大家好，我是小曜，我来为大家解答以上问题。idx是什么意思，idx很多人还不知道，现在让我们一起来看看吧！

1、什么叫归一化？怎么联系到HSI格式的？

2、我理解的归一化是将数据变成某种相对值关系（它是一种无量纲处理手段），例如：将0~255这间的数据double化为0~1（相对值）。

3、从RGB到HSI只是对同一图像用不同的方式表示，这样有利于使用不同的方法进行处理。

4、例如：我想将一幅图像的饱和度提高，那么直接用RGB不太容易，于是转化为HSI后，就非常容易了。

5、下面是转换代码RGB和HSI的互换代码。

6、--------------------------------------------------------------------------

7、function hsi=rgb2hsi(rgb)

8、%RGB2HSI Converts an RGB image to HSI

9、% HSI=RGB2HSI(rgb) converts an RGB image to HSI. The input image is

10、% assumed to be of size M-by-N-by-3, where the third dimension accounts

11、% for three image planes:red, green, and blue, in that order. If all RGB

12、% component images are equal, the HSI conversion is undefined. Ths input

13、% image can be of class double (with values in the rang[0,1]), uint8, or

14、% uint16.

15、% The output image, HSI, is of class double, where:

16、% hsi(:,:,1)= hue image normalized values to the range [0,1] by

17、% dividing all angle values by 2*pi.

18、% hsi(:,:,2)=saturation image, in the range [0,1].

19、% hsi(:,:,3)=intensity image, in the range [0,1].

20、%Extract the individual component images.

21、rgb=im2double(rgb);

22、r=rgb(:,:,1);

23、g=rgb(:,:,2);

24、b=rgb(:,:,3);

25、%Implement the conversion equations.

26、num=0.5*((r-g)+(r-b));

27、den=sqrt((r-g).^2+(r-b).*(g-b));

28、theta=acos(num./(den+eps));

29、H=theta;

30、H(b>g)=2*pi-H(b>g);

31、H=H/(2*pi);

32、num=min(min(r,g),b);

33、den=r+g+b;

34、den(den==0)=eps;

35、S=1-3.*num./den;

36、H(S==0)=0;

37、I=(r+g+b)/3;

38、%Combine all three results into an hsi image.

39、hsi=cat(3,H,S,I);

40、function rgb=hsi2rgb(hsi)

41、%HSI2RGB Converts an HSI image to RGB.

42、% HSI2RGB Converts an HSI image to RGB, where HSI is assumed to be of

43、% class double with:

44、% hsi(:,:,1)= hue image normalized values to the range [0,1] by

45、% dividing all angle values by 2*pi.

46、% hsi(:,:,2)=saturation image, in the range [0,1].

47、% hsi(:,:,3)=intensity image, in the range [0,1].

48、% The components of the output image are:

49、% rgb(:,:,1)=red;

50、% rgb(:,:,2)=green.

51、% rgb(:,:,3)=blue.

52、%Extract the individaul HSI component images.

53、H=hsi(:,:,1)*2*pi;

54、S=hsi(:,:,2);

55、I=hsi(:,:,3);

56、%Implement the conversion equations.

57、R=zeros(size(hsi,1),size(hsi,2));

58、G=zeros(size(hsi,1),size(hsi,2));

59、B=zeros(size(hsi,1),size(hsi,2));

60、% RG sector (0<=H<2*pi/3).

61、idx=find((0<=H)&(H<2*pi/3));

62、B(idx)=I(idx).*(1-S(idx));

63、R(idx)=I(idx).*(1+S(idx).*cos(H(idx))./cos(pi/3-H(idx)));

64、G(idx)=3*I(idx)-(R(idx)+B(idx));

65、%BG sector (2*pi/3<=H<4*pi/3).

66、idx=find((2*pi/3<=H)&(H<4*pi/3));

67、R(idx)=I(idx).*(1-S(idx));

68、G(idx)=I(idx).*(1+S(idx).*cos(H(idx)-2*pi/3)./cos(pi-H(idx)));

69、B(idx)=3*I(idx)-(R(idx)+G(idx));

70、%BR sector.

71、idx=find((4*pi/3<=H)&(H<=2*pi));

72、G(idx)=I(idx).*(1-S(idx));

73、B(idx)=I(idx).*(1+S(idx).*cos(H(idx)-4*pi/3)./cos(5*pi/3-H(idx)));

74、R(idx)=3*I(idx)-(G(idx)+B(idx));

75、%Combine all three results into an RGB image. Clip to [0,1] to compensate for floating-point arithmetic rounding effects.

76、rgb=cat(3,R,G,B);

77、rgb=max(min(rgb,1),0);

本文到此讲解完毕了，希望对大家有帮助。