jpx_roi [struct]

For rectangular regions ( is_elliptical=false) this member holds the actual region of interest. Otherwise, it describes the bounding box of an elliptical region of interest whose major and minor axes are aligned with the horizontal and vertical cardinal axes.

Note that regions are defined only for code-streams, not any other image entities which may be found within a JPX file such as compositing layers or a composited image.

Note also that the region is expressed relative to the upper left hand corner of the image as it appears on the relevant code-stream's high resolution grid.

If true, the region member identifes the bounding box of an elliptical region whose maxor and minor axes correspond to the width and height (or vice-versa) of that bounding box.

If true, the region described here has actually been encoded as a prioritized ROI within the code-streams with which it is associated. JPEG2000 Part 1 code-streams may encode ROI's only using the MAXSHIFT method, also known as the implicit method. JPEG2000 Part 2 code-streams may use explicit ROI coding. If this member is false, the ROI is a semantic entity, described only at the level of the file format.

Indicates the coding priority for use in transcoding images which contain code-stream ROI's — i.e., ROI's for which is_encoded is true.