Within the Digital medium we are uniquely able to strip our paintings to their individual elements and benefit greatly from the analysis thereof. This article will focus on the isolation and analysis of one of these elements: Value.
Out of the three elements of Color previously defined here: Digital Color Primer, I feel that Value is often the most important, especially with regards to visual clarity of subject. An image with great color (Hue and Saturation) but poor Value is often unreadable, yet an image with great Value and poor color maintains legibility, indeed an image with only Value retains much of it's clarity and intent.
As with all guidelines, this is of course bendable and even breakable but in the day to day business of a visual communicator it's a guideline that is useful more often than not.
I've encountered and utilized a variety of methods to evaluate Value throughout the years and will now attempt to identify the best and the worst.
Look first at the chart below and ask, are there hues that appear greater in Value than others?
Squint your eyes if you haven't already and reevaluate. Squinting compresses the range of light available to the eye while maintaining an appropriate ratio of contrast thereby facilitating the comparison.
If you opened the above image with Photoshop and used the Color Picker you would notice that each hue occupies the same Saturation and Brightness coordinates, 100S and 100B. If you've read the previous article you'd remember, "In Photoshop, Brightness is a measure of the intensity of the RGB pixels on your screen. This is not an accurate measure of the intensity of light."
Yellow is obviously higher in value than Blue, yet removing Saturation will not represent this vital distinction
Desaturation as a method of Value analysis is unfortunately the most common by far and falls victim to the confusion between the terms Brightness and Value. You'll note above, each Hue's inherent Value disappears and with it any hope at an accurate analysis.
A Black and White adjustment layer is often presented as an alternative. Although there is a variety in Value with the default settings you'll see that this is oddly arbitrary. Although a customized setting may be able to achieve a more accurate representation it's far more cumbersome than elegant and therefore void of any persistent use
How can you judge accurately without Accuracy?
Converting an image to Grayscale is to my eyes quite a bit more accurate and as you can see Yellow is high in value and Blue rather low. The standard method for conversion however, (Menu>Image>Mode>Grayscale) is also rather cumbersome and more than a little distracting from the overall image-making process...
Note the Value discrepancies between Grayscale and a Black and White adjustment above and all methods below.
Fortunately there is an elegant method of achieving a more accurate Value analysis with only two keys, CTRL+Y, (the shortcut for Proof Colors). If you've tried it just now, chances are your image has shifted into the default CYMK colorspace and if you're like me you may have accidentally activated this shortcut in the past instead of Ctrl+T (Transform) and understandably been annoyed at the result. Once you've set up this tool as instructed below you'll find this annoying slip is your new, if sometimes unexpected, ally.