Windows XP. In the Acrobat I think it was offered during initial setup by default. --pabouk (talk) 09:23, 8 January 2014 (UTC)
thread_title:  Subpixel rendering was first brought to public attention by Microsoft in Windows XP as ClearType? 

message: There should be some mention of its disadvantages. Maybe a whole section dedicated to it, even. Though I'm biased against ClearType and its kind. •ː• 3ICE •ː• 08:29, 29 November 2014 (UTC)
thread_title:  Criticism of subpixel rendering 

message: I have designed a fractal program that generates imagery with the option of oversampling with RGB or BGR subpixel rendering. It runs on any modern web browser. You can find this at www.fractalartdesign.com/fractal
The oversampling options are "none" (1x1), "good" (2x2), "detailed" (4x4), and "fine" (8x8) under the "Quality" menu. Exceeding 8x8 oversampling provides no further gain in clarity. When subpixel-rendering is engaged under the "Render" menu, the oversampling adjusts to 6x4 and 9x8 to distribute it over the three primaries, effectively tripling the horizontal resolution of the fractal. It is not engaged under the "none" or the "good" options, as applying subpixels in 3x1 or 3x2 oversampling causes marked color distortion.
It does make a difference in the detail of the rendered fractal on an LCD display. Subpixel-rendered images seem sharper. When rendering for print or publication, this option must be turned off to avoid the fringing artifacts.
I attempted to upload samples for consideration in the article, but Wikipedia rejected the uploads as "unknown" in appropriateness.  
Gsearle5 (talk) 20:21, 23 September 2016 (UTC)
thread_title:  Subpixel Rendering Fractal Program 

message: I'm not sure if this quite fits in with this topic, but it is very interesting in itself. I found references to an electronic slide viewer called VideoShow and its accompanying software, PictureIt, by a company called General Parametrics. One of the selling points was the control over the horizontal positioning of display elements by apparently addressing the individual phosphors on a CRT display, effectively increasing the horizontal resolution. Here are the news articles and reviews:
* Portable display system produces high-level presentation graphics, Mini-Micro Systems, July 1984
* From Pixels to Microdots, Byte, September 1984
* VideoShow Hones Your Image, Popular Computing, February 1985
--PaulBoddie (talk) 23:06, 15 August 2022 (UTC)
replies: text: The Byte article is describing a higher resolution horizontal signal and has nothing to do with subpixel resolution. I think you are confused by terms in that article as at the time the main technological hurdle was compression to use minimal memory, the analog signal was no problem.Spitzak (talk) 03:06, 28 September 2022 (UTC)
replies: text:  I acknowledge the technique of minimising memory usage to represent the image, but the rather superficial Byte article talks about pixel triads. Similarly, the Popular Computing article also mentions triads, noting that "MacroVision, however, treats each triad not as a unit but as three separately addressable microdots." So, aside from compression or other techniques concerned with representing an apparently high resolution image in restricted amounts of memory, there is also a technique involving the utilisation of individual phosphors. That latter technique is what I considered pertinent to this article. As for the analogue signal characteristics, I don't know what the signal being "no problem" is meant to say, but you can obviously increase the dot clock frequency. But on a colour display with a dot pitch that doesn't support a higher resolution, what does that do other than address subpixels directly? The fact that the Popular Computing article also talks about colour control indicates that they did more than just increase the frequency: that alone, as my home computer did when used with a television set decades ago, wouldn't have given such a level of control. --PaulBoddie (talk) 11:09, 28 September 2022 (UTC)
thread_title:  General Parametrics 

message: It's simply not true. Videogame artists have been taking advantage of subpixel rendering for decades. This is why SNES and PS1 era art looks so much better at 1:1 native resolution than blow up as raw bitmaps of square pixels. It's why people prefer low resolution displays like CRTs for those games. In fact, for years I was fascinated by Windows XPs "ClearType" on my CRT monitors. This was technology designed for CRT long before LCD monitors became commonplace. The fact that it also works on LCD, and everyone now uses LCD, doesn't imply it's for LCD only. The article would be more accurate if it simply said LCD/CRT without vaguely claiming there's a difference in their subpixel rendering abilities. There isn't. Habanero-tan (talk) 00:59, 26 September 2022 (UTC)
replies: text: Agreed. The article describes the topic as "rendering pixels to take into account the screen type's physical properties", and if you look at the General Parametrics devices mentioned above, that is apparently precisely what they do... with a CRT. Moreover, sub-pixel anti-aliasing was featured in the Acorn outline font manager to "increase the positioning resolution" of text in small font sizes, this largely being done independently of the display technology. Arguably, using specific characteristics of the display for positioning is just specialisation of more general subpixel rendering techniques. --PaulBoddie (talk) 23:18, 27 September 2022 (UTC)
replies: text:  No, you are confusing anti-aliasing with subpixel rendering. Spitzak (talk) 02:58, 28 September 2022 (UTC)
replies: text:  I am aware of the difference between the two techniques, and I will admit that Acorn's implementation did just anti-alias the text at different subpixel positions but limited itself to controlling the intensity of whole pixels, as opposed to employing a model that considered the display pixel structure. However, I think it is important to reference the antecedents of the described technique, which the first picture on the page tries to illustrate without such additional context. And as noted elsewhere, the microdots concept in General Parametrics' products looks rather more like a direct predecessor of the described technique, if not an actual earlier example. --PaulBoddie (talk) 11:24, 28 September 2022 (UTC)
thread_title:  Article needs a rewrite to remove incorrect assertions that it's an LCD thing and not as applicable to CRTs