Specifications

Intel
®
Image Processing Library Reference Manual
2-4
2
Coordinate Systems
Two coordinate systems are supported by the library’s image format.
• The origin of the image is in the top left corner, the x values increase
from left to right, and y values increase from top to bottom.
• The origin of the image is in the bottom left corner, the x values
increase from left to right, and y values increase from the bottom to the
top.
Image Regions of Interest
A very important concept in the Image Processing Library architecture is
an image’s region of interest (ROI). All image processing functions can
operate not only on entire images but also on image regions.
Depending on the processing needs, the following image regions can be
specified:
• Channel of interest (COI). A COI can be one or all channels of the
image. By default, unless the COI is changed by the
SetROI()
function, processing will be carried out on all channels in the image.
• Rectangular region of interest (rectangular ROI). A rectangular
ROI is a portion of the image or, possibly, the entire image. By default,
unless changed by the
SetROI() function, the entire image is the
rectangular region of interest.
• Mask region of interest (mask ROI). It is specified by another
(bitonal) image pointed to by the
maskROI pointer of the IplImage
structure.
A mask ROI allows an application to determine on a pixel-by-pixel
basis whether to perform an operation. Pixels corresponding to zeros in
the mask are not read (if in a source image) or written (if in the
destination image). Pixels corresponding to 1’s in the mask are
processed normally.
The origin of the mask ROI is aligned to the origin of the rectangular
ROI if there is one, or the origin of the image.
An image can simultaneously have any combination of a rectangular ROI,
a mask ROI, and a COI. Operations are performed on the intersection of all