void imCalcPercentMinMax(const imImage* image, float percent, int ignore_zero, int *min, int *max)
{
int zero = -imHistogramShift(image->data_type);
int hcount;
unsigned long* histo = imHistogramNew(image->data_type, &hcount);
imCalcGrayHistogram(image, histo, 0);
unsigned long acum, cut = (unsigned long)((image->count * percent) / 100.0f);
acum = 0;
for (*min = 0; *min < hcount; (*min)++)
{
if (ignore_zero)
{
if (*min != zero)
{
acum += histo[*min];
if (acum > cut)
break;
}
}
else
{
acum += histo[*min];
if (acum > cut)
break;
}
}
acum = 0;
for (*max = hcount-1; *max > 0; (*max)--)
{
acum += histo[*max];
if (acum > cut)
break;
}
if (*min >= *max)
{
*min = 0;
*max = hcount-1;
}
*min += imHistogramShift(image->data_type);
*max += imHistogramShift(image->data_type);
imHistogramRelease(histo);
}
int imProcessBrinkThreshold(const imImage* image, imImage* dest, bool white_is_255 )
{
imImage *src = imImageDuplicate( image );
if ( !white_is_255 )
imProcessNegative( src, src );
int i, j;
int Topt = 0;
double p[MAX_GRAY]; // pmf (i.e. normalized histogram)
unsigned long histo[MAX_GRAY]; // from imlib: "Histogram is always 256 positions long"
double m_f[MAX_GRAY]; // first foreground moment
double m_b[MAX_GRAY]; // first background moment
double tmp0[MAX_GRAY][MAX_GRAY];
double tmp1[MAX_GRAY][MAX_GRAY];
double tmp3[MAX_GRAY][MAX_GRAY];
double tmp4[MAX_GRAY][MAX_GRAY];
double tmpVec1[MAX_GRAY];
double tmpVec2[MAX_GRAY];
imCalcGrayHistogram(src, histo, NON_CUMULATIVE); // gray histogram computed
double invHistSum = 1.0 / vecSum(histo, MAX_GRAY); // inverse of the sum
for (i = 0; i < MAX_GRAY; ++i)
p[i] = histo[i] * invHistSum; // equivalent to dividing by the sum, but faster!
m_f[0] = 0.0;
for (i = 1; i < MAX_GRAY; ++i) // m_f = cumsum(g .* p).';
m_f[i] = i * p[i] + m_f[i - 1];
memcpy(m_b, m_f, VEC_DBL_SZ); // m_b = m_f(end) - m_f;
for (i = 0; i < MAX_GRAY; ++i)
m_b[i] = m_f[MAX_GRAY - 1] - m_b[i];
/****************** END OF BINAR_ASHLEY PORTION, START OF ENTROPY_BRINK********************************/
for (i = 0; i < MAX_GRAY; ++i) // tmp0 = m_f_rep ./ g_rep;
{
for (j = 0; j < MAX_GRAY; ++j)
{
tmp0[i][j] = m_f[j] / i;
if ((m_f[j] == 0) || (i == 0))
{
tmp1[i][j] = 0.0; // replace inf or NaN values with 0
tmp3[i][j] = 0.0;
}
else
{
tmp1[i][j] = log(tmp0[i][j]);
tmp3[i][j] = log(1.0 / tmp0[i][j]);;
}
tmp4[i][j] = p[i] * (m_f[j] * tmp1[i][j] + i * tmp3[i][j]);
}
}
diagCumSum(tmpVec1, tmp4); // tmpVec is now the diagonal of the cumulative sum of tmp4
// same operation but for background moment, NOTE: tmp1 through tmp4 get overwritten
for (i = 0; i < MAX_GRAY; ++i)
{
for (j = 0; j < MAX_GRAY; ++j)
{
tmp0[i][j] = m_b[j] / i; // tmpb0 = m_b_rep ./ g_rep;
if ((m_b[j] == 0) || (i == 0))
{
tmp1[i][j] = 0.0; // replace inf or NaN values with 0
tmp3[i][j] = 0.0;
}
else
{
tmp1[i][j] = log(tmp0[i][j]);
tmp3[i][j] = log(1.0 / tmp0[i][j]);;
}
tmp4[i][j] = p[i] * (m_b[j] * tmp1[i][j] + i * tmp3[i][j]);
}
}
sumMinusDiagCumSum(tmpVec2, tmp4); // sum columns, subtract diagonal of cumsum of tmp4
for (i = 0; i < MAX_GRAY; ++i)
tmpVec1[i] += tmpVec2[i];
Topt = calcTopt(m_f, m_b, tmpVec1); // DO I NEED TO ADD ONE?
imProcessThreshold(src, dest, Topt, true);
imProcessBitwiseNot(dest, dest); // HACK ALERT: HAVE TO FLIP BITS
return Topt;
}