Color Basics Part 8 – Image Editing
A neglected aspect of color management is the fact that a scanner profile alone is not enough to optimize all original images. As in traditional color separation, every image is unique and needs its own adjustment to compensate for exposure or development differences. Add to this the limitations imposed by gamut compression and the need to override technology for creative reasons, and it is easy to understand why there is a demand for skilled operators in a color-managed workflow.
When an image needs adjustment, ICC-based, color editing software is used in place of the scanner’s software. These programs simulate the look and feel of scanner software but take full advantage of ICC device profiles. A main advantage of ICC-based software is that, while editing, the operator sees an accurate image on the computer monitor, or “Soft Proof,” that simulates the final print. Soft proofing allows visual confirmation of corrections, which simplifies training and operation while allowing more powerful correction of sub-standard originals. It also helps minimize re-makes and reduce editing times.
Good ICC-editing software lets the user select from a list of input and output profiles to suit the origin and destination of each image. Operation is easy to learn, but quality results and productivity depend on the operator’s training and experience.
A major difficulty for operators is that many controls work in different modes: RGB (red, green and blue), or LCH (lightness, chroma and hue) rather than CMYK (cyan, magenta, yellow and black). When a CMYK output device is chosen, CMYK changes are allowed (or at least a CMYK dot percentage readout is available) even when making RGB or LCH changes. One big advantage to working in LCH instead of CMYK is that, although it takes an adjustment, any LCH value will look the same no matter what device or profile is selected. Once the visual meaning is learned, LCH means the same thing no matter what new input or output device is introduced. No longer do you have to memorize the different CMYK values for each device. LCH is universal, or device-independent, which is the whole point of color management.
Control of each element in that color reproduction process, often referred to as process control, is the fourth key element to implementing color management. Each process component, including scanner, monitor, proofer, imagesetter, processor, and the printing press, must be managed to that the variation associated with each of these components is predictable. A color management profile requires predictability because it assumes that the color gamut capability of a device remains constant. An unpredictable process renders a color management profile useless and ineffective.
In this series, we explored color from many angles. We looked at what it is, how nature creates it, and how nature and we can recreate it. The understanding of color and the limitations of the reproduction process (whichever is used) is key to accomplishing an end product that is pleasing to the customer, the client, the end viewer, and every person along the process that contributes to the project. I hope that this series was informative, and maybe even sparked a different way we look at apples.