public unsafe TImage GaussPyramidDown()
{
int width = Width;
int height = Height;
int ww = width * 2;
int hh = height * 2;
TImage imgDown = new TImage(ww, hh);
TPixel* imgStart = this.Start;
TPixel* imgPyDownStart = imgDown.Start;
int hSrc, wSrc;
TPixel* lineSrc;
TPixel* lineDst;
TPixel p0, p1, p2, p3;
// 分四种情况进行处理：
// (1) h,w 都是偶数；
// (2) h 是偶数， w 是奇数
// (3) h 是奇数， w 是偶数
// (4) h 是奇数， w 是奇数
// h 是偶数
for (int h = 0; h < hh; h += 2)
{
hSrc = h / 2;
lineDst = imgPyDownStart + h * ww;
lineSrc = imgStart + hSrc * width;
// w 是偶数
for (int w = 0; w < ww; w += 2)
{
wSrc = w / 2;
lineDst[w] = lineSrc[wSrc];
}
// w 是奇数
for (int w = 1; w < ww; w += 2)
{
// 防止取到最后一列
wSrc = Math.Min(w / 2,width-2);
p0 = lineSrc[wSrc];
p1 = lineSrc[wSrc + 1];
lineDst[w] = new TPixel((TChannel)((p0.Red + p1.Red) >> 1),
(TChannel)((p0.Green + p1.Green) >> 1),
(TChannel)((p0.Blue + p1.Blue) >> 1),
(TChannel)((p0.Alpha + p1.Alpha) >> 1));
}
}
// h 是奇数
for (int h = 1; h < hh; h += 2)
{
// 防止取到最后一行
hSrc = Math.Min(h / 2, height - 2);
lineDst = imgPyDownStart + h * ww;
lineSrc = imgStart + hSrc * width;
// w 是偶数
for (int w = 0; w < ww; w += 2)
{
wSrc = w / 2;
p0 = lineSrc[wSrc];
p1 = lineSrc[wSrc + width];
lineDst[w] = new TPixel((TChannel)((p0.Red + p1.Red) >> 1),
(TChannel)((p0.Green + p1.Green) >> 1),
(TChannel)((p0.Blue + p1.Blue) >> 1),
(TChannel)((p0.Alpha + p1.Alpha) >> 1));
}
// w 是奇数
for (int w = 1; w < ww; w += 2)
{
// 防止取到最后一列
wSrc = Math.Min(w / 2, width - 2);
p0 = lineSrc[wSrc];
p1 = lineSrc[wSrc + 1];
p2 = lineSrc[wSrc + width];
p3 = lineSrc[wSrc + width + 1];
lineDst[w] = new TPixel((TChannel)((p0.Red + p1.Red + p2.Red + p3.Red) >> 2),
(TChannel)((p0.Green + p1.Green + p2.Green + p3.Green) >> 2),
(TChannel)((p0.Blue + p1.Blue + p2.Blue + p3.Blue) >> 2),
(TChannel)((p0.Alpha + p1.Alpha + p2.Alpha + p3.Alpha) >> 2));
}
}
return imgDown;
}
public unsafe TImage GaussPyramidUp()
{
int width = this.Width;
int height = this.Height;
int ww = width / 2;
int hh = height / 2;
TImage imgUp = new TImage(ww, hh);
TPixel* imgStart = Start;
TPixel* imgPyUpStart = imgUp.Start;
int hSrc, wSrc;
TPixel* lineSrc;
TPixel* lineDst;
for (int h = 0; h < hh; h++)
{
hSrc = 2 * h;
lineSrc = imgStart + hSrc * width;
lineDst = imgPyUpStart + h * ww;
for (int w = 0; w < ww; w++)
{
wSrc = 2 * w;
// 对于四边不够一个高斯核半径的地方，直接赋值
if (hSrc < 2 || hSrc > height - 3 || wSrc < 2 || wSrc > width - 3)
{
lineDst[w] = lineSrc[wSrc];
}
else
{
// 计算高斯
TPixel* p = lineSrc + wSrc - 2 * width;
TPixel p00 = p[-2];
TPixel p01 = p[-1];
TPixel p02 = p[0];
TPixel p03 = p[1];
TPixel p04 = p[2];
p += width;
TPixel p10 = p[-2];
TPixel p11 = p[-1];
TPixel p12 = p[0];
TPixel p13 = p[1];
TPixel p14 = p[2];
p += width;
TPixel p20 = p[-2];
TPixel p21 = p[-1];
TPixel p22 = p[0];
TPixel p23 = p[1];
TPixel p24 = p[2];
p += width;
TPixel p30 = p[-2];
TPixel p31 = p[-1];
TPixel p32 = p[0];
TPixel p33 = p[1];
TPixel p34 = p[2];
p += width;
TPixel p40 = p[-2];
TPixel p41 = p[-1];
TPixel p42 = p[0];
TPixel p43 = p[1];
TPixel p44 = p[2];
//int alpha =
// 1 * p00.Alpha + 04 * p01.Alpha + 06 * p02.Alpha + 04 * p03.Alpha + 1 * p04.Alpha
// + 4 * p10.Alpha + 16 * p11.Alpha + 24 * p12.Alpha + 16 * p13.Alpha + 4 * p14.Alpha
// + 6 * p20.Alpha + 24 * p21.Alpha + 36 * p22.Alpha + 24 * p23.Alpha + 6 * p24.Alpha
// + 4 * p30.Alpha + 16 * p31.Alpha + 24 * p32.Alpha + 16 * p33.Alpha + 4 * p34.Alpha
// + 1 * p40.Alpha + 04 * p41.Alpha + 06 * p42.Alpha + 04 * p43.Alpha + 1 * p44.Alpha;
int red =
1 * p00.Red + 04 * p01.Red + 06 * p02.Red + 04 * p03.Red + 1 * p04.Red
+ 4 * p10.Red + 16 * p11.Red + 24 * p12.Red + 16 * p13.Red + 4 * p14.Red
+ 6 * p20.Red + 24 * p21.Red + 36 * p22.Red + 24 * p23.Red + 6 * p24.Red
+ 4 * p30.Red + 16 * p31.Red + 24 * p32.Red + 16 * p33.Red + 4 * p34.Red
+ 1 * p40.Red + 04 * p41.Red + 06 * p42.Red + 04 * p43.Red + 1 * p44.Red;
int green =
1 * p00.Green + 04 * p01.Green + 06 * p02.Green + 04 * p03.Green + 1 * p04.Green
+ 4 * p10.Green + 16 * p11.Green + 24 * p12.Green + 16 * p13.Green + 4 * p14.Green
+ 6 * p20.Green + 24 * p21.Green + 36 * p22.Green + 24 * p23.Green + 6 * p24.Green
+ 4 * p30.Green + 16 * p31.Green + 24 * p32.Green + 16 * p33.Green + 4 * p34.Green
+ 1 * p40.Green + 04 * p41.Green + 06 * p42.Green + 04 * p43.Green + 1 * p44.Green;
int blue =
1 * p00.Blue + 04 * p01.Blue + 06 * p02.Blue + 04 * p03.Blue + 1 * p04.Blue
+ 4 * p10.Blue + 16 * p11.Blue + 24 * p12.Blue + 16 * p13.Blue + 4 * p14.Blue
+ 6 * p20.Blue + 24 * p21.Blue + 36 * p22.Blue + 24 * p23.Blue + 6 * p24.Blue
+ 4 * p30.Blue + 16 * p31.Blue + 24 * p32.Blue + 16 * p33.Blue + 4 * p34.Blue
+ 1 * p40.Blue + 04 * p41.Blue + 06 * p42.Blue + 04 * p43.Blue + 1 * p44.Blue;
lineDst[w] = new TPixel(red >> 8, green >> 8, blue >> 8, 255);
}
}
}
return imgUp;
}
public unsafe TImage FastPyramidUp4X()
{
int width = this.Width;
int height = this.Height;
int ww = width / 4;
int hh = height / 4;
TImage imgUp = new TImage(ww, hh);
TPixel* imgStart = Start;
TPixel* imgPyUpStart = imgUp.Start;
TPixel* lineSrc;
TPixel* lineDst;
for (int h = 0; h < hh; h++)
{
lineSrc = imgStart + 4 * h * width;
lineDst = imgPyUpStart + h * ww;
for (int w = 0; w < ww; w++)
{
lineDst[w] = lineSrc[4 * w];
}
}
return imgUp;
}
