double
Get_Skew::histogram( const Raster &raster, double angle)
{
int i;
double sum;
double mean;
double angle_diff = tan(angle / (180.0 / M_PI));
int diff_y = -static_cast<int>( raster.width() * angle_diff);
int min_y = max( 0, diff_y);
int max_y = min( static_cast<int>( raster.height())
, raster.height() + diff_y);
int num_rows;
Fixed dx;
int dy;
if (raster.height() > m_max_rows) {
delete []m_rows;
m_rows = new unsigned[ raster.height()];
m_max_rows = raster.height();
}
num_rows = (max_y - min_y) / m_sample_skip + 1;
if (angle < 0) {
dy = -1;
} else {
dy = +1;
}
if ((-0.05 < angle) && (angle < 0.05)) {
dx = static_cast<int>( raster.width());
} else {
dx = dy / (tan( angle / (180.0 / M_PI)));
}
for (i = 0; i < num_rows; ++i) {
m_rows[ i] = cast_ray( raster, min_y + i * m_sample_skip, dx, dy);
}
sum = 0.0;
for (i = 0; i < num_rows; ++i) {
sum += m_rows[ i];
}
mean = sum / num_rows;
sum = 0.0;
for (i = 0; i < num_rows; ++i) {
sum += sqr( m_rows[ i] - mean);
}
return sum / num_rows;
}
bool
Invert::do_invert( const Raster &src, Raster &dest)
{
try {
if (&src != &dest) {
dest.redimension( src.width(), src.height(), src.depth(), src.interp());
}
size_t words = src.data_words();
Raster_Word * s = src.raster_word();
Raster_Word * d = src.raster_word();
for (size_t i = 0; i < words; ++i) {
d[ i] = ~s[ i];
}
return true;
}
catch (...) {
return false;
}
}
unsigned
Get_Skew::cast_ray( const Raster &raster, int row, const Fixed &dx, int dy)
{
unsigned bits = 0;
Fixed start = 0;
Fixed end = 0;
Fixed width = static_cast<int>( raster.width());
int r = row;
while (start < width) {
end = start + dx;
if (end > width) {
end = width;
}
bits += bit_count( raster[ r]
, static_cast<int>( start)
, static_cast<int>( end));
start = end;
r += dy;
}
return bits;
}
