我正在尝试在我的项目中实现积分图像概念（基于此解释https://computersciencesource.wordpress.com/2010/09/03/computer-vision-the-integral-image/），但我遇到了一些问题。
我有方形（N * N）矩阵，其中有双值，我计算相应的SAT表。在下一步，我想知道值的总和 在方形块（L * L）中从主对角线上的R索引开始。我不知道我是否能够很好地解释它，但我希望我的代码能够比我更好地与你交谈;）
public class Testing {
public Testing() {
double[][] values = {
{0.00,0.00,0.00,0.00,0.00,0.00,3.95,4.35,1.92,12.07,14.16,134.88},
{0.00,0.00,0.00,0.00,0.00,0.00,0.00,4.74,1.13,12.23,5.70,89.01},
{0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,2.10,13.72,1.49,71.94},
{0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,7.58,7.79,55.21},
{0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,7.79,33.01},
{0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,3.92},
{5.39,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,22.09},
{9.34,0.39,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,37.28},
{5.79,4.35,3.23,0.00,0.00,0.00,0.00,0.00,0.00,0.00,0.00,47.29},
{5.67,3.82,0.97,6.30,0.00,0.00,0.00,0.00,0.00,0.00,0.00,47.29},
{24.11,6.31,6.45,13.88,0.00,0.00,0.00,0.00,0.00,0.00,0.00,47.29},
{46.09,69.39,55.13,46.03,41.76,7.00,31.91,43.70,58.39,98.75,132.71,0.00}
};
double[][] sat = calculateSAT(values);
int size = sat.length;
for (int r = 0; r < size; r++) {
System.out.println("R: " + r);
for (int l = 2; l <= size - r; l++) {
int blockSize = l - 1;
double s_A, s_B, s_C, s_D = sat[r + blockSize][r + blockSize];
if (r == 0) {
s_A = 0;
s_B = 0;
s_C = 0;
}
else {
s_A = sat[r - 1][r - 1];
s_B = sat[r + blockSize][r - 1];
s_C = sat[r - 1][r + blockSize];
}
System.out.println("L: " + l);
System.out.println("Sum: " + (s_A + s_D - s_B - s_C));
}
System.out.println("-------------");
}
}
public double[][] calculateSAT(double[][] matrix) {
int size = matrix.length;
double[][] sat = new double[size][size];
for (int x = 0; x < size; x++) {
for (int y = 0; y < size; y++) {
double ixy = matrix[x][y], sat_left = 0.0, sat_top = 0.0, sat_lefttop = 0.0;
if (x == 0) {
sat_left = 0;
sat_lefttop = 0;
}
else {
sat_left = sat[x-1][y];
}
if (y == 0) {
sat_top = 0;
sat_lefttop = 0;
}
else {
sat_top = sat[x][y-1];
}
if (x != 0 && y != 0) {
sat_lefttop = sat[x-1][y-1];
}
sat[x][y] = ixy + sat_left + sat_top - sat_lefttop;
}
}
printSAT(sat);
return sat;
}
public void printSAT(double[][] sat) {
for (int x = 0; x < sat.length; x++) {
for (int y = 0; y < sat.length; y++) {
System.out.print(sat[x][y] + "\t");
}
System.out.println();
}
System.out.println("-------------");
}
public static void main(String[] args) {
new Testing();
System.out.println("All done! :D");
}
}
输出是这样的：
0.0 0.0 0.0 0.0 0.0 0.0 3.95 8.3 10.22 22.29 36.45 171.32999999999998
0.0 0.0 0.0 0.0 0.0 0.0 3.95 13.040000000000003 16.090000000000003 40.39 60.25000000000001 284.14
0.0 0.0 0.0 0.0 0.0 0.0 3.95 13.040000000000003 18.190000000000005 56.21000000000001 77.56000000000002 373.39
0.0 0.0 0.0 0.0 0.0 0.0 3.95 13.040000000000003 18.190000000000005 63.79000000000001 92.93000000000004 443.96999999999997
0.0 0.0 0.0 0.0 0.0 0.0 3.95 13.040000000000003 18.190000000000005 63.79000000000001 100.72000000000003 484.77
0.0 0.0 0.0 0.0 0.0 0.0 3.95 13.040000000000003 18.190000000000005 63.79000000000001 100.72000000000003 488.69000000000005
5.39 5.39 5.39 5.39 5.39 5.39 9.34 18.430000000000003 23.580000000000002 69.18 106.11000000000001 516.1700000000001
14.73 15.119999999999997 15.119999999999997 15.119999999999997 15.119999999999997 15.119999999999997 19.069999999999997 28.16 33.31 78.91000000000001 115.84000000000003 563.1800000000001
20.52 25.259999999999994 28.489999999999995 28.489999999999995 28.489999999999995 28.489999999999995 32.43999999999999 41.53 46.68000000000001 92.28000000000002 129.21000000000004 623.84
26.189999999999998 34.75 38.95 45.25 45.25 45.25 49.2 58.29000000000001 63.440000000000026 109.04000000000002 145.97000000000003 687.89
50.3 65.17 75.82000000000001 96.00000000000001 96.0 96.0 99.94999999999999 109.04 114.19 159.79 196.71999999999997 785.9299999999998
96.39 180.64999999999998 246.43 312.64000000000004 354.40000000000003 361.40000000000003 397.26 450.05 513.59 657.94 827.58 1416.7899999999997
-------------
R: 0
L: 2
Sum: 0.0
L: 3
Sum: 0.0
L: 4
Sum: 0.0
L: 5
Sum: 0.0
L: 6
Sum: 0.0
L: 7
Sum: 9.34
L: 8
Sum: 28.16
L: 9
Sum: 46.68000000000001
L: 10
Sum: 109.04000000000002
L: 11
Sum: 196.71999999999997
L: 12
Sum: 1416.7899999999997
-------------
R: 1
L: 2
Sum: 0.0
L: 3
Sum: 0.0
L: 4
Sum: 0.0
L: 5
Sum: 0.0
L: 6
Sum: 0.0
L: 7
Sum: 5.129999999999999
L: 8
Sum: 15.940000000000007
L: 9
Sum: 60.560000000000024
L: 10
Sum: 109.96999999999996
L: 11
Sum: 1149.0699999999997
-------------
R: 2
L: 2
Sum: 0.0
L: 3
Sum: 0.0
L: 4
Sum: 0.0
L: 5
Sum: 0.0
L: 6
Sum: 0.0
L: 7
Sum: 5.330000000000009
L: 8
Sum: 33.90000000000002
L: 9
Sum: 71.29999999999995
L: 10
Sum: 951.9999999999999
-------------
R: 3
L: 2
Sum: 0.0
L: 3
Sum: 0.0
L: 4
Sum: 0.0
L: 5
Sum: 0.0
L: 6
Sum: 7.105427357601002E-15
L: 7
Sum: 13.88000000000001
L: 8
Sum: 43.33999999999995
L: 9
Sum: 796.9699999999997
-------------
R: 4
L: 2
Sum: 0.0
L: 3
Sum: 0.0
L: 4
Sum: 0.0
L: 5
Sum: 7.105427357601002E-15
L: 6
Sum: 7.105427357601002E-15
L: 7
Sum: 7.789999999999921
L: 8
Sum: 660.1799999999996
-------------
R: 5
L: 2
Sum: 0.0
L: 3
Sum: 0.0
L: 4
Sum: 7.105427357601002E-15
L: 5
Sum: 7.105427357601002E-15
L: 6
Sum: -5.6843418860808015E-14
L: 7
Sum: 577.6199999999997
-------------
R: 6
L: 2
Sum: 0.0
L: 3
Sum: 7.105427357601002E-15
L: 4
Sum: 7.105427357601002E-15
L: 5
Sum: -5.6843418860808015E-14
L: 6
Sum: 566.6999999999996
-------------
R: 7
L: 2
Sum: 1.7763568394002505E-14
L: 3
Sum: 1.4210854715202004E-14
L: 4
Sum: -2.8421709430404007E-14
L: 5
Sum: 512.6999999999996
-------------
R: 8
L: 2
Sum: -1.4210854715202004E-14
L: 3
Sum: -7.105427357601002E-14
L: 4
Sum: 431.7199999999998
-------------
R: 9
L: 2
Sum: -5.6843418860808015E-14
L: 3
Sum: 326.03999999999974
-------------
R: 10
L: 2
Sum: 179.99999999999966
-------------
R: 11
-------------
All done! :D
我对此代码的问题是其中一些总和为负数。那可能吗？如果我正确理解SAT表，那就不可能。
由于这些值非常小，这是双精度问题吗？
非常感谢你的帮助:)。
PS：对不起，我的英语并不比这更好。答案 0 :(得分：1)
是的，负值是由精度问题引起的。如果数字足够小，则将其视为零。