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A BSTRACT
Halftoning methods can be divided into two main categories, namely AM (Amplitude Modulated) and
FM (Frequency Modulated). Some printing methods, such as Flexography, are not able to produce dots
small enough to handle the highlights and the shadows of the original image by just using AM
halftoning method. To overcome this problem FM method is used in the highlights (and the shadows)
and an AM method in rest of the image.
Hybrid halftoning (combination of AM and FM) technique for grayscale images has already be
presented showing the best way to place FM and AM dots in the resulting binary image. This thesis
work is and extension of that and presents hybrid technique for color images. In color images, besides
the problem of transition area between AM and FM, a number of other factors needs to be addressed.
One of such factors is to define the starting point of FM technique in different color channels. In this
work all the possibilities of combining AM and FM in different color channels have been investigated
and then the best approach for hybrid color halftoning is proposed. This approach not only uses the best
solution for starting point of FM halftoning in each channel but also places the different color dots in
the highlights, as homogenously as possible.
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