Merge pull request #103 from yamt/otsu
Fix possible overflows in otsu()
This commit is contained in:
commit
c6fc67088a
1 changed files with 8 additions and 8 deletions
|
@ -177,28 +177,28 @@ static void flood_fill_seed(struct quirc *q, int x, int y, int from, int to,
|
||||||
|
|
||||||
static uint8_t otsu(const struct quirc *q)
|
static uint8_t otsu(const struct quirc *q)
|
||||||
{
|
{
|
||||||
int numPixels = q->w * q->h;
|
unsigned int numPixels = q->w * q->h;
|
||||||
|
|
||||||
// Calculate histogram
|
// Calculate histogram
|
||||||
unsigned int histogram[UINT8_MAX + 1];
|
unsigned int histogram[UINT8_MAX + 1];
|
||||||
(void)memset(histogram, 0, sizeof(histogram));
|
(void)memset(histogram, 0, sizeof(histogram));
|
||||||
uint8_t* ptr = q->image;
|
uint8_t* ptr = q->image;
|
||||||
int length = numPixels;
|
unsigned int length = numPixels;
|
||||||
while (length--) {
|
while (length--) {
|
||||||
uint8_t value = *ptr++;
|
uint8_t value = *ptr++;
|
||||||
histogram[value]++;
|
histogram[value]++;
|
||||||
}
|
}
|
||||||
|
|
||||||
// Calculate weighted sum of histogram values
|
// Calculate weighted sum of histogram values
|
||||||
unsigned int sum = 0;
|
double sum = 0;
|
||||||
unsigned int i = 0;
|
unsigned int i = 0;
|
||||||
for (i = 0; i <= UINT8_MAX; ++i) {
|
for (i = 0; i <= UINT8_MAX; ++i) {
|
||||||
sum += i * histogram[i];
|
sum += i * histogram[i];
|
||||||
}
|
}
|
||||||
|
|
||||||
// Compute threshold
|
// Compute threshold
|
||||||
int sumB = 0;
|
double sumB = 0;
|
||||||
int q1 = 0;
|
unsigned int q1 = 0;
|
||||||
double max = 0;
|
double max = 0;
|
||||||
uint8_t threshold = 0;
|
uint8_t threshold = 0;
|
||||||
for (i = 0; i <= UINT8_MAX; ++i) {
|
for (i = 0; i <= UINT8_MAX; ++i) {
|
||||||
|
@ -208,13 +208,13 @@ static uint8_t otsu(const struct quirc *q)
|
||||||
continue;
|
continue;
|
||||||
|
|
||||||
// Weighted foreground
|
// Weighted foreground
|
||||||
const int q2 = numPixels - q1;
|
const unsigned int q2 = numPixels - q1;
|
||||||
if (q2 == 0)
|
if (q2 == 0)
|
||||||
break;
|
break;
|
||||||
|
|
||||||
sumB += i * histogram[i];
|
sumB += i * histogram[i];
|
||||||
const double m1 = (double)sumB / q1;
|
const double m1 = sumB / q1;
|
||||||
const double m2 = ((double)sum - sumB) / q2;
|
const double m2 = (sum - sumB) / q2;
|
||||||
const double m1m2 = m1 - m2;
|
const double m1m2 = m1 - m2;
|
||||||
const double variance = m1m2 * m1m2 * q1 * q2;
|
const double variance = m1m2 * m1m2 * q1 * q2;
|
||||||
if (variance >= max) {
|
if (variance >= max) {
|
||||||
|
|
Loading…
Reference in a new issue