cc [ flag... ] file... –lmlib [ library... ] #include <mlib.h> mlib_status mlib_ImageHistogram2(mlib_s32 **histo, const mlib_image *img, const mlib_s32 *numBins, const mlib_s32 *lowValue, const mlib_s32 *highValue, mlib_s32 xStart, mlib_s32 yStart, mlib_s32 xPeriod, mlib_s32 yPeriod);
The mlib_ImageHistogram2() function creates a histogram by scanning an image, counting the number of pixels within a given range for each channel of the image, and then generating a histogram.
The image can have 1, 2, 3 or 4 channels. The data type of the image can be MLIB_BYTE, MLIB_SHORT, MLIB_USHORT, or MLIB_INT. The histogram must have the same number of channels as the image has.
One entry of the histogram, or a bin, is used to accumulate the number of pixels within a certain sub-range. The legal pixel range and the number of bins may be controlled separately.
If binWidth is defined as (highValue - lowValue )/numBins then bin i counts pixel values in the following range:
lowValue + i*binWidth ≤ x < lowValue + (i + 1)*binWidth
The set of pixels scanned may furthermore be reduced by specifying xPeriod and yPeriod parameters that specify the sampling rate along each axis.
The set of pixels to be accumulated 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
It is the user's responsibility to clear the histogram table before this function is called and to ensure that the histogram table supplied is suitable for the source image and the parameters. Otherwise, the result of this function is undefined.
The range from lowValue[k] to (highValue[k] - 1) must be a valid subrange of the image type range.
The function takes the following arguments:
Pointer to histogram. The format of the histogram is histo[channel][index]. The index values for channel i can be 0, 1, ..., numBins[i]-1.
Pointer to source image.
The number of bins for each channel of the image.
The lowest pixel value checked for each channel.
The highest pixel value checked for each channel. When counting the pixel values, highValue is not included.
The initial X sample coordinate.
The initial Y sample coordinate.
The X sampling rate. xPeriod ≥ 1.
The Y sampling rate. yPeriod ≥ 1.
The function returns MLIB_SUCCESS if successful. Otherwise it returns MLIB_FAILURE.
See attributes(5) for descriptions of the following attributes: