Effects of saturation on contrast

It appears that increasing saturation decreases contrast. Is that true? If so, why would that be?

Thanks,
Ron

"" wrote:

It appears that increasing saturation decreases contrast. Is that true? If so, why would that be?

The RGB colorspace mixes color and luminosity information in each channel. Therefore, changes in color will inevitably change the luminosity as well. Increasing saturation beyond a certain level results in a loss of luminosity variation and consequently, a loss of contrast.
In L*a*b, color information is independent of luminosity information, they reside in different channels. Therefore, color can be manipulated without influencing luminosity and vice versa.
To learn more about this, try the following. Put a Hue,Saturation adjustment layer on top of some image in RGB mode. Do not change anything at first, but set the layer mode to luminosity first. Now open the dialog window again and move the saturation slider to its extremes. You will observe a change in the luminosity of the image with a considerable decrease of contrast when saturation is brought to a maximum. Now do the same thing in LAB (edit>convert to profile>LAB). In this colorspace, you won't see a change in luminosity/contrast at all, irrespective of how much you change saturation. However,be warned that it LAB it is possible to create virtual colors. There is no such thing as a bright green with zero luminosity in the real world. However, PS tries to optimize the rendition of such colors by compromising between luminosity and saturation. The result is quite often much better than what can be achieved in RGB.
The LAB mode has great advantages for image manipulation. You may read more about this in Dan Margulis' book on the topic.

Peter

Peter Wollenberg wrote:

"" wrote:

It appears that increasing saturation decreases contrast. Is that true? If so, why would that be?

The RGB colorspace mixes color and luminosity information in each channel. Therefore, changes in color will inevitably change the luminosity as well. Increasing saturation beyond a certain level results in a loss of luminosity variation and consequently, a loss of contrast.

I am glad you said this because it made me realize that I do not understand how luminance is derived from the R,G,B trio in RGB color space. I have been thinking of saturation as the radius of the cone, hue at the direction (center out), and luminance as the distance from the tip. I guess the bigger the numbers the further from the tip, but I think that what you are saying is that for each color value in a given channel there will be an associated level of luminosity - and that as I increase the value of the color the less latitude I will have for changes in luminance? Which I do not understand but at least I know what to read up on.

In L*a*b, color information is independent of luminosity information, they reside in different channels. Therefore, color can be manipulated without influencing luminosity and vice versa.

It seems like the implication of this is that, at least in the context of my original question, is that luminosity is directly related to contrast. Which makes me wonder what is the relationship between contrast and detail. Again you have given me direction on what to study.

To learn more about this, try the following. Put a Hue,Saturation adjustment layer on top of some image in RGB mode. Do not change anything at first, but set the layer mode to luminosity first. Now open the dialog window again and move the saturation slider to its extremes. You will observe a change in the luminosity of the image with a considerable decrease of contrast when saturation is brought to a maximum. Now do the same thing in LAB (edit>convert to profile>LAB). In this colorspace, you won't see a change in luminosity/contrast at all, irrespective of how much you change saturation.

This was a great exercise.

that it LAB it is possible to create virtual colors. There is no such thing as a bright green with zero luminosity in the real world. However, PS tries to optimize the rendition of such colors by compromising between luminosity and saturation. The result is quite often much better than what can be achieved in RGB.
The LAB mode has great advantages for image manipulation. You may read more about this in Dan Margulis' book on the topic.

I think you are saying it is possible to edit in LAB then use the out of gamut conversion or transformation algorithms in PS to achieve more desirable results. I remember reading something about these algorithms, perception and absolute seems to ring a bell but I will have to try to find the article again. I would love to have the book, i will put it on my list, but for now it is out of reach.

One thing I noticed when I was working though your exercise was that if I could somehow take the highlights from the 'Red' channel in RGB space, and combine that with the midtones and shadows from the 'Lightness' channel from LAB space I would have the perfect Black and White photo. The highlights from the red channel are so delicate and lovely while the midtones and shadows fromt he lightness channel are so sharp and rich. I doubt if that would always hold true but in the case of the picture I was working with it would be great.

Thank you for all the great informtion,
Ron

Peter

Peter Wollenberg wrote:

The RGB colorspace mixes color and luminosity information in each channel. Therefore, changes in color will inevitably change the luminosity as well.

That is one way to explain the situation. Another way to explain it is to say that the editing tools of Photoshop do not behave correctly.

Naturally, a control that has a label such as Lightness or Saturation or Hue etc should affect to that particular property of colors and to nothing else, and should do so exactly similarly no matter how the image data happens to be coded (no matter in what ever RGB or Lab etc space the data happens to be).

In L*a*b, color information is independent of luminosity information, they reside in different channels.

That is not correct, in the Photoshop the Lab space has three channels (Lightness, a, and b) but the Lightness is not independent from the a and b channels. In order to demonstrate this I created 256 somewhat random patches from the base color Lab==50,0,0 by changing only the a and b channels (using the Saturation and/or Hue controls) in the Lab mode of Photoshop (with the gamut warning tool active for sadRGB so the patches are all inside CRT gamut).

Here is the result as a JPG:
http://www.aim-dtp.net/aim/temp/lab-luminance.jpg
The base color is at the top left corner. The patches clearly appear to have way different lightness, some patches appear to be very dark, some very "bright".

Here is the original as a Lab mode PSD document in case you want to verify the Lab values of the patches yourself:
http://www.aim-dtp.net/aim/temp/lab-luminance.psd

Therefore, color can be manipulated without influencing luminosity and vice versa.

As above, no. Affecting to the Lightness does affect to the hue and/or saturation ... I could make a demonstration about this also but it is somewhat more difficult to evaluate by the unaided eye.

The LAB mode has great advantages for image manipulation.

Actually no. There are only a couple of procedures that provide some marginal benefit in the Lab space. The Lab space has major problems with out of gamut issue, even a very slight adjustment can throw plenty of colors right out from this universe, the Lab space specifies a huge amount of "colors" that are out of the gamut of the human vision and out of the gamut of the CIE color model that the current color-management is based on. It has a discontinuity point in the transfer function at the dark end etc etc. Generally it is the very best to totally avoid working in the Lab space.

Timo Autiokari

Timo Autiokari wrote:

....

Naturally, a control that has a label such as Lightness or Saturation or Hue etc should affect to that particular property of colors and to nothing else, and should do so exactly similarly no matter how the image data happens to be coded (no matter in what ever RGB or Lab etc space the data happens to be).

IMNSHO this is an inherent problem of the RGB space and not of PS. It is impossible to increase the saturation and keep the hue _and_ the luminosity constant in RGB, if one of the channels approaches its extremes. 255R 128G 128B can only be made more red by decreasing the G and B values, and since the luminosity is represented by R + G + B the increase in saturation inevitably results in a decrease of luminosity.

In L*a*b, color information is independent of luminosity information, they reside in different channels.

That is not correct, in the Photoshop the Lab space has three channels (Lightness, a, and b) but the Lightness is not independent from the a and b channels.

....

Here is the original as a Lab mode PSD document in case you want to verify the Lab values of the patches yourself:
http://www.aim-dtp.net/aim/temp/lab-luminance.psd

When I opened this image and looked at the L-channel, I found it was evenly grey. Evidently, the lightness _is_ unchanged in your example.

Therefore, color can be manipulated without influencing luminosity and vice versa.

As above, no. Affecting to the Lightness does affect to the hue and/or saturation ... I could make a demonstration about this also but it is somewhat more difficult to evaluate by the unaided eye.

Which means that it is irrelevant for practical purposes?

The LAB mode has great advantages for image manipulation.

Actually no. There are only a couple of procedures that provide some marginal benefit in the Lab space. The Lab space has major problems with out of gamut issue, even a very slight adjustment can throw plenty of colors right out from this universe, the Lab space specifies a huge amount of "colors" that are out of the gamut of the human vision and out of the gamut of the CIE color model that the current color-management is based on. It has a discontinuity point in the transfer function at the dark end etc etc. Generally it is the very best to totally avoid working in the Lab space.

Well, I use PS to work on real life photographs and not on computer created swatches and, working in L*a*b I do get consistently better results from these than in RGB. Actually, I was able to obtain excellent results from shots which I trashed earlier, when I did not yet know about the possibilities of L*a*b and tried to improve them in RGB or CMYK.
I think you didn't read the book, which we are talking about. Margulis devotes several chapters to the pitfalls of L*a*b and the "impossible colors". He makes very clear what the advantages and disatvantages of the various color spaces are and actually shows impressive examples of how RGB and CMYK may outperform L*a*b in certain situations, how the advantages of all spaces can be tied together for even better results, and how the apparent limitations of any of them can be turned into an advantage with certain retouching problems.
I have a very pragmatic approach to my work, and as long as my results are superior after a L*a*b treatment within a fraction of the time it would have taken to get a mediocre result in CMYK or RGB, I care a shit about any theoretical reasoning, why this should not have happened.

Peter

I decided to check the contra positive, which should always be true, of the original statement that - increasing saturation decreases contrast. That is, increasing contrast decreases saturation. I did this by looking at the height of the color channels (wouldn't that be saturation?) while sliding the gamma slider to the right in 'Levels'. This turned out to not to be a valid test since the saturation (height) only increased where the tonal distribution was being squeezed. Where the distribution was being stretched the saturation decreased. I could not figure out how to interpret those results. Not being one to let my ignorance get in the way I proceeded to do the same test in LAB. To my surprise ONLY the L channel was affected. The color channels were not changed at all. This seems to back up what Peter was saying both in terms of the limitations of RGB space and in potential benefits of editing in LAB.

Brgds,
Ron

You can see an illustration of Peter's point in the Color Picker. Start with a totally desaturated color and an arbitrary hue (I'll use 0°). Increase the saturation slider and watch what happens to the R, G and B values. Photoshop saturates color by decreasing the complement. Since 0° is a red, the red value stays constant and the green and blue values decrease as you drag the saturation slider up. If you started with red at 255 and saturation at 0, the desaturated version is white (255,255,255). By the time you drag the saturation to 100%, you'd have 255,0,0.

Tom Nelson
Tom Nelson Photography

In article , Peter Wollenberg
wrote:

IMNSHO this is an inherent problem of the RGB space and not of PS. It is impossible to increase the saturation and keep the hue _and_ the luminosity constant in RGB, if one of the channels approaches its extremes. 255R 128G 128B can only be made more red by decreasing the G and B values, and since the luminosity is represented by R + G + B the increase in saturation inevitably results in a decrease of luminosity.

Peter Wollenberg wrote:

IMNSHO this is an inherent problem of the RGB space and not of PS. It is impossible to increase the saturation and keep the hue _and_ the luminosity constant in RGB, if one of the channels approaches its extremes.

That is not an inherent problem of the RGB space, the same will happen in what ever color space when any of the channels gets clipped.

When I opened this image and looked at the L-channel, I found it was evenly grey. Evidently, the lightness _is_ unchanged in your example.

The purpose of this image was to show you that even if the numeric L value of all the patches is exactly the same the appearance of the lightness (for your vision) of the patches is not at all the same.

Just look at the image, some patches clearly appear to be much more lighter than the 50,0,0 patch and some appear to be much more darker. So a change to the a and/or b channel(s) does affect to the lightness of the color (but not to the numeric L value of the color). So something is very wrong, and it is that the Lab channel that is called as the L or Lightness channel is not at all a true Lightness channel.

Timo Autiokari

wrote:

I did this by looking at the height of the color
channels (wouldn't that be saturation?)

The "height" of the histogram of the color channels does not describe the saturation of the colors.

while sliding the gamma slider to the right in 'Levels'.

That control does not change the saturation of the colors but makes the colors of an image (that has correct colors) to be incorrect. use e.g. the Saturation slider in the Hue/Saturation dialog to adjust the saturation.

This turned out to not to be a valid test since the saturation (height) only increased where the tonal distribution was being squeezed.

Correct, gamma change just makes a correct image to be incorrect, it is not possible to assess the properties of colors correctly from image data that is incorrect.

I proceeded to do the same test in LAB. To my
surprise ONLY the L channel was affected.

So, you adjusted the gamma slider in the Levels dialog in Lab space. Now, please open that Lab image again, then go to the Levels dialog.You will find out that in the Channels dropdown the default channel (that is to be adjusted) is "Lightness". So, when you adjust the Lightness channel then of course only the numerical values on the Lightness channel will change. No surprise in that. In the RGB mode the default channel in that Channels dropdown of the Levels dialog is "RGB" so all numerical values on al the three channels are adjusted.

The color channels were not changed at all.

The numerical values of the color channels remain unchanged of course. But look at the actual colors in the image (as shown by your monitor) while you adjust the Lightness channel, both the hue and the saturation will change but only the Lightness of the colors (as shown by your monitor) should be changing.

This seems to back up what Peter was saying both in terms of the limitations of RGB space and in potential benefits of editing in LAB.

There are many RGB spaces, some of them indeed do limit the gamut (saturation) some do not. Some RGB spaces are better for editing purposes and some are worse, this depends on the transfer function of the particular RGB space.

Lab space does not (in practice) limit the gamut but for editing purposes it is a _very_ bad space due to the extremely cumberome non-linear coding of the Lab space and due to the fact that nearly all of the editing operations of Photoshop are designed for editing linear RGB data only. While editing in the Lab space you will very easily get large luminance and/or hue and/or saturation errors even if the numerical Lab values do not indicate that at all.

Timo Autiokari

I agree that I do see changes in saturation as a result of changing the gamma of the Lightness channel. But now all this has me wondering - how is it possible to edit in anything other than sRGB since that is gamut of the monitor? How can we even look at LAB space using a CRT display device? In other words, why don't all color spaces look like sRGB?

Thanks,
Ron

wrote:

how is it possible to edit in anything other than
sRGB since that is gamut of the monitor?

sadRGB is just an approximation of CRT monitors but the the worst of them. It is a very bad color-space for image editing (it has the slope-limiting in the dark-end and it is highly non-linear).

Editing in a color space that has larger gamut (than what the gamut of the display is) indeed gives some obvious trouble. Adobes provides some tools that help in this, mainly:

1) Proofing & gamut warning

2) The "Desaturate Monitor Color by" -inputbox in the ColorManagement/MoreOptions (or ColorManagement/Advanced) section. But is it difficult to work with.

How can we even look at LAB space using a CRT display device?

Monitor only shows what can.For CRT monitors a very good appriximation is the nativePC profile (Primaries=Trinitron, Gamma=2.5, Whitepoint=D65). Color that that are out-of-gamut from that are shown by Photoshop with one or more channels clipped (so they are shown inaccurately).

In other words, why don't all color spaces look like sRGB?

Short answer to this could be: Because we have color-management.

Now, sadRGB is just one color-spesification among others. Color-specifications are the mathematical translations between the numerical values of the colors and the visual appearance of those colors. For example:

the code RGB== 50,100,150 in the sadRGB -space outputs a certain color on the monitor, that very same color is specified as:

RGB== 68,122,160 in the nativePC -space,
RGB==70,100,147 in the adobeRGB -space,
RGB==31,31,72 in the CIE 1931 d65 gamma 1.0 -space.

RGB working-spaces normally/currently consists three parameters:

-the primaries (they specify the tri-chromatic gamut)
-the gamma (or more generally the tonal reproduction curve or trasnfer curve)
-the whitepoint

So different RGB spaces behave differently, e.g. the same editing operations in different RGB spaces give different results.

Why then do we have so many different RGB spaces? There are at least historical, practicality, marketing, political, religious (based on pure firm belief) and technical reasons for that.

Timo Autiokari

Thank you for your time and all the valuable information. I read your reply twice and got very sleepy. So I will sleep for a while then read it again then Wiki/Google some terms then read it again then look into the Photoshop tools you mentioned. Eventually I will get it.

Brgds,
Ron

wrote in message

I decided to check the contra positive, which should always be true, of the original statement that - increasing saturation decreases contrast. That is, increasing contrast decreases saturation. I did this by looking at the height of the color channels (wouldn't that be saturation?) while sliding the gamma slider to the right in 'Levels'. This turned out to not to be a valid test since the saturation (height) only increased where the tonal distribution was being squeezed. Where the distribution was being stretched the saturation decreased. I could not figure out how to interpret those results.

The height will always increase when the tonal range is compressed, because there are more pixels at a particular value. It is not related to saturation. The min and max values of the histogram are often equated with saturation, but this is only a loose relationship. Conclusions based on interpreting a histogram, that are not also based on the appearance of the image, should be ignored.

Not being one to let my ignorance get in the way I proceeded to do the same test in LAB. To my surprise ONLY the L channel was affected. The color channels were not changed at all. This seems to back up what Peter was saying both in terms of the limitations of RGB space and in potential benefits of editing in LAB.

This is not surprising, the slider only affects the lightness channel, and is not hooked up to the a or b channels. The ability to alter Lightness without changing color is indeed a major advantage of Lab, and the reason I use it for the majority of my own images. If you bought Photoshop, you have paid for support for Lab, and it's worth your while to learn to use it. (The same goes for CMYK). But Lab is not the best choice for all images.

In RGB, bumping the contrast of an image generally increases the color saturation. In practical terms, this makes RGB an ideal color space for dealing with underexposed images. Since such images are generally lacking in color as well as brightness, increasing contrast has the happy side effect of increasing color. The same is true of washed out images - making them darker by moving the black end of the RGB curve increases contrast, and adds saturation.

Lab is my default color space for color correction work. If the saturation is already about right, RGB may add or remove saturation inappropriately. Most of my camera images benefit from a saturation boost, even though the exposure is correct. In addition to saturation, hue angle can also change as a side effect of any RGB correction. This is the main reason you may find yourself accidentally getting very saturated red or orange skin tones when correcting in RGB.

HSB used to be directly supported in Photoshop, and the ability to manipulate saturation using a curve is very effective for certain images, such as landscapes. HSB has the interesting feature that increasing contrast can either add or remove saturation, depending on whether the contrast change makes the image darker or brighter.
--

Mike Russell
www.curvemeister.com/forum/

Mike Russell wrote:

The ability to alter Lightness without changing
color is indeed a major advantage of Lab

Please do this test:

1) Take an underexposed raw shot of a color input target (e.g. the Kodak Q60). Use a strong underxposure, say -4EV, so that you will see the errors clearly.
2) Convert the raw shot into a RGB color-space (but not to the sadRGB) and do not let the raw converter to correct the underexposure.
3) Open the converted image to Photoshop.
4) make a duplicate of that and convert the duplicate to Lab.
5) Scale up the RGB mode image using the right input levels slider of
the "RGB channel"--> the appearance of the image will pretty closely match the appearance of the target itself.
6) Scale up the Lab mode image similarly using the right input levels slider of the "Lightness channel" --> the image shows _very_ larger luminance, hue and saturation errors.

Please do the above experiment, you will learn that it is _not_ possible to change the Lightness without changing "color" in the Lab mode.

In this context the commonplace expression "color" is way too loose term. What we refer to with (reflected or self luminous) "color" is actually composed by three properties: Luminance, hue, and saturation. The luminance of a dark surface is low and the luminance of a white surface (e.g. illuminated by the sun) is high. The hue of the strawberry is red and the hue of the grass is green. Pink is less saturated red than what the saturation of the red of a strawberry is.

A change (or scaling) on the "L"channel in the Lab space _does_ affect, very strongly indeed, to both the hue and the saturation, it is a widely spread misunderstanding that it would not. I have already presented a demonstration that shows that when the hue and/or saturation is changed in the Lab space then the luminance will change also. The contrary is _equally_ true, a change on the "L" channel will also change the hue and/or saturation of the color. Naturally the numerical values on the "a" and "b" channels do not change due to a change on the "L" channel but the displayed hue and/or saturation will, a great deal. Note that the "a" and "b" channels are not hue nor saturation -channels, they are just arbitrary numerical scales.

The related operation in a RGB space is a change (or scaling) on the "RGB channel". The result depends on the properties of the particular RGB space. In case the RGB space is linear (has gamma 1.0 transfer function) or an accurate mathematical gamma function then the hue and/or saturation are not affected at all due to that operation and the lumimance scaling happens properly. In case of the sadRGB and the Lab spaces, hue and/or saturation errors are induced and the scaling of the luminance happens incorrectly.

In RGB, bumping the contrast of an image
generally increases the color saturation.

To what operation do you refer to by "bumping the contrast"? With digital images the "contrast" is somewhat a difficult property to be adjusted without creating some kind of errors, no matter in what color space you perform this such operation. In the real life it is much more easy to increase contrast, you just add more light to the scene. In digital imaging light can not be added freely since there is the upper limit (255,255,255), so other kind of rendering has to be performed in order to "bump up the contrast".

I suspect the above could initiate some discussion about the property called contrast, so: Take absolutely all the light away from a scene, the result is that absolutely no contrast is available from the scene. Lit up a candle, now there is just a little of contrast available from the scene. Lit up a sun, plenty of contrast is available.

In practical terms, this makes RGB an ideal color space for dealing with

Correctly chosen RGB space is ideal for all image manipulation.

underexposed images. Since such images are generally lacking in color as well as brightness,

Underexposed images are just that, underexposed. They do not lack "color", nor saturation nor hue. They do not lack even the luminance. The digital coding of underexposed shots simply is scaled down due to the underexposure.

The same is true of washed out images - making them darker by moving the black end of the RGB curve increases contrast, and adds saturation.

Such adjustment moves the blackpoint of the coding upwards, this will _clip_ any data that there might be in that clipped portion of the dark end. In addition, if you do this in non-linear working-space then the "image-gamma" (a.k.a. "file-gamma") is affected resulting errors to all three color properties. Blackpoint adjustment should be performed only when the blackpoint is incorrectly coded.

If the saturation is already about right, RGB may add or remove saturation inappropriately. [...] In addition to saturation, hue angle can also change as a side effect of any RGB correction. [...] This is the main reason you may find yourself accidentally getting very saturated red or orange skin
tones when correcting in RGB.

Editing work in a non-linear RGB working-space will create such (and other) errors, editing work in the Lab space also does so. Editing work in the linear RGB space either completely avoids or at least minimizes all such errors.

Timo Autiokari
http://www.aim-dtp.net

wrote in message
....

Editing work in a non-linear RGB working-space will create such (and other) errors, editing work in the Lab space also does so. Editing work in the linear RGB space either completely avoids or at least minimizes all such errors.

I won't respond in detail to Timo's comments, if only because the topic has begun to stray from the original poster's concerns about changes in saturation due to interaction with other imaging operations.

I would like to say that I believe Timo has contributed much careful thought and originality to what he is proposing here. People who are advanced enough in their knowledge of digital imaging would do well to examine what he says in detail. Timo has, at least in the past, been more than willing to respond individually to emails and I for one have found his ideas and discussions interesting and stimulating.

As for using a linear RGB space, Timo is correct. Almost all, if not all of the algorithms used in graphics are designed for linear RGB, and there are color fringing and other artifacts introduced because of the fact that we work in a non-linear gamma space. I believe there is much food for thought in that one assertion alone, and that is why I singled it out for consideration.
--
Mike Russell
www.curvemeister.com/forum/

"Mike Russell" wrote in message

wrote in message
...

Editing work in a non-linear RGB working-space will create such (and other) errors, editing work in the Lab space also does so. Editing work in the linear RGB space either completely avoids or at least minimizes all such errors.

I won't respond in detail to Timo's comments, if only because the topic has begun to stray from the original poster's concerns about changes in saturation due to interaction with other imaging operations.
I would like to say that I believe Timo has contributed much careful thought and originality to what he is proposing here. People who are advanced enough in their knowledge of digital imaging would do well to examine what he says in detail. Timo has, at least in the past, been more than willing to respond individually to emails and I for one have found his ideas and discussions interesting and stimulating.

As for using a linear RGB space, Timo is correct. Almost all, if not all of the algorithms used in graphics are designed for linear RGB, and there are color fringing and other artifacts introduced because of the fact that we work in a non-linear gamma space. I believe there is much food for thought in that one assertion alone, and that is why I singled it out for consideration.
--
Mike Russell
www.curvemeister.com/forum/

fwwwwooooooooomp
sound of words flying right over my head.............................

"KatWoman" wrote in message
....

fwwwwooooooooomp
sound of words flying right over my head.............................

LOL - my apologies. With a little bit of luck, a cat (une jolie chat princess) can duck!
--
Mike Russell
www.curvemeister.com/forum/

"Mike Russell" wrote in message

"KatWoman" wrote in message
...

fwwwwooooooooomp
sound of words flying right over my head.............................

LOL - my apologies. With a little bit of luck, a cat (une jolie chat princess) can duck!
--
Mike Russell
www.curvemeister.com/forum/

splat cat on da floor

I was an artist before any photo work (and came to that in the dinosaur time of film and paper, scraping silver off to retouch and using Doc martin dyes)

I use PS in a completey intuitive way, by looking at the results by my eyes I know all you techies like the scientific methods and explanations.

I dunno how my car works and I can't build one but I damn sure can put gas in and drive.

[re tech speak and cabbages and kings]

I was an artist before any photo work (and came to that in the dinosaur time of film and paper, scraping silver off to retouch and using Doc martin dyes)

I'm a Spot Tone man myself.

I use PS in a completey intuitive way, by looking at the results by my eyes
I know all you techies like the scientific methods and explanations.

I think both are important, but if the rubber never meets the road, in terms of actual examples and images, the science can actually be worse than useless. Case in point - all the money currently being spent on profiling equipment, and the over-hype about color gamuts.

I dunno how my car works and I can't build one but I damn sure can put gas in and drive.

That's all we ask, Katwoman. That, and more pictures. :-) ---
Mike Russell
www.curvemeister.com/forum/

KatWoman wrote:

I dunno how my car works and I can't build one
but I damn sure can put gas in and drive.

Unfortunately that alone does not make you a good, not to mention an excellent, driver, not in the normal traffic nor on the rally track.

I often relate the task of image editing with that of a surgeon ... it is not enough that the surgeon knows how to hold and operate a knife.

It is so with what ever task we perform, to know how to use a tool is just a very early beginning, in order to achive something good, something worth to mention, we do need to know a lot about the target itself and about the circumstances.

Naturally one can learn some tricks or "recipes" that one can, more or less blindly, apply in Photoshop over an image after another but it is the same as driving a car without knowing anything about traffic regulations/rules/code and knowing nothing about the behavour of the car in some more demanding situations, so absolutely disastreous.

In order to actually improve the images, to create something special, to invent new or to refine existing editing techniques, we simply must know, very deeply and in detail, the properites of those digital images that we are adjusting using the various tools and we need to know what are the properties that the tools affects to. And we need to know about the properties of the vision, the properties of various display and printing systems, about calibration and profiling. etc.

Timo Autiokari

wrote in message

KatWoman wrote:

I dunno how my car works and I can't build one
but I damn sure can put gas in and drive.

Unfortunately that alone does not make you a good, not to mention an excellent, driver, not in the normal traffic nor on the rally track.
I often relate the task of image editing with that of a surgeon ... it is not enough that the surgeon knows how to hold and operate a knife.
It is so with what ever task we perform, to know how to use a tool is just a very early beginning, in order to achive something good, something worth to mention, we do need to know a lot about the target itself and about the circumstances.

Naturally one can learn some tricks or "recipes" that one can, more or less blindly, apply in Photoshop over an image after another but it is the same as driving a car without knowing anything about traffic regulations/rules/code and knowing nothing about the behavour of the car in some more demanding situations, so absolutely disastreous.
In order to actually improve the images, to create something special, to invent new or to refine existing editing techniques, we simply must know, very deeply and in detail, the properites of those digital images that we are adjusting using the various tools and we need to know what are the properties that the tools affects to. And we need to know about the properties of the vision, the properties of various display and printing systems, about calibration and profiling. etc.

Timo Autiokari

timo you misunderstand me
I am a fan of knowing how to use the tools the best ways possible I just don't know how to make the tools
I could not program a single line of code to make a level adjustment tool I could not invent a program like Photoshop. I greatly admire those who do know these things and am grateful to them.
I am not advocating using poor PS techniques, I was trying to say that the OP does not have to know how saturation works to see what to do with the tool.
I am saying I am not a fan of what you call "recipes", doing PS by formulas or by the numbers for such as skin tones, I feel this is an artistic decision best made by the artist by looking. Images are a visual medium, the criteria is subjective. Those of us who have degrees in art do know the "rules" of design etc but also know much interesting art and innovation comes from breaking those same rules and how much good art can be made from "happy accidents".
In any case it is my own preferred method of creating. I know many photographers feel more comfortable with charts, numbers and scientific technical rules.
Image making is a blend of science and art, I was always a "messy" artist too. I like the organic explosion method of creation more than the controlled execution method of creation. (which I can also do when necessary)
In my formal art education I had a professor who taught us to get away from always coloring in the lines, in fact the students that kept at it flunked the class.
and PS I am a really good driver too
my husband was a race car driver and he taught me
he followed me to the mechanic shop last week and complimented my driving He also mentioned I have never once been in an accident (as the driver) )