(v13) InterpolateAllImages, InterpolateAllMasks (user param)

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

Note: PDF 2.0 8.9.5.3 mentions the image dictionary entry /Interpolate bool, which is a hint to PDF consumers that an image should be interpolated. Our /InterpolateAlImages setting controls whether this hint is used to turn on image filtering, or whether image filtering is forced on or off. Image filtering can be up-sampling by interpolation (that is, when image resolution is too low) or down-sampling by averaging (when image resolution is too high). If either filter is enabled, it is used to resample an image to match output resolution unless the image is already at that resolution.

The /InterpolateAllImages and /InterpolateAllMasks user parameters are four-state values, which are set with a simple name, one of DefaultTrue , DefaultFalse , ForceTrue , ForceFalse .

To turn interpolation on for all images, you would use:

<</InterpolateAllImages /ForceTrue>> setuserparams

To turn image interpolation on for only those images which specify /Interpolate true in an image dictionary, you would use:

<</InterpolateAllImages /DefaultFalse>> setuserparams

The default value of both of these user parameters is ForceFalse , meaning that image and mask interpolation is disabled by default. This is a change from previous behavior, which was effectively the same as DefaultFalse , meaning that any image or mask which specified /Interpolate true would be interpolated.

The previous value of true maps to ForceTrue , and the previous value of false maps to

DefaultFalse .

There are two changes from the previous implementation of image interpolation:

1. Interpolation is now off by default.
2. The user parameters InterpolateAllImages and InterpolateAllMasks now provide a more complete control over image filtering although the previous behavior is still supported.

Default: ForceFalse .