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Skin Tone. Neutral Target Sample Image.

Eddie Gonzalez , Dec 26, 2005; 11:43 a.m.

Other than the image most folks know about...the one with the four children at the bottom and the hand holding the martini shaker, where can I download an image file that can be used as a target for neutral skin tones. If you find yourself wanting to talk about color profiles, color space, digital, computers, monitors, printers, etcetera, then I didn't do a good job at asking my question....and I appologize for that. I'm trying to adjust the colors in photoshop CS2 such that the ratio of RGB values are close to what happens in the real world naturally, rather than in the wonderful world of photography. Computers and digital equipment have nothing to do with the real thing. This has nothing to do with personal taste. If you took ideal balanced white light (eg. from the sun) and measured the ratio of RGB values reflected from the face of 50 average white skin caucasians, you would obtain the numbers I'm looking for. For example, it may be something like; R/G=1.28, R/B=1.55, G/B=1.20. Remember, this has nothing to do with photography, cameras, computers, digital, color space, nothing of the sort. These are ratios that existed two thousand years ago. While every caucasian in that group of fifty has diferent ratios, the average number will not vary by anything to speak of. If you took two diferent groups of 50 you might get a tiny variance where one group might have a R/G ratio of 1.28 and the other might be 1.27. The measurement is taken from a reading of how much red/Green/Blue is reflected off of the face/skin of fifty caucasians in balanced white light. Sorry to get off track...back to the main question of this post. Do you know of a target image of skin-tones that is recognized by the photographer comunity or can be regarded as a standard that other images can be compared against when it comes to skin-tones being neutral.

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Andrew Rodney , Dec 26, 2005; 11:52 a.m.

Sorry but this all has to do with color spaces and numbers and the fact that the human visional system doesn?t work anything like the way a digital camera or computer encoding system works.

Until you define the color space, we can?t even start to talk about numeric values.

Edward Ingold , Dec 26, 2005; 01:54 p.m.

You can probably come close in this quest using one of several Color Checker charts by Gretag-MacBeth. The charts come with an RGB reflectance scale, and have from two to a dozen so-called "standard" flesh tints.

From your description, you seem to want the numbers, not necessarily a chart or image file, so that you can adjust an image "by the numbers" to achieve a perfect balance around flesh tones.

Press operators have used "standard" ratios for flesh tones for years, in lieu of an objective method. Of course, different inks, papers, humidity, process temperatures (on and on) have an effect. Then again, which face or part of a face would you sample to set the "perfect" color balance. Any one face might have a dozen "shades", multiplied by the number of faces to balance. I've seen the numbers, but I don't remember what or when. The practicality of their use is too low to commit to memory, for obvious reasons.

The ultimate "average" color is neutral grey. That's not such a bad way to set the mid-range color balance, if you have something in an image, either a test chart or by serendipity, to measure. Invent any RGB number you want, just make them all the same.

The practical solution (other than a grey card) is to use one of the Color Checker charts to create a profile. That gives you linearity over a range of colors, with an emphasis on flesh tones. But you won't do that - what do I know?

Tim Lookingbill , Dec 26, 2005; 02:18 p.m.

Eddie,

There was a holy grail sort of target depicting the perfect fleshtones and its corresponding print made by Kodak for wedding photographers I came across a while back in another forum. But when I saw the linked digital image of what the poster considered perfect fleshtones, I gave up on the pursuit. It depicted a wedding couple with way too maroonish/magenta-ish looking fleshtones for my tastes. And this target/print was expensive as well.

There is no such thing as a neutral fleshtone because of all the varying changing conditions involved with human perception of color and neutrality. The four children PDI target you mentioned, I use only to check white point calibration for the appearance of varying levels of yellow which can be seen in all fleshtones no matter the lighting conditions, gender or race unless the subject is covered in pancaked makeup. I'm a pasty caucasion and I still see some yellow in bright daylight in my own fleshtone.

The gases in some artificial lights bouncing off at certain angles as it enters the lens like in flash units at close range can in some instances throw off camera sensors into reducing this yellow (by adding too much blue) where you end up with the magenta-ish fleshtone. I've seen this on some Nikon sample images on the web. Check the tutorial on skintone correction on LonestarDigital.com to see what I mean.

This site shows how even when using Auto white balance and applying neutral RGB numbers to white can throw off skintone:

http://www.sphoto.com/techinfo/rawconverters/pages/whitebalan ce2.htm.......Take the space out between n & c in the word balance.

In short just go for what looks good on a properly calibrated neutral looking monitor.

Eddie Gonzalez , Dec 26, 2005; 04:42 p.m.

My appologies again, Andrew. Two thousand years ago, before color space was invented, light had a property that made it reflectable by the skin on a white mans face. Even back then, the light which was being reflected off of the skin contained a specific ratio of Red to Green as well as other colors. This ratio does not depend on the subjective eye of the human. These ratios varied from person to person and even from forehead to nose to cheek of the same person. Another thing that existed long before computers and color spaces is an average of this ratio found in white faces. So if a tree falls in a forest and no one is there to hear it, does it make a sound? Well, if no one is looking at you, does your face reflect light? And if no one is looking at you and no one takes a picture, does this light which is being reflected by your face have a specific ratio of colors?

Eddie Gonzalez , Dec 26, 2005; 04:44 p.m.

Maybe I should not use the word neutral because maybe the color of skin is not neutral. If I understand the word neutral, it would be equal amounts of R/G/B, right?

Dennis Price , Dec 26, 2005; 05:32 p.m.

"...If I understand the word neutral, it would be equal amounts of R/G/B, right?..."

No, not always. As previous posters have discussed, it's not that simple.

Just as a test, create a Photoshop image with equal amounts of RGB, and compare how it looks on different monitors (side by side), printed on different inkjet and laser printers, as well as offset.

Something tells me all those "neutrals" will look different.

Tim Lookingbill , Dec 26, 2005; 05:46 p.m.

What's neutral? Color scientists have been grappling with this for years as I've found out from this wikipedia page:

http://en.wikipedia.org/wiki/White_point

I just got hooked on wikipedia yesterday. This site is like a magnet of info surprisingly quite a bit plumbed from the web. How reliable that is anyone's guess.

Andrew Rodney , Dec 26, 2005; 05:58 p.m.

> My appologies again, Andrew. Two thousand years ago, before color space was > invented, light had a property that made it reflectable by the skin on a white > mans face.

Color perception is a phenomena that happens in our brain.

I'm not sure what your point is and I'm not sure what you're looking for here.

Computers can only handle 1 and zeros. If you are asking for some numeric values that define a color, you are going to have to provide the color space you want those numbers in. Numbers along do not provide enough information to define a color appearance. That is why R255 is not the same in Adobe RGB (1998) as sRGB or any other color space.

I am not sure how to provide you a color ratio without numbers! And I certainly can not provide you anything that is defined on a computer without numbers. That is all they understand. Lastly, the human visual system as I said does not operate in a linear fashion thankfully or our heads would explode when we went from a dimly Lite room to full sunlight.

Edward Ingold , Dec 26, 2005; 06:55 p.m.

The H7 patch on a Color Checker SG chart looks like a "normal" Caucasian skin tone to me. Your mileage may vary - and there are 13 other "skin tone" patches to choose from. The RGB reflectivity for the H7 patch is 201/145/126 respectively on a scale of 0 to 256. The source of illumination is D50 (5000K) and the acceptance angle is 2 degrees. On the same chart and same illumination, neutral grey is 111/111/111 (within a few tenths).

This begs the question - what is red/green/blue? Certainly not discrete wavelengths, but each is a band of wavelengths with a certain distribution. One would expect peaks and valleys in both the source and reflectivity, especially reflectivity of a biological nature. My Eye One Pro takes 41 measurements from 380nm to 730nm in 10nm increments.

Forget the Empiricist kaka about forests, trees and perception.


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