General Linear Filters
These functions use a general rectangular kernel to
filter an image. The kernel is a matrix of signed integers or single-precision
real values. For each input pixel, the kernel is placed on the image in such a
way that the fixed anchor cell within the kernel coincides with the input
pixel. The anchor cell is usually a geometric center of the kernel, but can be
skewed with respect to the geometric center.
A pointer to an array of kernel values is passed to
filtering functions. These values are read in row-major order starting from the
top left corner. This array must exactly have
kernelSize.width
*
kernelSize.height
entries.
The anchor cell is specified by its coordinates
anchor.x
and
anchor.y
in
the coordinate system associated with the lower right corner of the kernel.
The output value is computed as a sum of neighbor
pixels values, with kernel matrix elements used as weight factors. Summation
formulas implement a convolution operation, which means that kernel
coefficients are used in direct order.
Optionally, the output pixel values may be scaled. To ensure valid
operation when image boundary pixels are processed, the application should
correctly define additional border pixels (see
Borders in Neighborhood Operations
).
In Intel IPP 8.2 and lower versions, kernel coefficients are used in
inverse order.