THotPDF.RenderColorimetricLuminosityMasks

Chooses how loaded-page rendering turns the colors of a luminosity soft mask into mask values

Declaration

property RenderColorimetricLuminosityMasks: boolean read FRenderColorimetricLuminosityMasks write FRenderColorimetricLuminosityMasks default false;

Remarks

When the property is false (the default), a luminosity mask weights the resolved red, green, and blue values of its group as 0.30, 0.59, and 0.11, whatever the blending space of the group. A mid-grey therefore masks about half, which is how common PDF viewers draw drop shadows and fades

When the property is true and the mask group has a CIE-based blending space (CalGray, CalRGB, Lab, or ICCBased), the mask takes the CIE 1931 Y component as ISO 32000-1 section 11.5.3 describes. Y is measured on a linear scale, so the same mid-grey masks only about a fifth and shadows come out lighter than in common viewers

Groups in device spaces are not affected. The /BC backdrop color of the mask is converted the same way as the paint inside the group

The setting participates in memory and disk render-cache identity, so bitmaps rendered under one setting are never returned for the other

Example

Doc.RenderColorimetricLuminosityMasks:= true;
Bitmap:= Doc.RenderLoadedPageToBitmap(0, 150);