Monday, December 13, 2010

Gray Matter

If you can make a picture with two values only, you have a strong and powerful picture.
  If you use three values, it is still good, but if you use four or more, throw it away.
-Howard Pyle

When examining the tonal plan of my reference - whether it is a photograph or a live model - I frequently forget that what I am looking at is not an absolute whose values I must match exactly in my painting, but rather a guide for plotting value relationships.  Too often, I have been a slave to my reference, when I should have intelligently manipulated the values I was observing in order to make a better picture.

In his book, Creative Illustration, Andrew Loomis explains that there are specific relationships between the areas of shadow and light in a subject which are dependent upon the intensity of the illumination source.  He expresses these relationships between light and shadow using the steps of the value scale, which, in his system, consists of eight equidistant tones ranging from White (1) to Black (8).  As example, Loomis proposes that the separation between light and shadow on a subject in full sunlight would, in general, be three tones (reflected light in the shadows will lighten those dark areas, but the region of shadow closest to the light- sometimes called the 'bedbug line' -will maintain the separation of tones Loomis describes).  The top value and bottom value in this parameter are unimportant, provided that the separation remains consistent.  It is much the same as a single piano tune being played in multiple key signatures;  the song remains the same, provided the notes keep their proper relationship.

It must be noted here that what Loomis is discussing when he talks about tone is not the value of the local color of the subject, but the effect of light and shadow on the local color.  So if a red shirt in neutral light were a value of 4 on Loomis' scale (in other words, its local color tone), in full sunlight it might appear to the eye to be a value of 3 in the light, and a value 6 in the shadow.

Once the value relationship in your subject is understood, Loomis demonstrates that that particular information can be altered to present multiple interpretations of the same scene.  In each representation in Loomis' example above, the tone separation remains constant throughout, though in some of his studies the local tone of certain objects were altered for effect.  In this way, a composition can be strengthened through the simplification of value patterns (what James Gurney refers to as "Shape Welding"), without sacrificing a believable lighting situation.

Being able to accurately translate values from a live model to the canvas takes a certain amount of trial and error at first, but it becomes easier with practice.  To then be able to transpose the visible values while working from life, however, takes a greater familiarity and understanding of the intensities of light Loomis describes.  Again, this ability comes only after experience, and much observation.

I was reminded of this skill several years ago while watching an alla prima demonstration given by Jeremy Lipking at the California Art Institute.  Lipking seems to prefer working under natural lighting conditions, but that day, his model was lit by a hot, incandescent lamp.  When he began his painting, I was surprised to see the value he selected for the light areas on the model's white gown.  To me, being very accustomed to working under such conditions, the value of the gown in the lights appeared to be an 8 on the Munsell scale (In the Munsell System, there are 11 equidistant tones ranging from Black - 0, to White - 10).  Lipking instead chose a 5 or 6, which I imagined he would have to correct as the painting progressed.  But as he continued, it became apparent that Lipking was altering all of the values, keeping them in a tighter, more compressed range of tones.  With his experience working from life, Lipking had manipulated the value relationships he saw before him to paint a subject which, to all appearances, had been posed in diffused light, his favored lighting condition.  The end result was a painting imbued with a character and mood which would not have been present had Lipking merely copied the values in the scene before him.

In this painting by Jeremy Lipking, the lighting is diffused, much like the gray lighting preferred by the Naturalists.
The darkest value in the picture is a 2 on the Munsell scale;  the lightest, an 8.  On the model, the brightest area
 of skin is a 6; the darkest (other than the deepest folds) is a 3.

Though I cannot overemphasize the importance of learning to assess values when working from life, if you are only able to work from photographs, you at least have more objective tools for identifying tones in your reference.  The most common and effective way to understand the values in a photograph is to simply reduce the photo's color data to a black and white using computer software.  The translation is a simple process, but there are some tricks which can make the resulting information even easier to understand.

The most important tool in deciphering tonal values is the value scale;  this is why I append a pre-made scale to any color photograph I intend to translate into black and white so I can have that gauge always nearby.  Since I use the Munsell system, my value scale, which I created in Photoshop, contains 11 tones  ranging from white to black.

To make the scale, I began with a new image file in Photoshop, 1 inch high and 11 inches long, and with a background color of 'white.'  This I then divided into 11 squares using guides.  I approached each tone square as if this were a screen printing project, choosing to think of each section as a percentage of 'black' (ie. Value 9, which is 90% white, can also be thought of as 10% black.  Value 8 would be 20% black; value 7, 30% black; and so on...).  One by one, each square was then selected, and filled using the color black and the Paintbucket tool.  This action, however, was done each time on a separate layer, which was later merged with the background.  The separate layers were necessary, because each successive layer had a different fill percentage in order to control the density of black in each square (eg.  The layer which represented value 8, had a fill percentage of only 20%).

I realize this sounds complicated, but it is really very simple, and hopefully, a logical construction method.  Of course, there are many ways to reach the same end result, and mine is only one route to reach the objective.  The easiest method now would be to just download my scale, providing you subscribe to Munsell's classification of values, and if that helps, then please do so.

A photograph of yours truly.  The image on the right has had the color information discarded by converting the image to B&W
 using the Grayscale mode.

Once I have the scale added to my photograph, I convert the image to black and white by changing the file's color mode to 'Grayscale.'  (From the Photoshop menu, choose ImageModeGrayscale and then agree to discard the color information).  Some people advocate using desaturate to remove the color information from a photo, but that would be a mistake.  When you desaturate an image, the luminance of the original colors is not preserved.  This is most apparent in yellows and greens, which appear brighter to the human eye;  when the luminance is not preserved, these colors will appear much darker in the desaturated image. The Grayscale image is a much more accurate reflection of the values we would regularly perceive.

This painting by Andrew Loomis is flanked by the same image Desaturated on the left, and converted to Grayscale on the right.  Notice how the yellow leaf disappears in the Desaturated image.

The reason why someone would choose to use Desaturate over changing the Mode to Grayscale when converting a photo to black and white is probably because of the advantages gained by having the file in RGB.  One such advantage is that black and white images print better in color modes-  the values tend to be more subtle and have smoother transitions.  Another advantage is for the people who like working from monochromatic images rather than black and white images.  These people will add an overall color to the black and white picture in order to shift the picture to a more pleasant hue.  (From Photoshop menu, Image→Adjustments→Variations).  Off course, there is an easy remedy to this when you have an image in Grayscale mode;  simply change the mode back to RGB after discarding the color information (Image→Mode→RGB Color), and you will have regained all of the advantages of the color channel.

Options available in the Variations tab.

Once you have your Grayscale reference, you have another useful tool at your disposal:  Posterization.  In Photoshop, the Posterize command (Image→Adjustments→Posterize) allows you to separate your image into a finite number of tone separations.  The number of separations is up to you, but if you are using the Munsell system, you would choose 11 levels of distinct tones (any additional tones would be averaged into the nearest respective value on the scale).  Using Loomis's scale, you would divide the image into 8 levels;  for Pyle, you might use 3 or 4 levels.  And this is where it is important that you have added a value scale to your photograph at the beginning;  posterization divides the images into the number of levels you indicate using the extremities of tone in the reference for parameters.  If your darkest dark in your photograph were actually a value 3 on the Munsell, and the lightest light was an 8, the posterize command would set those as the end points, and create the other separations between those two extremes.  By adding the image of the scale, values 0 and 10 (black and white respectively) will become the extreme tones when you execute Posterize.

From left to right:  Original, 11 levels, 8 levels, and 4 levels.
Notice how the value scale also compresses when the levels are reduced.  In the far right image, values 0, 1, 2, and 3 have all been averaged to the same tone (Black).

On a Mac, another tool at your disposal is the Digital Color Meter application.  After the image has been posterized, the Meter can be used to verify values.  Simply roll the cursor over one of the posterized zones in the image, note the RGB statistics, and find the matching statistics when you roll the cursor over your value scale.  This will give you the exact value of that section of your reference.

The Digital Color Meter is registering the color of the cheek just to the right of my nostril.
When checked against the value scale, it matches a value 6 in the Munsell System.

Using these tools can be helpful in understanding value, and in finding a better way with which to work with tones to create better compositions.  However, breaking down each of your own works this way can also be a bit stifling, and has the possibility of taking some joy out of painting.  Perhaps the best way to employ these tools is to use them to analyze Master works which you find most satisfying.  Assimilate  those lessons and apply them to your own paintings until they become a regular part of your arsenal;  this will then give you the freedom to intelligently design the tone pattern in your work, and do so with confidence.

In this painting of the Pieta by William Bouguereau (1876), the artist uses the full range of value at his disposal.
  Even on the figure of Christ, Bouguereau used a broad range of tone.  The brightest lights on the skin are a 9;
the deepest shadow on His body, a 2.  Christ's loin cloth contains pure white (10), and Mary's robe, which
surrounds Christ's outline and separates the Two from the background, is black (0).


Stephen Southerland said...

A valuable reminder. The importance of values cannot be stressed enough. I believe I have some more studying to do.

Mick Carney said...

A thought provoking piece with vital lessons for us all. Once again thanks are necessary for the very valuable advice that you share with us.

Tayete said...

Clap, clap, clap, clap...An always complex (and interesting) matter, very well analyzed.

Thanks a lot for this wonderful post!

*Tayete runs to try to put in practice some of what he has learnt right now*

willek said...

Thoughtfully and thoroughly presented. Thanks

Savlen said...

Jeremy just today I was making a folder of masterworks broken down into 3 value studies using desaturate and posterize. Just tried your method and although Im grumbling as Im deleting the folder that I put so much time into, your absolutely right and what a difference. thank you for this very informative and interesting post. It really hit home today.

Cathyann said...

Thank you very much, Matthew. Clear, concise and a very appropiate tool was used to illustrate your thoughts and suggestions.

Savlen said...

Matthew please accept my humblest apologies for putting the wrong name down when I commented yesterday. In my defense I was exhausted after painting for 12 hours and my brain was a little fried. At any rate excellent article and very informative. Thank you

Cindy Pickup said...

Thanks, such great info. I'm a student, and this is just what I needed, at just the right time. Thanks!

Kyle T. Webster said...

Thank you for this excellent post!

Munell said...

Wonderful walk-through!
People sometimes forget the weight that tonal value carries in a gray-scale piece. Expression and color communication are intrinsically linked, but value importance in B & W work can not be ignored. Looking forward to your next post!!

Vincent Nappi said...

thanks so much for this awesome post. looks like desaturating is out, and grey scaling is in!

JonInFrance said...

Great post!. I would have thought that for the accurasee grid tool, that it would be better as a training aid if, instead of a regular grid you could drag lines to the main (horizontal and vertical) alignments you want to use... ... just a thought... could mebbe use some diagonal lines too... hmm

Irina said...

Thank you very much. So useful.

Nebu said...

hey, thanks a lot for posting this piece. Learnt quite a lot from it.

Cozinha da Pintura said...
This comment has been removed by the author.
Kristin Forbes-Mullane said...

Great post!

YlarTassan said...

yes, I think values are "the" most important part about painting. After you get everything in the right place it's time to experiment with the values.

Jane E Porter said...

Thank you so much, your article is really helpful. Janee

sharon weeks said...

This has helped me more than anything I have found. I have no painting background and have been trying to find useful information for 2 months.
I an glad I can finally use my PSP for more than an ico on my desk top.

Thank you.