Gdip_FilterColor

int Gdip_FilterColor(unsigned char * Bitmap, int w, int h, int Stride, unsigned int Color, unsigned int ReplaceColor, int v)
{
    unsigned int p, A1, R1, G1, B1, A2, R2, G2, B2, tA, tR, tG, tB;

    A1 = (Color & 0xff000000) >> 24;
    R1 = (Color & 0x00ff0000) >> 16;
    G1 = (Color & 0x0000ff00) >> 8;
    B1 = Color & 0x000000ff;

    A2 = (ReplaceColor & 0xff000000) >> 24;
    R2 = (ReplaceColor & 0x00ff0000) >> 16;
    G2 = (ReplaceColor & 0x0000ff00) >> 8;
    B2 = ReplaceColor & 0x000000ff;

    for (int y = 0; y < h; ++y)
    {
        for (int x = 0; x < w; ++x)
        {
            p = (4*x)+(y*Stride);

            tA = Bitmap[3+p];
            tR = Bitmap[2+p];
            tG = Bitmap[1+p];
            tB = Bitmap[p];

            if ((tA <= A1+v && tA >= A1-v) && (tR <= R1+v && tR >= R1-v) && (tG <= G1+v && tG >= G1-v) && (tB <= B1+v && tB >= B1-v))
            {
                Bitmap[3+p] = A2;
                Bitmap[2+p] = R2;
                Bitmap[1+p] = G2;
                Bitmap[p] = B2;
            }

        }
    }
    return 0;
}