Halftone phase operators

This page applies to Harlequin v13.1r0 and later; both Harlequin Core and Harlequin MultiRIP.

sethalftonephase

x y sethalftonephase

sets the halftone phase parameters in the graphics state. x and y are integers specifying the new halftone phase, defining an offset from the device space origin to the halftone origin. One halftone cell somewhere on the page has its origin (lower left corner) placed at pixel coordinates (x , y) on the output raster (whose origin is also at the lower left).

Therefore, to achieve a centering on a page, x and y are required to be pixel addresses of the page center (this is clearly resolution and page size dependent). The default halftone phase is (0, 0), though any call to setpagedevice  changes this according to page size.

currenthalftonephase

currenthalftonephase x y

Pushes the current halftone phase parameters in the graphics state onto the operand stack.