High quality color images with continuous ink jets

The halftone method used generates shades of color by controlling the number of ink drops deposited in each pixel. Since only about 22 drops are actually available during the time allowed for the printing of one pixel (25 ms), only 22 density steps plus white can be generated. The diffuse reflection density is shown as a function of the number of drops deposited in each pixel. The curve was obtained using cyan ink on baryte paper and depends on many parameters, especially paper quality. The 23 density steps obtainable by the halftone method will give rise to contouring which degrades image quality. This is especially true at the lowest density levels, where, e.g. the step between zero and one drop per pixel is very noticeable. The problem can be solved by using a variation of an error diffusion or dither algorithm.<>