Dan Margulis Applied Color Theory

Where Is the Neutral Gray?

   Date: Mon, 3 May 2004 11:01:34 -0400
   From: Fred Yocum
Subject: So what is/where is the neutral gray?

I have Dan's books. I've even read  and reread them!
One thing I have continued to struggle to get my head around is finding the neutral gray. As a designer who has come from a fine art background I am trained not to see neutral colour. When I look at photograph I can cope with finding the white point and the black point.  I can even cope with moving the flesh tints to the right place but where do I find a neutral grey? I have posted a photograph I have recently needed to colour correct. You can find the low resolution of the raw scan here, I'll leave it up for a couple of days:

http://www.mcc.org/temp/mcc_temp.jpg

This is a photograph with plenty of white things in it (and some extreme darks as well ). Where should I be find for the neutral grey. The back of the shirt? The kitchen cabinet door? The light switch on the wall? The back wall? Each of those areas has a colour cast which makes it non-neutral and each is different.

F D Yocum
Graphic Designer
Mennonite Central Committee
___________________________________________________________________________

   Date: Mon, 03 May 2004 09:15:29 -0600
   From:Andrew Rodney
Subject: Re: So what is/where is the neutral gray?

What1s the colorspace? There is no way to give you specific neutral values numerically unless the document is in a well behaved RGB working space like Adobe RGB 1998, ColorMatch RGB etc. These spaces all produce a neutral when R=G=B. Any other color space (input or output), all bets are off. There are no special, specific CMYK or RGB values that are neutral that you can depend on when the color space is an input or output space. Close maybe, but then you have to know what output device you're aiming for.

Andrew Rodney
http://www.digitaldog.net
___________________________________________________________________________

   Date: Mon, 03 May 2004 15:30:31 -0000
   From: Stephen Marsh
Subject: Re: So what is/where is the neutral gray?

Andrew, I think that Fred's question is more from a colour correction point of view. Let's presume that he has this tagged in a working space...and is simply asking where should he click his neutral eyedropper or where to place a colour sampler and then to manually edit the curves/levels as he does when setting endpoints.

Fred,

***IF*** the 'white' shirt is really white and not 'off white - cream, yellow or some other minor tint' which should be kept...then, yes - the mid value shadow point on the shirt (somewhere) would be a good choice, as shading on white should be neutral to the human eye, but perhaps not to a capture device...

What I would do before editing, is to assign the correct profile for the work to be done and then to run the mouse/info palette over the image and read values and place fixed samplers...as well as visual evaluation.

What are the existing values? What colour does this make? Is it natural or required? What happens to other colours and tones if global edits are applied? Is the result good or bad? These and many more questions will be asked as you make global and selective edits.

Hope this helps,

Stephen Marsh.
___________________________________________________________________________

   Date: Mon, 03 May 2004 11:37:24 -0400
   From: Jim Rich
Subject: Re: So what is/where is the neutral gray?

Fred,

Neutral gray is seen in a range from light to dark. That is a white tones (like a highlight area) are typically neutral gray. And the black tones (the extreme shadows) are considered neutral gray. The gray tones in between are the neutral gray midtone areas of the image.

As for finding a neutral gray midtone. Well... that is really your choice based on your knowledge of the original, the photograph, the scan and what the client wants to see.

If you want the the kitchen cabinet door or  the light switch on the wall or the back wall to be neutral gray you have the tools in Photoshop to do make those areas exactly neutral. But if you  took the time to do that, my sense is the image reproduction would look fake.

So the solution is find a compromise as to what you want the image to look like. The compromise is to  target images areas such as kitchen cabinet door etc that are not going to be exactly neutral gray and to find some compromise between neutral and the color cast of the original. And if you don1t like the original then you might consider making some subjective color adjustments to make the reproduction look more pleasing.

Jim Rich
___________________________________________________________________________

   Date: Mon, 3 May 2004 12:08:09 -0400
   From: Fred Yocum
Subject: Re: Re: So what is/where is the neutral gray?

You are right, perhaps I should have worded differently -- I was really looking for strategy in deciding where on an image to call neutral grey.

Andrew, I think that Fred's question is more from a colour correction
point of view.

It sounds like it is trial and error in that you choose a place on the image that could be neutral and see what it does to the image as a whole?

Should the process be:
1)  adjust for white point and black point,
2)  decide on a point to adjust to neutral gray
3) Amend that point if it throws values in important areas into an
unacceptable place. (makes the flesh tones too blue etc)
___________________________________________________________________________

   Date: Mon, 03 May 2004 09:51:02 -0600
   From:Andrew Rodney
Subject: Re So what is/where is the neutral gray?

on 5/3/04 9:30 AM, Stephen Marsh wrote:

Andrew, I think that Fred's question is more from a colour correction
point of view.

No doubt but are we talking about making this neutral via numbers of color appearance or both?

Let's presume that he has this tagged in a working
space...and is simply asking where should he click his neutral
eyedropper or where to place a colour sampler and then to manually
edit the curves/levels as he does when setting endpoints.

Well it's pretty obvious in this case where he clicks a neutral eyedropper will produce a neutral and he'll have to view with the info palette how all the other values update. What is the right location to click? The area he wants neutral of course.

What are the existing values? What colour does this make? Is it
natural or required? What happens to other colours and tones if
global edits are applied? Is the result good or bad? These and many
more questions will be asked as you make global and selective edits.

Exactly, there's no right answer unless we know that something in the scene is supposed to be neutral and the effect everywhere else is less important. But my original point which I think might not be clearly understood by all is that in order for us to get a neutral value numerically, we need to be in a color space that provides a behavior where using the set neutral eye dropper will indeed produce a neutral.

Andrew
___________________________________________________________________________

   Date: Mon, 03 May 2004 13:19:30 -0400
   From: Lee Clawson
Subject: Re: So what is/where is the neutral gray?

...Where should I be find for the neutral grey. The back of
the shirt? The kitchen cabinet door? The light switch on the wall? The
back wall?...

Any of the items you mention could be used to check for neutral. The background seems to have the warmest cast. First thing I'd ask is does it visually distract from the intent of the image?

Start with an output profile or knowing how the printer inks make gray. Usually I look for an area just under the middle gray as an "aim" and look at how it effects other areas (to help see the tone range compare it to a grayscale). In this specific photo I'd be concerned with getting neutral at the cost of good skin color, not something I'd want.

Are you getting this cast (often) in a digital camera or scanner? If so, the "fix" should take place there.

Lee
___________________________________________________________________________

   Date: Mon, 03 May 2004 13:21:14 -0400
   From: Jim Rich
Subject: Re: Re: So what is/where is the neutral gray?

On 5/3/04 12:08 PM, "Fred D Yocum"wrote:

It sounds like it is trial and error in that you choose a place on the
image that could be neutral and see what it does to the image as a whole?
Should the process be:
1)  adjust for white point and black point,
2)  decide on a point to adjust to neutral gray
3) Amend that point if it throws values in important areas into an
unacceptable place. (makes the flesh tones too blue etc)

Fred,

Your proposed order is a good place to start for correcting an image if you only want to use Curves or Levels.

After doing those types of adjustments you would want to consider using tools like Hue & Sat then Selective color in that order. I am not saying to make colors brighter or more saturated, but to use these selective color options to make specific colors less bright or more toward neutral gray.

Then if you still were not there you would want to consider some type of masking techniques to isolate a image area.

Jim Rich
___________________________________________________________________________

   Date: Mon, 3 May 2004 12:46:16 -0700
   From: "Mike Russell"
Subject: Re: So what is/where is the neutral gray?

Fred,

Yes, there is gold in Dan's books.

Your example is an interesting one because, as you say, it has many potential neutrals.  The question of a neutral gray is an eternal one, and I often find myself feeling around the image for a "sweet spot" that, when selected as the neutral, will give the image a pleasing overall cast - usually I try for an overall neutral to slightly warm look to the image.

Overall, the image is a mixed lighting battleground between blues and yellows, with bluish daylight coming in from the right, and warmer lighting from the interior of the building.  The image is underexposed, and as is usual with underexposed images, it lacks color saturation.

To address saturation and brightness issues, I chose to do this correction in Lab mode.

For this image, I got the best results by choosing the bowl in the front corner of the disk rack as a neutral.  The cabinet front is too yellow to use as a neutral, due either to its actual color or reflected light from the interior of the room.  The wall under the counter is a good contender for the neutral as well.  I would bet a nickel that the electrical outlet on the wall is ivory colored.  Normally a stainless steel sink or other brushed metal object  is a no-brainer neutral, but here it's too blue, probably because it's lit by sky, and selecting it in this case gives the entire image an unacceptable yellow cast.  As it is, I compromised and left the sink looking like it's made of blue porcelain.

As often happens with digital camera images and scans, the highlight and shadow cover the entire dynamic range, but an S-shaped Lightness curve is needed to perk up detail in the face and hands, without totally blowing out the shirt.  And overall color saturation needs to be cranked up, without sending the wood trim on the cabinet doors into hyper-saturated limbo.

The final image and the Lab curves used to correct it are at www.geigy.2y.net/tmp/mcc_tmp.html.  I used Curvemeister to more easily generate the curves, but the curve files themselves are Photoshop compatible.

With your permission, I'd like to add your image as an example to my "Misfortunate Images" tutorial at: http: //www.curvemeister.com/tutorials/misfortunate/ .

Mike Russell
www.curvemeister.com
www.geigy.2y.net
___________________________________________________________________________
   
Date: Mon, 3 May 2004 14:08:07 -0400
   From: Fred Yocum
Subject: So what is/where is the neutral gray?

Are you getting this cast (often) in a digital camera or scanner? If so, the
"fix" should take place there.

The motive for the question was more general. In Dan's books he writes about finding an area that should be a neutral gray and moving the image to reflect that as a way of correcting the colour. This photograph seemed to be a excellent example because it has a enormous range of white things which could or should be neutral. From my fine art background nothing is neutral -- ala Monet and Pissaro and from the postings so far I take it that finding a neutral point is subjective and provisional. Find area that might be neutral, make it neutral and see what happens to the rest of the photograph?
___________________________________________________________________________

   Date: Mon, 03 May 2004 19:20:03 -0400
   From: Dolores Kaufman
Subject: Re: So what is/where is the neutral gray?

Fred, the way I see it the only color cast in this picture that is important is the yellow cast on the subject, most notably on the white shirt. Since we 'know' the shirt is white, any shading in that  white is expected to be 'neutral'. So, there would be two good reasons to concentrate on the shirt: the subject is wearing it and we 'know' it is white. In this case, we don't really care about the color of the cabinets or the dishes.

I opened up your image in Photoshop and opened up a Selective Color adjustment layer. I selected 'neutrals' and moved the slider to minus 5%. I find this is a simple and straigtforward way to deal with color casts because if you remove a color cast from the 'neutrals' you remove it from the entire picture. I also like what it did to the subject's skin. It gave it a slightly bluer, less muddy appearance. If you find that the removal is too much for any other areas or colors then just create a mask on the adjustment layer and paint it out where you want. You can paint out at any percentage up to 100%. Like you I come from a fine art background and like painting on adjustment layers. It's very intuitive and gives you a lot of control. If you really wanted to get fancy you could create an adjustment layer for each color cast and simply paint it in where you want it (select the mask, fill with black, paint with white). Hope this helps.

Dolores
___________________________________________________________________________

   Date: Tue, 4 May 2004 11:26:09 EDT
   From: Dan Margulis
Subject: Re: So what is/where is the neutral gray?

Fred Yokum writes,

I have Dan's books. I've even read and reread them!
One thing I have continued to struggle to get my head around is finding
the neutral gray.  

Philosophically this is the wrong approach. You don't look for "the" neutral gray, because a) it may not exist at all and b) if you find one, it's not "the" gray--you have to look for another one.

It's a little like looking for a fleshtone. If you've got a picture of a forest, it would plainly be crazy to insist that there is a fleshtone in there somewhere and to force some poor tree to be a skintone value. Forcing some object that may or may not be neutral to become gray is almost as bad.

In the picture you've supplied, there happen to be a whole slew of such known-neutral colors. There's an African-American man whose hair is surely black. There's a pot cover and a metallic sink. The wall beneath the cabinet is neutral by inference because, as Mike Russell points out, the outlet cover is almost certainly ivory and the wall next to it is significantly less yellow. And there's a coffee cup in the background that's also black by inference. I don't think we can conclude that the dishes are white, or the shirt either, for that matter.

Under ordinary circumstances you would have to make sure that *all* of these items were neutral, not just one. The problem here is that the image has at least two and probably three conflicting casts. When that happens, you usually need a selection. Here, the obvious problem is that the man's face is more blue, less yellow than the cabinet behind it which is of the same darkness. That can't possibly be right, but if you change it, it is just as much a move away from the art as if you had decided to make his hair orange. The version that Mike made with LAB curves is much better than the original, but the face is blue, not the desaturated red it should be, and the hair is cyan.

FWIW, if I were doing it I would load an inverted version of the red channel as a mask and knock the blue cast out of the background with RGB curves. Then, with the overall color more sensible, I would do what Mike did and increase the saturation in the A and B channels. Still, there would be some color retouching work to be done because the face, although red, wouldn't be red enough.

This is the kind of image that I use in my *advanced* class--it's too hard for the basic ACT curriculum. Although an expert can get good results out of multiple-cast originals like this, you shouldn't take it as a typical example. Curves without selections work in the vast majority of all cases--this just happens to be the exception.

Dan Margulis
___________________________________________________________________________

   Date: Tue, 4 May 2004 11:13:04 -0400
   From: Fred D Yocum
Subject: Re: So what is/where is the neutral gray?

Thank you Mike, your response is exactly what I was looking and gives me a clear understanding of what strategies to use. It was most helpful. I had looked at curvemeister earlier and was chagrined to see that it is not available for mac ,  the environmentin which I work. Curves are where I spend most of my time in PhotoShop and I can use all the help I can get.

Adobe Photoshop training classes are taught in the US by Sterling Ledet & Associates, Inc.