kdu_codestream::get_subsampling

Retrieves the canvas sub-sampling factors for this image component. The interpretation of the component index is affected by the component range arguments, first_component and max_components, supplied in any call to the apply_input_restrictions function. Also, the sub-sampling factors are affected by the transpose argument supplied in any call to the change_appearance member function.

The sub-sampling factors identify the separation between the notional centres of the component samples on the high resolution code-stream canvas. Since component dimensions are affected by discarding resolution levels, but this has no impact on the high resolution canvas coordinate system, the sub-sampling factors returned by this function are corrected (shifted up) to accommodate the effects of discarded resolution levels, as specified in any call to apply_input_restrictions.

comp_idx [int]

subs [kdu_coords &]