Multiple rectangular regions can be specified in
roi operation of
cv-calc (like the
draw operation), so that:
- everything outside these regions in the input images is set to zero, or
- these regions are cropped out of input images into separate images (the arguments prefixed to input will be removed).
All images in the input stream must have same number of regions. Any region with zero width or height (e.g. 0,0,0,0) will be ignored and, if needed, can be used so that all images have same number of regions.
If all the bounding boxes for an image have zero area, then the whole image will be set to zero