Mean
Computes the mean of image pixel values. For multi-channel images, the mean is calculated over each channel and saved in the corresponding channel array.
The function interface declaration is as follows:
HmppResult HMPPI_Mean_8u_C3R(const uint8_t *src, int32_t srcStep, HmppiSize roiSize, double mean[3]);
HmppResult HMPPI_Mean_8u_C4R(const uint8_t *src, int32_t srcStep, HmppiSize roiSize, double mean[4]);
Parameters
Parameter |
Description |
Value Range |
Input/Output |
|---|---|---|---|
src |
Pointer to the source image ROI |
The value cannot be NULL. |
Input |
srcStep |
Distance between starts of consecutive lines in the source image, in bytes |
The value must be zero or a positive integer. |
Input |
roiSize |
Size of the ROI of the source and destination images, in pixels |
roiSize.width ∈ (0, INT_MAX], roiSize.height ∈ (0, INT_MAX] |
Input |
mean[] |
Array for storing the mean values for each channel of the source image (multi-channel scenario) |
Value range of the pixel data type of the source image |
Input/Output |
Return Value
- Success: HMPP_STS_NO_ERR
- Failure: An error code is returned.
Error Codes
Error Code |
Description |
|---|---|
HMPP_STS_NULL_PTR_ERR |
The value of src is NULL. |
HMPP_STS_SIZE_ERR |
The width or height of roiSize is zero or negative. |
HMPP_STS_STEP_ERR |
The value of srcStep is zero or negative. |
HMPP_STS_NOT_EVEN_STEP_ERR |
The value of srcStep cannot be exactly divided by the byte length of the data type to which src belongs. |
HMPP_STS_ROI_ERR |
The value of roiSize.width is greater than the step. |
HMPP_STS_COI_ERR |
The value of coi is not 1, 2, or 3. |
Example
void MeanExample()
{
HmppiSize roi = {3, 4};
uint8_t src[9 * 4] = {1, 1, 1, 2, 2, 2, 3, 3, 3,
4, 4, 4, 5, 5, 5, 6, 6, 6,
7, 7, 7, 8, 8, 8, 9, 9, 9,
10, 10, 10, 11, 11, 11, 12, 12, 12};
int32_t srcStep =9*sizeof(uint8_t);
double mean[3] = {0.0};
int32_t i;
HmppResult result =HMPPI_Mean_8u_C3R(src, srcStep, roi, mean);
printf("result = %d\n", result);
if (result != HMPP_STS_NO_ERR) {
return;
}
for(i =0; i <3; i++) {
printf("%lf ", mean[i]);
}
printf("\n");
}
Output:
result = 0 6.500000 6.500000 6.500000