mlib_ImagePolynomialWarp(3mediaLib Library Funcmlib_ImagePolynomialWarp(3MLIB)NAMEmlib_ImagePolynomialWarp - polynomial-based image warp
SYNOPSIS
cc [ flag... ] file... -lmlib [ library... ]
#include <mlib.h>
mlib_status mlib_ImagePolynomialWarp(mlib_image *dst,
const mlib_image *src, const mlib_d64 *xCoeffs,
const mlib_d64 *yCoeffs, mlib_s32 n, mlib_d64 preShiftX,
mlib_d64 preShiftY, mlib_d64 postShiftX, mlib_d64 postShiftY,
mlib_d64 preScaleX, mlib_d64 preScaleY, mlib_d64 postScaleX,
mlib_d64 postScaleY, mlib_filter filter, mlib_edge edge);
DESCRIPTION
The mlib_ImagePolynomialWarp() function performs a polynomial-based
image warp.
The images must have the same type, and the same number of channels.
The images can have 1, 2, 3, or 4 channels. The data type of the images
can be MLIB_BYTE, MLIB_SHORT, MLIB_USHORT, or MLIB_INT. The source and
destination images may have different sizes.
The xCoeffs and yCoeffs parameters must contain the same number of
coefficients of the form (n + 1)(n + 2)/2 for some n, where n is the
degree power of the polynomial. The coefficients, in order, are associ‐
ated with the terms:
1, x, y, x**2, x*y, y**2, ...,
x**n, x**(n-1)*y, ..., x*y**(n-1), y**n
and coefficients of value 0 cannot be omitted.
The image pixels are assumed to be centered at .5 coordinate points. In
other words, the upper-left corner pixel of an image is located at
(0.5, 0.5).
For each pixel in the destination image, its center point D is backward
mapped to a point S in the source image. Then the source pixels with
their centers surrounding point S are selected to do one of the inter‐
polations specified by the filter parameter to generate the pixel value
for point D.
The mapping is defined by the two bivariate polynomial functions X(x,
y) and Y(x, y) that map destination (x, y) coordinates to source X and
Y positions respectively.
The functions X(x, y) and Y(x, y) are:
preX = (x + preShiftX)*preScaleX
preY = (y + preShiftY)*preScaleY
n i
warpedX = SUM {SUM {xCoeffs_ij * preX**(i-j) * preY**j}}
i=0 j=0
n i
warpedY = SUM {SUM {yCoeffs_ij * preX**(i-j) * preY**j}}
i=0 j=0
X(x, y) = warpedX*postScaleX - postShiftX
Y(x, y) = warpedY*postScaleY - postShiftY
The destination (x, y) coordinates are pre-shifted by (preShiftX,
preShiftY) and pre-scaled by the factors preScaleX and preScaleY prior
to the evaluation of the polynomial. The results of the polynomial
evaluations are scaled by postScaleX and postScaleY, and then shifted
by (-postShiftX, -postShiftY) to produce the source pixel coordinates.
This process allows for better precision of the results and supports
tiled images.
PARAMETERS
The function takes the following arguments:
dst Pointer to destination image.
src Pointer to source image.
xCoeffs Destination to source transform coefficients for the X
coordinate.
yCoeffs Destination to source transform coefficients for the Y
coordinate.
n Degree power of the polynomial.
preShiftX Displacement to apply to destination X positions.
preShiftY Displacement to apply to destination Y positions.
postShiftX Displacement to apply to source X positions.
postShiftY Displacement to apply to source Y positions.
preScaleX Scale factor to apply to destination X positions.
preScaleY Scale factor to apply to destination Y positions.
postScaleX Scale factor to apply to source X positions.
postScaleY Scale factor to apply to source Y positions.
filter Type of resampling filter. It can be one of the follow‐
ing:
MLIB_NEAREST
MLIB_BILINEAR
MLIB_BICUBIC
MLIB_BICUBIC2
edge Type of edge condition. It can be one of the following:
MLIB_EDGE_DST_NO_WRITE
MLIB_EDGE_SRC_PADDED
RETURN VALUES
The function returns MLIB_SUCCESS if successful. Otherwise it returns
MLIB_FAILURE.
ATTRIBUTES
See attributes(5) for descriptions of the following attributes:
┌─────────────────────────────┬─────────────────────────────┐
│ ATTRIBUTE TYPE │ ATTRIBUTE VALUE │
├─────────────────────────────┼─────────────────────────────┤
│Interface Stability │Committed │
├─────────────────────────────┼─────────────────────────────┤
│MT-Level │MT-Safe │
└─────────────────────────────┴─────────────────────────────┘
SEE ALSOmlib_ImagePolynomialWarp_Fp(3MLIB), mlib_ImagePolynomialWarpT‐
able(3MLIB), mlib_ImagePolynomialWarpTable_Fp(3MLIB), attributes(5)SunOS 5.10 2 Mar 2007 mlib_ImagePolynomialWarp(3MLIB)
