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Overprint, knockout or trapping in XPS?

Just wondering out overprint/knockout would be handled in XPS.

That is, black text with a cyan background might be overprinted to deal with registration problems. In PDF files, the text object has the attribute of whether it knocks out or overprints.
I am not finding a similar setting in the XPS spec.

Trapping is another issue, but does not need to be specified in the document.

AnthonyOpsDE

Knockout: by default, XPS uses the painters model, where existing pixels are replaced with pixels from the object rendered on top of it (at least for opaque content). That means, that for black text on top of any background the black text pixels simply replace the background pixels.

There are two possible mechanisms to control behavior deviating from this default:

a) Use of Markup extensions would allow a per-element level control of a custom attribute specifying knockout behavior

b) Custom PrintTicket features could be introduced to control this type of behavior

Other than that, the current XPS specification does not provide a standardized solution, other than some control for black generation and undercolor removal via the PrintTicket (section 8.5).

Trapping could also be specified by a custom PrintTicket feature, but similar to knockout control, this custom feature would not be standardized by the specification.

Oliver Foehr

Thank you for this info.

The "painters model" term is a bit misleading, as far as a name goes, becuase if I first paint a whole area with, say, light yellow, then I draw text with solid/opaque black, even though I should only see the black, there is still yellow paint under

AnthonyOpsDE

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