mlib_ImageExtremaLocationsmediaLib Library Fumlib_ImageExtremaLocations(3MLIB)NAME
mlib_ImageExtremaLocations, mlib_ImageExtremaLocations_Fp - image
extrema and their locations
SYNOPSIS
cc [ flag... ] file... -lmlib [ library... ]
#include <mlib.h>
mlib_status mlib_ImageExtremaLocations( mlib_s32 *min, mlib_s32 *max,
const mlib_image *img, mlib_s32 xStart, mlib_s32 yStart,
mlib_s32 xPeriod, mlib_s32 yPeriod, mlib_s32 saveLocations,
mlib_s32 maxRuns, mlib_s32 *minCounts, mlib_s32 *maxCounts,
mlib_s32 **minLocations, mlib_s32 **maxLocations, mlib_s32 len);
mlib_status mlib_ImageExtremaLocations_Fp( mlib_d64 *min, mlib_d64 *max,
const mlib_image *img, mlib_s32 xStart, mlib_s32 yStart,
mlib_s32 xPeriod, mlib_s32 yPeriod, mlib_s32 saveLocations,
mlib_s32 maxRuns, mlib_s32 *minCounts, mlib_s32 *maxCounts,
mlib_s32 **minLocations, mlib_s32 **maxLocations, mlib_s32 len);
DESCRIPTION
Each of the functions finds the image-wise minimum and maximum pixel
values for each channel, and optionally, their locations.
Each of the functions scans an image, finds the minimum and maximum
pixel values for each channel, and finds the locations of those pixels
with the minimum or maximum values.
The user provides initial minimum/maximum values through the arguments
min and max. This function will update them based on findings.
The set of pixels scanned may furthermore be reduced by specifying xPe‐
riod and yPeriod parameters that specify the sampling rate along each
axis.
The set of pixels to be scanned may be obtained from the following
equation:
x = xStart + p*xPeriod; 0 ≤ p < (w - xStart)/xPeriod
y = yStart + q*yPeriod; 0 ≤ q < (h - yStart)/yPeriod
The locations of the minimum/maximum, if asked, are recorded in a for‐
mat of run-length coding. Each run-length code, or simply called a run,
has a format of (xStart, yStart, length). Here length is defined on the
low-resolution image (with downsampling factors of 1/xPeriod, 1/yPer‐
iod) and does not cross rows. So the run-length code (xStart, yStart,
length) means that the pixels at (xStart, yStart), (xStart + xPeriod,
yStart), ..., (xStart + (length - 1)*xPeriod, yStart) of the original
image have a value of the minimum/maximum.
The buffers for minLocations and maxLocations are organized in the fol‐
lowing format for each channel i:
minLocations[i][0] = xStart0; // the 1st run
minLocations[i][1] = yStart0;
minLocations[i][2] = length0;
minLocations[i][3] = xStart1; // the 2nd run
minLocations[i][4] = yStart1;
minLocations[i][5] = length1;
...... // more runs
minLocations[i][len-1] = ...;
It is the user's responsibility to allocate enough memory for the buf‐
fers for minLocations and maxLocations. This function may return
MLIB_OUTOFRANGE, if any of the buffers is not big enough.
PARAMETERS
The function takes the following arguments:
min Pointer to the minimum values.
max Pointer to the maximum values.
img Pointer to the input image.
xStart Initial X sample coordinate.
yStart Initial Y sample coordinate.
xPeriod X sampling rate. xPeriod ≥ 1.
yPeriod Y sampling rate. yPeriod ≥ 1.
saveLocations If true (i.e., saveLocations != 0), find the extrema
locations; otherwise only find the extrema.
maxRuns Number of runs of the minimum/maximum the caller
expects for each channel. maxRuns ≥ 1. If it is
MLIB_S32_MAX, all the minimum/maximum locations should
be recorded.
minCounts Pointer to the numbers of runs of the minimum recorded
in minLocations.
maxCounts Pointer to the numbers of runs of the maximum recorded
in maxLocations.
minLocations Pointer to the minimum locations in a format of run-
length coding.
maxLocations Pointer to the maximum locations in a format of run-
length coding.
len Length of the buffers for the minimum/maximum loca‐
tions in each channel.
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_ImageExtrema2(3MLIB), mlib_ImageMaximum(3MLIB), mlib_ImageMaxi‐
mum_Fp(3MLIB), mlib_ImageMinimum(3MLIB), mlib_ImageMinimum_Fp(3MLIB),
attributes(5)SunOS 5.10 2 Mar 2007 mlib_ImageExtremaLocations(3MLIB)
