Operators Dialog / Operator Details

§ 12.11.41 - Halftone

Scripting command: halftone [dither=0...1] [cropedge=0...1] [threshold=1...254] [gamma=0...100] [DMethod=0...7]

Note: All available scripting operations are listed on the Script operator page.

The halftone operator

Thresholds an image into bilevel black and white.

Gamma is provided to compensate for the change in apparent brightness and contrast that occurs when halftoning is performed. A setting of 1.0 results in no gamma change; less than 1.0 and the halftoning will trend darker; more than 1.0 and the halftoning will trend brighter. A Gamma setting of .47 results in a reasonably linear compensation for the halftone dot gain, and so is generally suggested.

Tip: Gamma is applied only within the area selection, so for area selections that do not include the entire image and have anti-aliased edges, a Gamma transition occurs at the boundary that can show up in the thresholded result. This can be avoided by setting Gamma to 1.0 and applying gamma separately to the entire image using the Gamma operator prior to halftoning, or by turning off anti-aliasing for the area selection in use.

If  Dither is checked, then Floyd-Steinberg, or Jarvis, Judice, and Ninke, or one of five detail levels of ordered dithering, depending on the setting of  DMethod    is used to create the bilevel result. If it is not, then the image is thresholded against the value set by Threshold

Tip: Floyd-Steinberg dithering results in slightly more defined edges, while Jarvis, Judice, and Ninke dithering results in slightly better rendered smooth transitions. Typically, it's best to try both and then pick the result you like better. The differences may be subtle.

If  Edge Crop is checked, then the outer image edge of Floyd-Steinberg dithering is set to black to hide the partial error propagation; generally, this looks better. If the region being modified is entirely within the image, this has no effect.

 Source    allows you to choose what monochrome interpretation is made of the image prior to halftoning.

Caution: The image must be at least 5 or more pixels wide and high to be halftoned.
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