4 August 1993 Equidistant color series and color thresholds: printing of both by line-screen technique
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Properties of the visual system were described to produce on that basis colorimetric data for equidistant color series and color thresholds (just noticeable differences). There is a complex relationship between equidistant color series and color thresholds. The luminous reflectances for gray series were discussed for both equidistant color series of separated samples and color thresholds of touching samples. The threshold is very much dependent on viewing or adaptation time. Modern film recorders with 3600 lines per inch (lpi) allow dots or lines with 0.007 mm diameter. The high resolution allows line-screen exposure and printing of high stability with 225 lpi to fill the halftone cell of a square (0.1 mm X 0.1 mm) with 16 X 16 dots (or lines combined with dots). The luminous reflectance varies theoretically between 0 and 16 X 16 equals 256. This allows to produce only about 16 equidistant visual steps of separated samples on a gray surround between black and white for both dot and line- screen technique. Most difficulties with the stability appear near black. The stability of the printing process is increased using line-screens compared to dot screens. The dots vary in all directions during the printing process and the line width in only two directions. Four color printing with cyanblue, yellow, magentared and black can be based on line-screens with vertical, horizontal and two diagonal directions. Some properties are discussed using PostScript-programs and studying multicolor prints produced by line-screen technique.
© (1993) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Klaus Richter "Equidistant color series and color thresholds: printing of both by line-screen technique", Proc. SPIE 1909, Device-Independent Color Imaging and Imaging Systems Integration, (4 August 1993); doi: 10.1117/12.149084; https://doi.org/10.1117/12.149084

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