![]() | This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
Archive 1 |
The first formula gives sqrt(2/3) for r=1,g=0,b=0 -- not 1 as one would expect. It can be reduced to sqrt(2/3*(rr+gg+bb-rg-rb-bg)). Note that by using this formula yellow, cyan and magenta are never fully saturated. They all have values of sqrt(2/3). It appears the intent was to give the distance from the 0,0,0 to 1,1,1 line, which would be sqrt(2*(rr+gg+bb-rg-rb-bg)). Normalizing this yields sqrt(rr+gg+bb-rg-rb-bg), and fully saturated red, green, blue, yellow, cyan and magenta all return 1. Both pure white (1,1,1) and pure black (0,0,0) return 0.
In any case the second formula of (max(r,g,b)-min(r,g,b))/3(R+G+B) is what all software I have ever seen uses. Red, green, and blue have a saturation value of 1/3. Yellow, cyan and magenta have a saturation value of 1/6. Again, white, black and gray have saturation values of 0.
—Preceding unsigned comment added by Spitzak ( talk • contribs) but heavily modified by Wm 04:37, 4 September 2007 (UTC), which he shouldn't have done
If no values of R,G,B = 0, then saturation = Sqrt[(R-1)^2+(G-1)^2+(B-1)^2]/Sqrt[3]. This is the distance from white(RGB(1,1,1)).
If one value of R,G,B = 0, the problem becomes finding the distance to white in the relevent plane (e.g. if B=0, then saturation = Sqrt[(R-1)^2+(G-1)^2]/Sqrt[2]).
If two values are zero, then saturation equals the value present minus one.
Note that all values pass the test: Red, green, blue, yellow, cyan, magenta, and black all equal 1. White yields 0. This algorithm works because of the way we desaturate a specific color in RGB, namely, we manipulate only nonzero values. R,G,B values of zero mean that the corresponding primary is fully desaturated and will stay that way as we move toward the fully unsaturated RGB value of that particular color (white). In other words, if B=0, then moving R and G proportionally toward 0 desaturates yellow.
Wm 04:37, 4 September 2007 (UTC)
I'm getting a little frustrated by Wiki.
Anyway, the source is in the derivation above. It uses the following three definitions of saturation, which actually agree. Give me some time and I'll find in Wiki where the three definitions are actually equivalent:
1. Vividness of hue; degree of difference from a gray of the same lightness or brightness. Also called intensity. Dictionary.com
2. The vividness of a color's hue. Saturation measures the degree to which a color differs from a gray of the same darkness or lightness. Dictionary.com
3. In optics, the degree which colors of the same wavelength are differentiated from one another on the basis of purity which correlates with the amount of white present, such as red from pink. Dictionary.com
Here's some Mathematica code, if you're interested:
f3[r_, g_, b_] := Module[{num = 3, ret = 0, r1 = r, g1 = g, b1 = b},
num = num - If[r == 0, 1, 0]; If[r == 0, r1 = 1]; num = num - If[g == 0, 1, 0]; If[g == 0, g1 = 1]; num = num - If[b == 0, 1, 0]; If[b == 0, b1 = 1]; If[num == 0, Return[1], Return[Sqrt[(r1 - 1)^2 + (g1 - 1)^2 + (b1 - 1)^2]/Sqrt[num]] ]; ];
Anyway, this is consistent with the definition of saturation. If it's not useful, well, sorry. Anything else needs to be called something other than saturation.
Sorry about the trouble I've caused. This is my first experience with Wiki.
Wm 08:04, 4 September 2007 (UTC)
I've moved this article to "colorfulness", and will try in the next few days to put some better explanations up of the similarities and differences between saturation, chroma, and colorfulness. Maybe it would be worth emailing Mark Fairchild to ask for advice/diagrams/etc. This article could really generally use some better sourcing. -- jacobolus (t) 20:50, 19 September 2007 (UTC)
There is no explanation of the qmax function in the above section. It would be great if someone that knows how to compute this would add either the formula or a reference. I tried google and didn't find anything. Dhoerl 13:26, 5 October 2007 (UTC)
According to the hsl/hsv-system the graphic can't be write. By only(!) reducing saturation you will go from red to white, not black. What the graphic shows is a reduction of lightness. —Preceding unsigned comment added by DeeJay Antoine ( talk • contribs) 21:29, 5 June 2009 (UTC)
Starting with sentence 2, the lede says:
Huh?? (1) Colorfulness is "the difference between a color against gray"?? Is this supposed to mean the difference between a color and gray? -- But what would that mean? Does "gray" here refer to relatively bright gray (near white), or to relatively dark gray (near black), or to some mid-gray? Is "difference between" supposed to have some quantitative meaning? (2) According the the above quote from the article, "chroma" is 'the difference between a color against gray' 'relative to the brightness of another color....' "The difference between...relative to..." makes no sense. (3) According to the above, saturation is 'the difference between a color against gray' 'relative to [the color's] own brightness'. Again, makes no sense. And saturation has nothing to do with brightness -- it refers to (a transformation of) the ratio of a single-frequency hue to an equal-intensity mixture of all frequencies, that will generate the given color.
The first sentence of the lede says that the title term "colorfulness" occurs "[i]n colorimetry and color theory". Yet I can't find the word "colorfulness" in either one of those articles.
Therefore I suggest two things:
I was surprised to be redirected to an article titled "Colorfulness" when I looked up "saturation". "Colorfulness" is an awkward word used mainly, I suspect, by color scientists, when speaking about color science to a lay audience. It is the type of word that usually is preceded by a pause, and then followed by the phrase "if you will", or "for want of a better term". It is useful only as a "word" that everyone knows the meaning of (because it is made up of a well known and often used adjective, "colorful", turned into a noun by adding "ness" to it). Without it, it would be impossible to define saturation, chroma, and other terms in color science. It is not suitable as the title of an encyclopedia article, any more than "hotness" would be a suitable title for an article about heat. 124.149.80.237 ( talk) 13:39, 5 December 2011 (UTC)
The article was moved to Saturation (color theory) without discussion (that's where it came from a year ago if memory serves), and then moved back again (thanks for moving it back, Jacobolus). Let's don't repeat that. If there's a move desired, make a proposal here and we can talk about it. Dicklyon ( talk) 05:32, 22 August 2008 (UTC)
The result of the proposal was no move. Turns out that no one seems very interested in this requested move. I suggest that if another editor wants to move the page they start a fresh RM as the initial date of this request was back in December 2011, and this request is stale. -- PBS ( talk) 14:20, 15 September 2012 (UTC)
Colorfulness → Saturation (color theory) – Request made by user:Trevj on 28 December 2011 using template:movenotice on the article page. First reason given "No consensus for previous move to Colorfulness, which seems to have proved controversial" -- PBS ( talk) 14:43, 7 September 2012 (UTC)
There's a problem with the saturation formula right after reference 4. According to that formula, to be fully saturated, Luminance must equal zero. That can't be right. 72.29.218.2 ( talk) 18:52, 19 November 2014 (UTC)
The comment(s) below were originally left at Talk:Colorfulness/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.
merge with chromaticity |
Last edited at 01:51, 1 January 2012 (UTC). Substituted at 12:04, 29 April 2016 (UTC)
![]() | This is an archive of past discussions. Do not edit the contents of this page. If you wish to start a new discussion or revive an old one, please do so on the current talk page. |
Archive 1 |
The first formula gives sqrt(2/3) for r=1,g=0,b=0 -- not 1 as one would expect. It can be reduced to sqrt(2/3*(rr+gg+bb-rg-rb-bg)). Note that by using this formula yellow, cyan and magenta are never fully saturated. They all have values of sqrt(2/3). It appears the intent was to give the distance from the 0,0,0 to 1,1,1 line, which would be sqrt(2*(rr+gg+bb-rg-rb-bg)). Normalizing this yields sqrt(rr+gg+bb-rg-rb-bg), and fully saturated red, green, blue, yellow, cyan and magenta all return 1. Both pure white (1,1,1) and pure black (0,0,0) return 0.
In any case the second formula of (max(r,g,b)-min(r,g,b))/3(R+G+B) is what all software I have ever seen uses. Red, green, and blue have a saturation value of 1/3. Yellow, cyan and magenta have a saturation value of 1/6. Again, white, black and gray have saturation values of 0.
—Preceding unsigned comment added by Spitzak ( talk • contribs) but heavily modified by Wm 04:37, 4 September 2007 (UTC), which he shouldn't have done
If no values of R,G,B = 0, then saturation = Sqrt[(R-1)^2+(G-1)^2+(B-1)^2]/Sqrt[3]. This is the distance from white(RGB(1,1,1)).
If one value of R,G,B = 0, the problem becomes finding the distance to white in the relevent plane (e.g. if B=0, then saturation = Sqrt[(R-1)^2+(G-1)^2]/Sqrt[2]).
If two values are zero, then saturation equals the value present minus one.
Note that all values pass the test: Red, green, blue, yellow, cyan, magenta, and black all equal 1. White yields 0. This algorithm works because of the way we desaturate a specific color in RGB, namely, we manipulate only nonzero values. R,G,B values of zero mean that the corresponding primary is fully desaturated and will stay that way as we move toward the fully unsaturated RGB value of that particular color (white). In other words, if B=0, then moving R and G proportionally toward 0 desaturates yellow.
Wm 04:37, 4 September 2007 (UTC)
I'm getting a little frustrated by Wiki.
Anyway, the source is in the derivation above. It uses the following three definitions of saturation, which actually agree. Give me some time and I'll find in Wiki where the three definitions are actually equivalent:
1. Vividness of hue; degree of difference from a gray of the same lightness or brightness. Also called intensity. Dictionary.com
2. The vividness of a color's hue. Saturation measures the degree to which a color differs from a gray of the same darkness or lightness. Dictionary.com
3. In optics, the degree which colors of the same wavelength are differentiated from one another on the basis of purity which correlates with the amount of white present, such as red from pink. Dictionary.com
Here's some Mathematica code, if you're interested:
f3[r_, g_, b_] := Module[{num = 3, ret = 0, r1 = r, g1 = g, b1 = b},
num = num - If[r == 0, 1, 0]; If[r == 0, r1 = 1]; num = num - If[g == 0, 1, 0]; If[g == 0, g1 = 1]; num = num - If[b == 0, 1, 0]; If[b == 0, b1 = 1]; If[num == 0, Return[1], Return[Sqrt[(r1 - 1)^2 + (g1 - 1)^2 + (b1 - 1)^2]/Sqrt[num]] ]; ];
Anyway, this is consistent with the definition of saturation. If it's not useful, well, sorry. Anything else needs to be called something other than saturation.
Sorry about the trouble I've caused. This is my first experience with Wiki.
Wm 08:04, 4 September 2007 (UTC)
I've moved this article to "colorfulness", and will try in the next few days to put some better explanations up of the similarities and differences between saturation, chroma, and colorfulness. Maybe it would be worth emailing Mark Fairchild to ask for advice/diagrams/etc. This article could really generally use some better sourcing. -- jacobolus (t) 20:50, 19 September 2007 (UTC)
There is no explanation of the qmax function in the above section. It would be great if someone that knows how to compute this would add either the formula or a reference. I tried google and didn't find anything. Dhoerl 13:26, 5 October 2007 (UTC)
According to the hsl/hsv-system the graphic can't be write. By only(!) reducing saturation you will go from red to white, not black. What the graphic shows is a reduction of lightness. —Preceding unsigned comment added by DeeJay Antoine ( talk • contribs) 21:29, 5 June 2009 (UTC)
Starting with sentence 2, the lede says:
Huh?? (1) Colorfulness is "the difference between a color against gray"?? Is this supposed to mean the difference between a color and gray? -- But what would that mean? Does "gray" here refer to relatively bright gray (near white), or to relatively dark gray (near black), or to some mid-gray? Is "difference between" supposed to have some quantitative meaning? (2) According the the above quote from the article, "chroma" is 'the difference between a color against gray' 'relative to the brightness of another color....' "The difference between...relative to..." makes no sense. (3) According to the above, saturation is 'the difference between a color against gray' 'relative to [the color's] own brightness'. Again, makes no sense. And saturation has nothing to do with brightness -- it refers to (a transformation of) the ratio of a single-frequency hue to an equal-intensity mixture of all frequencies, that will generate the given color.
The first sentence of the lede says that the title term "colorfulness" occurs "[i]n colorimetry and color theory". Yet I can't find the word "colorfulness" in either one of those articles.
Therefore I suggest two things:
I was surprised to be redirected to an article titled "Colorfulness" when I looked up "saturation". "Colorfulness" is an awkward word used mainly, I suspect, by color scientists, when speaking about color science to a lay audience. It is the type of word that usually is preceded by a pause, and then followed by the phrase "if you will", or "for want of a better term". It is useful only as a "word" that everyone knows the meaning of (because it is made up of a well known and often used adjective, "colorful", turned into a noun by adding "ness" to it). Without it, it would be impossible to define saturation, chroma, and other terms in color science. It is not suitable as the title of an encyclopedia article, any more than "hotness" would be a suitable title for an article about heat. 124.149.80.237 ( talk) 13:39, 5 December 2011 (UTC)
The article was moved to Saturation (color theory) without discussion (that's where it came from a year ago if memory serves), and then moved back again (thanks for moving it back, Jacobolus). Let's don't repeat that. If there's a move desired, make a proposal here and we can talk about it. Dicklyon ( talk) 05:32, 22 August 2008 (UTC)
The result of the proposal was no move. Turns out that no one seems very interested in this requested move. I suggest that if another editor wants to move the page they start a fresh RM as the initial date of this request was back in December 2011, and this request is stale. -- PBS ( talk) 14:20, 15 September 2012 (UTC)
Colorfulness → Saturation (color theory) – Request made by user:Trevj on 28 December 2011 using template:movenotice on the article page. First reason given "No consensus for previous move to Colorfulness, which seems to have proved controversial" -- PBS ( talk) 14:43, 7 September 2012 (UTC)
There's a problem with the saturation formula right after reference 4. According to that formula, to be fully saturated, Luminance must equal zero. That can't be right. 72.29.218.2 ( talk) 18:52, 19 November 2014 (UTC)
The comment(s) below were originally left at Talk:Colorfulness/Comments, and are posted here for posterity. Following several discussions in past years, these subpages are now deprecated. The comments may be irrelevant or outdated; if so, please feel free to remove this section.
merge with chromaticity |
Last edited at 01:51, 1 January 2012 (UTC). Substituted at 12:04, 29 April 2016 (UTC)