A comparative study was made of random dot printing and conventional halftone printing with respect to color characteristics. Random dot printing is similar to continuous tone printing or very high frequency screen ruling and is capable of overcoming the limitatio of halftone printing. The randomly selected dots are achieved by the grain structure of the pre- sensitized printing plates. The advantages and the disadvantages of this process over conventional halftone printing process are discussed. The images and the test targets of both the processes were exposed to, and printed from a single plate for each process color so as to eliminate the ink and press variables. The experimental steps and the criteria for the plate exposure and processing have been discussed. The design of the flat and a copy of the reproduction are also included. For the purpose of objective evaluation of the color characteristics tone reproduction of both the processes and of each process color were studied. The hue error introduced by two different processes were measured. The proportionality of unwanted densities with the wanted density for each process color were derived and curves were plotted. Further, the attributes of colors, such as lightness or brightness, saturation and dominant wavelength (hue) were compared by plotting the chromaticity diagram (eIE 1931). The chromaticity diagrams were plotted for two different standard light sources and the results were discussed. For a better representation of the data an enlarged chromaticity diagram was used. The results may be interpreted to show that the random dot process allows a larger color gamut, produce brighter colors and shows less proportionality failure.
Department, Program, or Center
School of Photographic Arts and Sciences (CIAS)
Hazra, Sanat, "A comparison of the random dot and the conventional halftone printing process with respect to color characteristics" (1981). Thesis. Rochester Institute of Technology. Accessed from
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