The descriptor field further describes the data associated with the operation. It may contain implied parameters and/or indicate additional required parameters.
To minimize the number of code branches in the function and thus reduce potentially unnecessary execution overhead, most of the general functions are split into separate primitive functions, with some of their parameters entering the primitive function name as descriptors.
However, where the number of permutations of the function becomes large and unreasonable, some functions may still have parameters that determine internal operation (for example, ippiThreshold).
The following descriptors are used in image and video processing functions:
Image data contains an alpha channel as the last channel, requires C4, alpha-channel is not processed
Image data contains an alpha channel as the first channel, requires C4, alpha-channel is not processed
Image data is made up of n discrete interleaved channels (1, 2, 3, 4)
Channel of interest (COI) is used in the operation
Image is two-dimensional
Operation is performed in-place (default is not-in-place)
Operation uses a mask to determine pixels to be processed
Image data is made up of n discrete planar (non-interleaved) channels, with a separate pointer to each plane
Function operates on a defined region of interest (ROI) for each source image
Saturation and fixed scaling mode is used
Saturation and no scaling
The abbreviations of descriptors in function names are always presented in alphabetical order.
Not all functions have every abbreviation listed above. For example, in-place mode makes no sense for a copy operation.
Some data descriptors are implied when dealing with some operations. For example, the default for image processing functions is to operate on a two-dimensional image and to saturate the results without scaling them. In these cases, the function name does not contain the implied abbreviations D2 (two-dimensional data) and s (saturation and no scaling).
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