So What's So Different About Digital?
Not As Much As You'd Think!
TEXT AND IMAGES BY BOB DINATALEChoosing your color space will affect the personality of your image.
As a professional photographer moving into digital, you've
already acquired the basics for optimizing digital images in
theconventional photography realm. You just need to understand
their application in the digital world.
As the photons of light hit the silver emulsion or CCD chip, there are many areas where digital photography is not very different from wet photography. In this article, I'll cover some of the essentials by illustrating the similarities—rather than the differences—between digital and conventional photography.
Color Channels, Film's Color Layers
Color film has three light-sensitive silver halide channels or layers: R,G,B. B&W film generally has one panchromatic layer. Color files from our scanners or digital cameras have the same RGB channels, while a B&W file needs only one luminance channel. The difference here is that within the same format, the physical size of the color and B&W films is the same, while a digital B&W file can be one-third the size of an RGB file.
Color Depth: More Colors,
Not Greater COLOR Range
The difference between 24-bit color and 30-bit color is
a difference of either 256 or 1,000 shades in each color channel—not more color range, but more gradations within the same range. Do we need that many colors? It helps. More gradations provide more information, which means more detail. This info has a greater effect on the toe (shadows) and shoulder (highlights) detail and less on the straight part of the S-curve. Ansel, wherever you are, I know you're watching!
Different Color Spaces, Different Film
Different "color spaces" have different gamuts, which translate into different ranges of colors, not necessarily more colors. With most color models (RGB, CMYK), different color spaces produce the same color with different color values. Said another way, different color spaces have different colors with the same color values!
Are you with me? O.K. In wet photography, have you ever photographed a red barn on two different color films at the same time? The two films produced different red barns from the same Sherman Williams paint—read "same color value." We say that these films have different "personalities" or different color spaces.
Positive Films Expose for the Highlights
Although the exposure range of the CCD is not as great as film's, it's getting there. Sometimes we just can't fit the entire brightness range of the scene on the CCD "film." Besides using tried-and-true photo techniques like "fill-in flash" or white reflectors, treat your digital exposure as you would any positive film: expose for the highlights.
Pushing Film UPS Grain, Pushing ISO UPs
As one would expect, the ISO values of films and CCD chips are similar. In conventional photography, when taking pictures in low light, we get better results using a higher ISO film than pushing development of a slower film. Pushing film development increases grain. In digital photography, when we use different ISOs, we don't change CCD chips. The camera selects a higher ISO and "pushes" the signal. Pushing the signal increases the noise.
Another Generation, Another Degradation
Allow me to state the obvious: you can get better prints if you have better processing techniques. But am I talking about digital or conventional photography? Yes.
If your client liked a print on your wall and wanted a copy, you wouldn't send the print to the lab, have the lab make a negative from the print, then a final print from the negative—especially since you have the original negative.
If someone saw the resultant print on your client's wall and asked for a copy, it would be foolish to make another generation (read "degradation") by taking that print off the wall, sending it to the lab, having the lab make another negative from the "copy print," and then making another print from that negative!
We know the image degradation caused in the above example. Yet this is how we process our digital files. We adjust for contrast then "click" to process the pixels. Then we adjust for color then "click," re-processing the same pixels (read "second generation"). Then we select another area, maybe a shadow that needs lightening, "click"—another re-process, then adjust for contrast, more color correction, brightness. "Click," "click," "click" . . . re-reprocessing our pixels for a third, fourth, and fifth time (read "generation" or "degradation"—your choice). You get the picture.