Class: Vips::DemandStyle

Inherits:
Object
  • Object
show all
Defined in:
lib/vips/demandstyle.rb

Overview

Operations can hint to the VIPS image IO system about the kind of demand geometry they prefer.

These demand styles are given below in order of increasing restrictiveness. When demanding output from a pipeline, vips_image_generate() will use the most restrictive of the styles requested by the operations in the pipeline.

  • ‘:thinstrip` — This operation would like to output strips the width of the image and a few pels high. This is option suitable for point-to-point operations, such as those in the arithmetic package.

    This option is only efficient for cases where each output pel depends upon the pel in the corresponding position in the input image.

  • ‘:fatstrip` — This operation would like to output strips

    the width of the image and as high as possible. This option is 
suitable for area operations which do not violently transform 
coordinates, such as vips_conv().

  • ‘:smalltile` — This is the most general demand format.

    Output is demanded in small (around 100x100 pel) sections. This style 
works reasonably efficiently, even for bizzare operations like 45 
degree rotate.

  • ‘:any` — This image is not being demand-read from a disc

    file (even indirectly) so any demand style is OK. It's used for 
things like vips_black() where the pixels are calculated.