Fix : image/conv2 & dsp/conv, p_median3x3_f32 : hardwired network

[ebadi]

dsp/p_conv_f32: Remove an extra element in the result, Fix a problem in involving uninitialize memory addresses in computation.
image/p_conv2d_f32: Returns incorrect values as it doesn't flip the kernel in vertical and horizontal directions, Support for rectangular kernels.
image/p_median3x3.c: For 3x3 median filter, I replaced it with hardwired median search described here: http:users.utcluj.ro/~baruch/resources/Image/xl23_16.pdf
README.md: Typo

Counter example for p_conv_f32

Response from FreeMat:

--> x = [1, 2, 3, 4];
--> h = [5,6,7];
--> r = conv(x, h)
r =
  5 16 34 52 45 28 

Response from pal:
100.000000, 105.000000, 116.000000, 134.000000, 152.000000, 145.000000, 128.000000, 100.000000

   float x[4] = {1,2,3,4};
   float h[3] = {5,6,7} ;
   float r[10] = {100,100,100,100,100,100, 100, 100,100, 100};  
   p_conv_f32( x, h , r ,4 ,3);
   printf ("%f, %f, %f, %f, %f, %f, %f, %f", r[0], r[1], r[2], r[3], r[4], r[5], r[6], r[7]);

Counter example for p_conv2d_f32

Response from FreeMat:

--> A= [17 24 1 8 15; 23 5 7 14 16; 4 6 13 20 22;10 12 19 21 3; 11 18 25 2 9]
--> B=[1 3 1; 0 5 0; 2 1 2]
--> E=[0 0 0; 0 1 0; 0 0 0]
--> C2 = conv2(A,E,'valid')   <-- works correctly since kernel is symmetric   
--> C1 = conv2(A,B,'valid')   <-- Doesn't work correctly

120, 165, 205,
160, 200, 245,
190, 255, 235,

Response from pal:
155.0, 135.0, 200.0,
145.0, 190.0, 230.0,
185.0, 225.0, 270.0,

#define W 5
#define W2 (W-2)
int main(int argc, char *argv[])
{
   int i, j;
   float src[5*5] = {17,24,1,8,15,
                    23,5,7,14,16,
                    4,6,13,20,22,
                    10,12,19,21,3,
                    11,18,25,2,9 };
   float kernel[3*3] = {
          1,3,1,
          0,5,0,
          2,1,2 };
    float dest[3*3];
    p_conv2d_f32(src, kernel, dest, 5, 5, 3);

    for (i = 0; i < W; i++) {
        for (j = 0; j < W; j++) {       
            printf("%.1f, ", src[i*W+j]);
        }
        printf("\n");
    }

    printf("\n");

    for (i = 0; i < W2; i++) {
        for (j = 0; j < W2; j++) {
            printf("%.1f, ", dest[i*W2+j]);
        }
        printf("\n");
    }
}

Old pull request : #100

[mateunho]

For p_median3x3: duplicate of #132

[ebadi]

No it is not duplicate of #132. I mentioned that 9day ago in #100 ; but it is not merged since then; Because of many changes in function signatures I decided to close that pull request and open a new pull request.

[mateunho]

@ebadi sorry, my oversight.