Color by numbers

With the addition of RGB pins and the recent P1 tip of February 3rd I wanted to offer a a quick overview of using color by numbers to assure results at final output.

An easy and straightforward method is detailed in the blog. For the most part this will serve you well with the addition of a bit more info.Traditionally 240 and 20 have been the magic numbers for highlight and shadow detail when the final output is printed. With recent improvements in printing technology I feel it is safe to use 245 and 15 for the max and minimum values of highlight and shadow detail. Importantly it must be noted that these values represent the brightest and darkest areas in which we desire detail. It is OK, even desirable for some areas of a given image to read 255 or 0 if they do not hold detail relevant to the composition.

A neutral mid tone is always a great starting point. Either find or create one using a mid tone value in your image or a grey card. Many things are dead on neutral in practical terms tree bark, untreated wood that has been exposed to the elements, asphalt, and some concrete. The idea is to anchor the image to a neutral midpoint. It is not necessary for the midpoint to be absolutely 128 just close so we are certain that the middle of the image has a neutral color balance.

Highlight detail should be measured in non reflective areas, NO specular or reflective highlights. Specular and reflected highlights can be several times the highest RGB number of 255 in proportional terms so seeking detail in reflections will not set a correct highlight point for the rest of the image in most cases. If the object is to provide "correct" color as well as a full contrast range it is also important to find a neutral highlight point.

Shadow detail is measured in the area of the picture that contains the last shred of important detail on the low end. This is a highly subjective venture. There are no wrong answers and the idea is to develop a system so that you know what low end detail is important and what can be sacrificed in the name of a full range picture. Holding irrelevant shadow detail compresses the contrast range and prevents getting a true black value.

The idea of a skin tone pin is great but to really work well the pin should read values in CMYK. All human skin is in the red family so a pin that reads CMYK would allow precise control over the balance of skin tones. It is the blend of Y and M that gives us a realistic skin tone. In general for the fairest Caucasian skin the Y and M values should be equal or heavy a point or so to Y. Other skin tones go heavier to Y with the darkest African Skin tones reaching a value of +12-15Y.

Finally these are just general guidelines all photographic artists are free to bend these rules as they see fit. Knowing how this process affects your prints will make you a better image maker. I f you can create a dead on neutral color balance and full contrast range using the numbers it follows that you can swing your picture anyway you like to make a creative statement.