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f9.cpp
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f9.cpp
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/*
Copyright 2011 Julien Cayzac. All rights reserved.
Redistribution and use in source and binary forms, with or without
modification, are permitted provided that the following conditions are met:
1. Redistributions of source code must retain the above copyright notice,
this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright
notice, this list of conditions and the following disclaimer in the
documentation and/or other materials provided with the distribution.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS "AS IS" AND ANY EXPRESS
OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN
NO EVENT SHALL THE COPYRIGHT HOLDERS OR CONTRIBUTORS BE LIABLE FOR ANY
DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
(INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
(INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
The views and conclusions contained in the software and documentation are
those of the authors and should not be interpreted as representing official
policies, either expressed or implied, of the copyright holders.
*/
#define BUILDING_F9
#include "f9.h"
class F9::Impl {
private:
std::vector<F9_CORNER> ret_corners;
std::vector<F9_CORNER> nonmax;
std::vector<int> scores;
std::vector<int> row_start;
static inline void makeOffsets(int pixel[], int stride) {
pixel[ 0] = 0 + stride * 3;
pixel[ 1] = 1 + stride * 3;
pixel[ 2] = 2 + stride * 2;
pixel[ 3] = 3 + stride * 1;
pixel[ 4] = 3 + stride * 0;
pixel[ 5] = 3 + stride * -1;
pixel[ 6] = 2 + stride * -2;
pixel[ 7] = 1 + stride * -3;
pixel[ 8] = 0 + stride * -3;
pixel[ 9] = -1 + stride * -3;
pixel[10] = -2 + stride * -2;
pixel[11] = -3 + stride * -1;
pixel[12] = -3 + stride * 0;
pixel[13] = -3 + stride * 1;
pixel[14] = -2 + stride * 2;
pixel[15] = -1 + stride * 3;
}
Impl(const Impl&);
Impl& operator=(const Impl&);
public:
Impl() { }
const std::vector<F9_CORNER>& detectCorners(
const unsigned char* image_data,
int width,
int height,
int bytes_per_row,
unsigned char threshold,
bool suppress_non_max
) {
detectAllCorners(image_data, width, height, bytes_per_row, threshold);
if(!suppress_non_max)
return ret_corners;
cornersScores(image_data, bytes_per_row, threshold);
nonMaxSuppression();
return nonmax;
}
void nonMaxSuppression() {
nonmax.clear();
if(ret_corners.empty())
return;
// Find where each row begins
// (the corners are output in raster scan order). A beginning of -1 signifies
// that there are no corners on that row.
int last_row = ret_corners.back().y;
row_start.resize(last_row + 1);
for(int i(0); i < last_row + 1; ++i)
row_start[i] = -1;
int prev_row = -1;
for(int i(0); i < (int) ret_corners.size(); ++i)
if(ret_corners[i].y != prev_row) {
row_start[ret_corners[i].y] = i;
prev_row = ret_corners[i].y;
}
// Point above points (roughly) to the pixel above the one of interest,
// if there is a feature there.
int point_above(0), point_below(0);
for(int i(0); i < (int) ret_corners.size(); i++) {
int score = scores[i];
const F9_CORNER& pos = ret_corners[i];
// Check left
if(i > 0)
if(ret_corners[i - 1].x == pos.x - 1 && ret_corners[i - 1].y == pos.y && (scores[i - 1] >= score))
continue;
// Check right
if(i + 1 < (int) ret_corners.size())
if(ret_corners[i + 1].x == pos.x + 1 && ret_corners[i + 1].y == pos.y && (scores[i + 1] >= score))
continue;
/*Check above (if there is a valid row above)*/
if(pos.y != 0 && row_start[pos.y - 1] != -1) {
/*Make sure that current point_above is one
row above.*/
if(ret_corners[point_above].y < pos.y - 1)
point_above = row_start[pos.y - 1];
/*Make point_above point to the first of the pixels above the current point,
if it exists.*/
for(; ret_corners[point_above].y < pos.y && ret_corners[point_above].x < pos.x - 1; point_above++)
{}
bool cont(false);
for(int j(point_above); ret_corners[j].y < pos.y && ret_corners[j].x <= pos.x + 1 && !cont; j++) {
int x = ret_corners[j].x;
cont = (x == pos.x - 1 || x == pos.x || x == pos.x + 1) && (scores[j] >= score);
}
if(cont) continue;
}
/*Check below (if there is anything below)*/
if(pos.y != last_row && row_start[pos.y + 1] != -1 && point_below < (int) ret_corners.size()) { /*Nothing below*/
if(ret_corners[point_below].y < pos.y + 1)
point_below = row_start[pos.y + 1];
/* Make point below point to one of the pixels belowthe current point, if it
exists.*/
for(; point_below < (int) ret_corners.size() && ret_corners[point_below].y == pos.y + 1 && ret_corners[point_below].x < pos.x - 1; point_below++)
{}
bool cont(false);
for(int j(point_below); j < (int) ret_corners.size() && ret_corners[j].y == pos.y + 1 && ret_corners[j].x <= pos.x + 1 && !cont; j++) {
int x = ret_corners[j].x;
cont = (x == pos.x - 1 || x == pos.x || x == pos.x + 1) && (scores[j] >= score);
}
if(cont) continue;
}
nonmax.push_back(ret_corners[i]);
}
}
int cornerScore(const unsigned char* p, const int pixel[], unsigned char bstart) {
unsigned char bmin(bstart);
unsigned char bmax(255);
unsigned char b(((int)bmax + (int)bmin) >> 1);
// Compute the score using binary search
for(;;) {
const unsigned char cb((*p > 255 - b) ? 255 : *p + b);
const unsigned char c_b((*p < b) ? 0 : *p - b);
if(p[pixel[0]] > cb)
if(p[pixel[1]] > cb)
if(p[pixel[2]] > cb)
if(p[pixel[3]] > cb)
if(p[pixel[4]] > cb)
if(p[pixel[5]] > cb)
if(p[pixel[6]] > cb)
if(p[pixel[7]] > cb)
if(p[pixel[8]] > cb)
goto is_a_corner;
else if(p[pixel[15]] > cb)
goto is_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[7]] < c_b)
if(p[pixel[14]] > cb)
if(p[pixel[15]] > cb)
goto is_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[14]] < c_b)
if(p[pixel[8]] < c_b)
if(p[pixel[9]] < c_b)
if(p[pixel[10]] < c_b)
if(p[pixel[11]] < c_b)
if(p[pixel[12]] < c_b)
if(p[pixel[13]] < c_b)
if(p[pixel[15]] < c_b)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[14]] > cb)
if(p[pixel[15]] > cb)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[6]] < c_b)
if(p[pixel[15]] > cb)
if(p[pixel[13]] > cb)
if(p[pixel[14]] > cb)
goto is_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[13]] < c_b)
if(p[pixel[7]] < c_b)
if(p[pixel[8]] < c_b)
if(p[pixel[9]] < c_b)
if(p[pixel[10]] < c_b)
if(p[pixel[11]] < c_b)
if(p[pixel[12]] < c_b)
if(p[pixel[14]] < c_b)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[7]] < c_b)
if(p[pixel[8]] < c_b)
if(p[pixel[9]] < c_b)
if(p[pixel[10]] < c_b)
if(p[pixel[11]] < c_b)
if(p[pixel[12]] < c_b)
if(p[pixel[13]] < c_b)
if(p[pixel[14]] < c_b)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[13]] > cb)
if(p[pixel[14]] > cb)
if(p[pixel[15]] > cb)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[13]] < c_b)
if(p[pixel[7]] < c_b)
if(p[pixel[8]] < c_b)
if(p[pixel[9]] < c_b)
if(p[pixel[10]] < c_b)
if(p[pixel[11]] < c_b)
if(p[pixel[12]] < c_b)
if(p[pixel[14]] < c_b)
if(p[pixel[15]] < c_b)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[5]] < c_b)
if(p[pixel[14]] > cb)
if(p[pixel[12]] > cb)
if(p[pixel[13]] > cb)
if(p[pixel[15]] > cb)
goto is_a_corner;
else if(p[pixel[6]] > cb)
if(p[pixel[7]] > cb)
if(p[pixel[8]] > cb)
if(p[pixel[9]] > cb)
if(p[pixel[10]] > cb)
if(p[pixel[11]] > cb)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[12]] < c_b)
if(p[pixel[6]] < c_b)
if(p[pixel[7]] < c_b)
if(p[pixel[8]] < c_b)
if(p[pixel[9]] < c_b)
if(p[pixel[10]] < c_b)
if(p[pixel[11]] < c_b)
if(p[pixel[13]] < c_b)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[14]] < c_b)
if(p[pixel[7]] < c_b)
if(p[pixel[8]] < c_b)
if(p[pixel[9]] < c_b)
if(p[pixel[10]] < c_b)
if(p[pixel[11]] < c_b)
if(p[pixel[12]] < c_b)
if(p[pixel[13]] < c_b)
if(p[pixel[6]] < c_b)
goto is_a_corner;
else if(p[pixel[15]] < c_b)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[6]] < c_b)
if(p[pixel[7]] < c_b)
if(p[pixel[8]] < c_b)
if(p[pixel[9]] < c_b)
if(p[pixel[10]] < c_b)
if(p[pixel[11]] < c_b)
if(p[pixel[12]] < c_b)
if(p[pixel[13]] < c_b)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[12]] > cb)
if(p[pixel[13]] > cb)
if(p[pixel[14]] > cb)
if(p[pixel[15]] > cb)
goto is_a_corner;
else if(p[pixel[6]] > cb)
if(p[pixel[7]] > cb)
if(p[pixel[8]] > cb)
if(p[pixel[9]] > cb)
if(p[pixel[10]] > cb)
if(p[pixel[11]] > cb)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[12]] < c_b)
if(p[pixel[7]] < c_b)
if(p[pixel[8]] < c_b)
if(p[pixel[9]] < c_b)
if(p[pixel[10]] < c_b)
if(p[pixel[11]] < c_b)
if(p[pixel[13]] < c_b)
if(p[pixel[14]] < c_b)
if(p[pixel[6]] < c_b)
goto is_a_corner;
else if(p[pixel[15]] < c_b)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[4]] < c_b)
if(p[pixel[13]] > cb)
if(p[pixel[11]] > cb)
if(p[pixel[12]] > cb)
if(p[pixel[14]] > cb)
if(p[pixel[15]] > cb)
goto is_a_corner;
else if(p[pixel[6]] > cb)
if(p[pixel[7]] > cb)
if(p[pixel[8]] > cb)
if(p[pixel[9]] > cb)
if(p[pixel[10]] > cb)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[5]] > cb)
if(p[pixel[6]] > cb)
if(p[pixel[7]] > cb)
if(p[pixel[8]] > cb)
if(p[pixel[9]] > cb)
if(p[pixel[10]] > cb)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[11]] < c_b)
if(p[pixel[5]] < c_b)
if(p[pixel[6]] < c_b)
if(p[pixel[7]] < c_b)
if(p[pixel[8]] < c_b)
if(p[pixel[9]] < c_b)
if(p[pixel[10]] < c_b)
if(p[pixel[12]] < c_b)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[13]] < c_b)
if(p[pixel[7]] < c_b)
if(p[pixel[8]] < c_b)
if(p[pixel[9]] < c_b)
if(p[pixel[10]] < c_b)
if(p[pixel[11]] < c_b)
if(p[pixel[12]] < c_b)
if(p[pixel[6]] < c_b)
if(p[pixel[5]] < c_b)
goto is_a_corner;
else if(p[pixel[14]] < c_b)
goto is_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[14]] < c_b)
if(p[pixel[15]] < c_b)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[5]] < c_b)
if(p[pixel[6]] < c_b)
if(p[pixel[7]] < c_b)
if(p[pixel[8]] < c_b)
if(p[pixel[9]] < c_b)
if(p[pixel[10]] < c_b)
if(p[pixel[11]] < c_b)
if(p[pixel[12]] < c_b)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[11]] > cb)
if(p[pixel[12]] > cb)
if(p[pixel[13]] > cb)
if(p[pixel[14]] > cb)
if(p[pixel[15]] > cb)
goto is_a_corner;
else if(p[pixel[6]] > cb)
if(p[pixel[7]] > cb)
if(p[pixel[8]] > cb)
if(p[pixel[9]] > cb)
if(p[pixel[10]] > cb)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[5]] > cb)
if(p[pixel[6]] > cb)
if(p[pixel[7]] > cb)
if(p[pixel[8]] > cb)
if(p[pixel[9]] > cb)
if(p[pixel[10]] > cb)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[11]] < c_b)
if(p[pixel[7]] < c_b)
if(p[pixel[8]] < c_b)
if(p[pixel[9]] < c_b)
if(p[pixel[10]] < c_b)
if(p[pixel[12]] < c_b)
if(p[pixel[13]] < c_b)
if(p[pixel[6]] < c_b)
if(p[pixel[5]] < c_b)
goto is_a_corner;
else if(p[pixel[14]] < c_b)
goto is_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[14]] < c_b)
if(p[pixel[15]] < c_b)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[3]] < c_b)
if(p[pixel[10]] > cb)
if(p[pixel[11]] > cb)
if(p[pixel[12]] > cb)
if(p[pixel[13]] > cb)
if(p[pixel[14]] > cb)
if(p[pixel[15]] > cb)
goto is_a_corner;
else if(p[pixel[6]] > cb)
if(p[pixel[7]] > cb)
if(p[pixel[8]] > cb)
if(p[pixel[9]] > cb)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[5]] > cb)
if(p[pixel[6]] > cb)
if(p[pixel[7]] > cb)
if(p[pixel[8]] > cb)
if(p[pixel[9]] > cb)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[4]] > cb)
if(p[pixel[5]] > cb)
if(p[pixel[6]] > cb)
if(p[pixel[7]] > cb)
if(p[pixel[8]] > cb)
if(p[pixel[9]] > cb)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[10]] < c_b)
if(p[pixel[7]] < c_b)
if(p[pixel[8]] < c_b)
if(p[pixel[9]] < c_b)
if(p[pixel[11]] < c_b)
if(p[pixel[6]] < c_b)
if(p[pixel[5]] < c_b)
if(p[pixel[4]] < c_b)
goto is_a_corner;
else if(p[pixel[12]] < c_b)
if(p[pixel[13]] < c_b)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[12]] < c_b)
if(p[pixel[13]] < c_b)
if(p[pixel[14]] < c_b)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[12]] < c_b)
if(p[pixel[13]] < c_b)
if(p[pixel[14]] < c_b)
if(p[pixel[15]] < c_b)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[10]] > cb)
if(p[pixel[11]] > cb)
if(p[pixel[12]] > cb)
if(p[pixel[13]] > cb)
if(p[pixel[14]] > cb)
if(p[pixel[15]] > cb)
goto is_a_corner;
else if(p[pixel[6]] > cb)
if(p[pixel[7]] > cb)
if(p[pixel[8]] > cb)
if(p[pixel[9]] > cb)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[5]] > cb)
if(p[pixel[6]] > cb)
if(p[pixel[7]] > cb)
if(p[pixel[8]] > cb)
if(p[pixel[9]] > cb)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[4]] > cb)
if(p[pixel[5]] > cb)
if(p[pixel[6]] > cb)
if(p[pixel[7]] > cb)
if(p[pixel[8]] > cb)
if(p[pixel[9]] > cb)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[10]] < c_b)
if(p[pixel[7]] < c_b)
if(p[pixel[8]] < c_b)
if(p[pixel[9]] < c_b)
if(p[pixel[11]] < c_b)
if(p[pixel[12]] < c_b)
if(p[pixel[6]] < c_b)
if(p[pixel[5]] < c_b)
if(p[pixel[4]] < c_b)
goto is_a_corner;
else if(p[pixel[13]] < c_b)
goto is_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[13]] < c_b)
if(p[pixel[14]] < c_b)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[13]] < c_b)
if(p[pixel[14]] < c_b)
if(p[pixel[15]] < c_b)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[2]] < c_b)
if(p[pixel[9]] > cb)
if(p[pixel[10]] > cb)
if(p[pixel[11]] > cb)
if(p[pixel[12]] > cb)
if(p[pixel[13]] > cb)
if(p[pixel[14]] > cb)
if(p[pixel[15]] > cb)
goto is_a_corner;
else if(p[pixel[6]] > cb)
if(p[pixel[7]] > cb)
if(p[pixel[8]] > cb)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[5]] > cb)
if(p[pixel[6]] > cb)
if(p[pixel[7]] > cb)
if(p[pixel[8]] > cb)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[4]] > cb)
if(p[pixel[5]] > cb)
if(p[pixel[6]] > cb)
if(p[pixel[7]] > cb)
if(p[pixel[8]] > cb)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[3]] > cb)
if(p[pixel[4]] > cb)
if(p[pixel[5]] > cb)
if(p[pixel[6]] > cb)
if(p[pixel[7]] > cb)
if(p[pixel[8]] > cb)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[9]] < c_b)
if(p[pixel[7]] < c_b)
if(p[pixel[8]] < c_b)
if(p[pixel[10]] < c_b)
if(p[pixel[6]] < c_b)
if(p[pixel[5]] < c_b)
if(p[pixel[4]] < c_b)
if(p[pixel[3]] < c_b)
goto is_a_corner;
else if(p[pixel[11]] < c_b)
if(p[pixel[12]] < c_b)
goto is_a_corner;
else
goto is_not_a_corner;
else
goto is_not_a_corner;
else if(p[pixel[11]] < c_b)
if(p[pixel[12]] < c_b)
if(p[pixel[13]] < c_b)
goto is_a_corner;
else
goto is_not_a_corner;
else