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04/15/2006 02:12:27 AM · #1 |
I know what it does; increasing it makes the colors more bold while decreasing it makes them more muted. That has been enough for me to use it for some time, but while working over a photo earlier I suddenly realized I have no idea what saturation is.
So, help me out -- at least point me in the right direction -- what is saturation.
David
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04/15/2006 02:19:00 AM · #2 |
im thinkin you need to be more specific... desaturating something will take out the color in it, making it b/w. Saturating something will increase that color, if you do this too much it causes the color to get blown out and too strong.
you pretty much had it right though. This community is full of people who want to help, but try being more specific, and you'll get better answers :)
-Dan
edit to add: theres also selective saturation and desaturation...
Message edited by author 2006-04-15 02:19:39. |
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04/15/2006 02:49:45 AM · #3 |
Color saturation refers to the intensity of a specific hue. As you increase the saturation, you are effectively slathering more of the same color on the work surface. Think of painting with thin paint; the more layers you put on, the more intense the color becomes.
In photoshop's hue/saturation dialogue box you are given a number of color channels which you may increase or decrease the saturation of. You can, effectively, add more red wherever there already is red, or remove red from where there already is red, or using the "hue" slider you may change the actual color value that PS assigns to the colors it has tagged as red.
In photoshop's selective color dialogue box you can much more precisely control the hues of each represented color channel, but your control over saturation is limited here. So, often, you may use both hue/saturation and selective color on the same image to completely control the rendering of the colors of the image.
R.
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04/15/2006 07:53:31 AM · #4 |
Thanks for your replies.
When asking about a confusion, it is often hard to find the right question to ask. :( Let me try again - and sorry for what will likely be verbose, but I did try brevity.
Between your replies and something my wife said about selective desaturation ("like when they keep the dress yellow and move the rest to grey"), I think I may have a better grasp on it. Or at least be able to ask a better question. I emphasized the part of what my wife said that caught my attention and gave direction to my investigations.
I see now that I was trying to understand saturation as being a change in value of the color in question, much like tone is a simple increase or decrease in the value of the pixel but only one or two of the component colors. Changing an individual color channel will likely change the hue as well as the saturation, so it doesn't seem to be that simple. I present here in bulletted format where my observations and reasoning took me, presented so someone can tell me if I went off-base somewhere along the line.
- Every color has three color channels (RGB) and each of these channels has a tonal value for that channel.
- The middle tone of the channels, (highest tonal value+lowest tonal value)/2, is the tone of the color.
- The three-way ratio of distance the three channels are from the tone of the color is the hue.
- The distance between the highest valued channel and the lowest valued channel is the intensity or saturation of the color.
- The less distance between the highest and lowest toned channels the less saturated the color, the greater the distance the greater the saturation.
- A color is over saturated when one of it's channels has reached one of the extremes (0 or 255, for an 8-bit color).
- The possible saturation is greatest in the middle tones is reduced to nothing at the extreme tones (black and white).
That last one is observation I find most interesting, and leads me to believe bringing the tone in toward the middle will require an increase in saturation to keep the color looking natural -- and likewise, moving the tone out toward the edges will require a reduction in saturation. For example, if bringing a nearly blown sky from zone 9 in to zone 7 to increase the detail, an increase in saturation will also be needed to keep it from appearing washed out.
This seems to agree with my limited experience, but I would love to here if it holds true for others as well. If it does, it is one more step toward my understanding how to work with zones on a color image.
So ... what do you think? Am I close to understanding saturation?
David
Message edited by author 2006-04-16 05:42:46.
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04/15/2006 04:06:35 PM · #5 |
... or maybe not. hmmm.
David
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04/15/2006 04:16:16 PM · #6 |
Originally posted by David.C:
Thanks for your replies.
That last one is observation I find most interesting, and leads me to believe bringing the tone in toward the middle will require an increase in saturation to keep the color looking natural -- and likewise, moving the tone out toward the edges will require a reduction in saturation. For example, if bringing a nearly blown sky from zone 9 in to zone 7 to increase the detail, an increase in saturation will also be needed to keep it from appearing washed out.
This seems to agree with my limited experience, but I would love to here if it holds true for others as well. If it does, it is one more step toward my understanding how to work with zones on a color image.
So ... what do you think? Am I close to understanding saturation?
David |
Jaysus, most of that I don't have a clue. Try PMing Kirbic and linking him to this thread, he might know.
However, the part I've quoted above doesn't sound right to me, empirically. I've noticed that when I lighten OR darken a color channel in hue/saturation, I need to increase the saturation to hold a natural color. The more I lighten/darken, the more I need to saturate.
R.
Message edited by author 2006-04-15 16:16:44.
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04/15/2006 04:26:50 PM · #7 |
| Saturation is the intensity of the hue with respect to gray of the same luminosity. |
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04/16/2006 06:14:48 AM · #8 |
Originally posted by ElGordo:
Saturation is the intensity of the hue with respect to gray of the same luminosity. |
Yes, that agrees with my observations described above. It seems in a lot of ways saturation can be thought of as a sub-pixel contrast, as the greater the difference in tone from the darkest channel to the lightest one determines the intensity.
Originally posted by Bear_Music:
Originally posted by David.C:
Thanks for your replies.
That last one is observation I find most interesting, and leads me to believe bringing the tone in toward the middle will require an increase in saturation to keep the color looking natural -- and likewise, moving the tone out toward the edges will require a reduction in saturation. For example, if bringing a nearly blown sky from zone 9 in to zone 7 to increase the detail, an increase in saturation will also be needed to keep it from appearing washed out.
This seems to agree with my limited experience, but I would love to here if it holds true for others as well. If it does, it is one more step toward my understanding how to work with zones on a color image.
So ... what do you think? Am I close to understanding saturation?
David |
Jaysus, most of that I don't have a clue. Try PMing Kirbic and linking him to this thread, he might know.
However, the part I've quoted above doesn't sound right to me, empirically. I've noticed that when I lighten OR darken a color channel in hue/saturation, I need to increase the saturation to hold a natural color. The more I lighten/darken, the more I need to saturate.
R. |
Sorry about that, when searching for an understanding I tend to dive deep until I find something solid to grab hold of and then build back up from there.
Your empirical experience struck me as odd though, so I went back and looked more closely at what the individual controls on the hue/saturation dialog actually do. What I found was nearly as strange.
The hue slider moves the individual channels, which causes the hue to move along the color bar at the bottom. It does this without changing the saturation or tone of the color.
The saturation slider shifts the tone of the individual channels in or out to increase or decrease the difference, but it does this without changing the hue or the tone of the color.
The lightness slider increases the tone of the color by moving the tones of the two lower toned channels proportionally closer to the brighter toned channel. This is what makes it strange -- while it doesn't alter the hue of the color, moving only one side of the color changes the intensity. Decreasing the tone of th color is done similarly by moving the two lighter toned channels toward the darker one. This means any change in tone made with the lightness slider will decrease the saturation of the color -- which agrees with your empirical observations.
I would have thought the slider would have simply moved all three channels up or down in tone together. Doing this would not have affected the hue or saturation at all, but to get this behaviour the brightness slider in the Brightness/Contrast dialog must be used.
David
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