Photographic Images

Unlike computer-generated graphics, images are the result of sampled raster data and seamlessly combine the quality elements of graphics, tints, and blends. Because of the wide range of potential subject matter in an image, a printer’s ability to produce realistic, high-quality images is extremely difficult, but critical to the user’s quality perception—even if only at the time of product selection. Therefore, a printer must produce high quality images.

The use of photographic data sources for images leads to a high demand for color fidelity. This includes accurate reproduction of memory colors—those with which users are heuristically familiar—without requiring an original for comparison. Natural greens, sky blues, wood browns, and skin tones represent common memory colors that can tax a printer’s color rendering ability due to color gamut restrictions, imprecise color balance, or sub-optimal colorants. Another demand for image color fidelity is matching a color-corrected photograph such as a calibrated image file with an associated profile or in a standardized color space such as sRGB or SWOP. Although sometimes causing conflict, both objectives are important.

High-contrast, high spatial frequency detail within an image reflects a printer’s ability to provide high quality text and graphics. The device resolution is used to carry the high level of fine detail. In areas of little variation (low spatial frequency), process noise and screen artifacts (in the case of non-continuous-tone printers) can be readily apparent. Finally, smoothly varying regions require blend linearity in order to accurately capture the realistic appearance and visual depth of the original.

• Photo Print Quality Focus Groups

  Again, we can measure how accurately individual colors are reproduced, but determining which prints people prefer, and why, are elusive, subjective judgments. Photo Print Quality cannot be completely analyzed by purely objective means; while we can measure how accurately individual colors are reproduced, determining which prints people prefer—and why—are elusive judgments, inherently subjective.

  Augmenting our standards for the objective measurement of photographic print quality, we have accumulated extensive experience in worldwide managment of Photo Print Quality Focus Groups.