Talk:Gamma correction
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is the formula given here the same power law relationship described in Gamma characteristic?
- Yes.
How about a link in the text here instead of a footnote? Or do we in fact need a seperate page for Gamma characteristic -- could we merge that into here & leave a redirect? -- Tarquin
Regarding the Linear intensity vs. Linear encoding table at the top, with IE 6.0, the text is black, making a portion of the left half of the table impossible to read.
I think we should unite this page with Gamma correction. Wikipedia is not a dictionary, so it would make no sense to have 2 articles dealing with the same issue. --Uri
I agree (I suggested the same thing on the other page ;-). Merge the text here into the other & leave a redirect. (or the other way round. I'm not sure which has precedence) -- Tarquin 07:22 Aug 18, 2002 (PDT)
- Perhaps move them both into Gamma (computer graphics)? --Uri
- I'd rather not, that's a title that no-one will ever remember. I suspect Gamma correction is most likely to be linked to.
- Well, I suppose you're right. I'll do the merge. --Uri
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limited signal bandwidth
The two images shown while speaking about monitors with an analogue input are great, since it shows that alternating black and white on one row does not work, due to monitor limitatios. This could be improved, however, in several ways:
1. It should state *which* one is correct (the horizontal lines).
2. It should state *how* to percieve the images (move back really far, if possible, since this is better than squinting, since you are not affecting your eyesight whatsoever by merely stepping back). This also goes for the gamma correction chart on the side (which someone has mentioned below, as they don't 'get it').
3. It should state that if you see two different shades, that you can have an affect on the shade that is wrong. Place the monitor in a lower resolution mode and / or lower refresh rate, and you may notice the shades become the same, as you would be reducing this artifact of analogue inputs.
4. It should explain why pages like this are *wrong*: http://freespace.virgin.net/hugo.elias/graphics/x_gamma.htm (because, even though it is a checkerboard pattern, it it the same thing as verticle lines, if you realize the monitor 'draws' the image one row at a time, completely independent of other rows). *Many* pages use this type of incorrect image. For my CRT, I get 1.3 gamma from these images, when it is actually 2.5! Wow.
137.186.22.215 15:04, 6 May 2005 (UTC)
(Non)Displayable symbols
Hello
With Microsoft IE under Windows (2YK Pro, but not limited to this brand), the operator "proportion" (mark up ∝ ∝"), as other math symbols from the iso-10646 char set, is simply displayed as the default white square("∝" should show a white square if you are using IE under Windows), used for non displayable symbols within the iso-8859-1 latin char set.
Is there a solution with some special font to be downloaded?
I suppose this is a general problem for all pages using iso-10646 symbols.
Jean Paul (gerard.jph@wanadoo.fr) 20040315
- I've no idea about Windows, but I replaced the equations with TeX versions, to be rendered as images. Unfortunately, due to a bug in the Wiki software, it won't render a "proportional" symbol, so I used the "similar to" symbol. -- Hankwang 08:54, 16 Mar 2004 (UTC)
- You need to install a font that has all the needed symbols, for IE and Microsoft Word that would be Arial Unicode, or Verdana Unicode. You can obtain those fonts from the Word setup. I don't know if Firefox supports special unicode fonts when freshly installed.
What this image supposed to be ?
Q: I don't get what the check-your-gamma-value graphic on the right side of the article is supposed to be. when i look at the image, i see lines on the left side, and blank fields with slightly different grey values on the right side. I can't tell what field has the same grey value as the line fild, as my brain doesn't fool me. am i supposed to blur the image (look unsharply at it)? thanks, --Abdull 19:28, 17 Jan 2005 (UTC)
A: As explained above in 'limited signal bandwidth', you are supposed to step back until your eye percieves the horizontal stripes as a solid color. Then, you can compare the left side and the right side. The squares that appear as one solid color, rather than two different colored squares next to each other, shows the gamma correction of your display. You'll notice your eye is very good at noticing even slight differences in colors. The page should explain this. 137.186.22.215 15:07, 6 May 2005 (UTC)
I edited Cyp's latest addition involving black and white stripes. The first image ("gammaaargh") has nothing to do with gamma correction, because it is composed entirely of black and white pixels and therefore says nothing about the monitor's linearity. The difference in the apparent brightnesses of the two squares is just a function of the monitor's analogue bandwidth. I left it in anyway, for the time being, because it's interesting, but it really belongs in some other article. The second image ("gammatest") is closer to a true gamma test, as it allows you to compare an apparent 50% luminance generated by alternating black and white pixels with solid areas of varying luminance. It says nothing about the linearity at values other than 50%, however. -- Heron 12:29, 30 May 2004 (UTC)
Why is there gamma correction
What is the reason for gamma correction? Does it have something to do with the Weber-Fechner law (or better: Stevens' power law), which deal with the fact that we freaky humans perceive stimuli logarithmically? --Abdull 11:52, 23 Mar 2005 (UTC)
Some curiosities
"The gamma function, or its inverse, has a slope of infinity at zero."
This http://en.wikipedia.org/wiki/Gamma_function gamma function? Since it's probably referring to the I ~ V^gamma instead, how do you get a slope of infinity at zero for that? To me the slope seems to approach zero at zero.
Another thing that confuses me is why is any gamma correction applied at all? The top chart with linear intensity and linear encoding clearly shows linear intensity looks wrong to the human eye. Besides, usually gamma is only corrected from 2.5 to 2.2 so even after correcting it's still not linear.