mat2gray函数将一个数据矩阵转化为一个灰度图像 >> i=imread('rice.png');
>> j=filter2(fspecial('sobel'),i); >> k=mat2gray(j); >> imshow(i)
>> figure,imshow(k)
rgb2gary函数将真彩色图像转化为灰度图像 >> [x,map]=imread('rice.png');
>> np=rgb2gray(map);
??? Error using ==> rgb2gray>parse_inputs MAP must be a m x 3 array.
Error in ==> rgb2gray at 35 X = parse_inputs(varargin{:}); ？？？？？？？？？？？？ >> rgb=imread('peppers.png');
>> [X_nodither,map]=rgb2ind(rgb,8,'nodither'); >> [X_dither,map]=rgb2ind(8,'dither'); >> subplot(131),imshow(rgb);
>> subplot(132),imshow(X_nodither,map); %无抖动 >> subplot(133),imshow(X_dither,map) %有抖动
im2bw函数通过设定阈值将真彩、索引和灰度图像转化为二值图像 >> load trees
>> b=im2bw(X,map,.4); >> imshow(X,map) >> figure,imshow(b)
>> rgb=reshape(ones(64,1)*reshape(jet(64),1,192),[64,64,3]);
>> hsv=rgb2hsv(rgb); >> h=hsv(:,:,1); >> s=hsv(:,:,2); >> v=hsv(:,:,3); >> subplot(221)
>> imshow(h),title('色调')
>> subplot(222),imshow(s),title('饱和度') >> subplot(223),imshow(v),title('亮度')
>> subplot(224),imshow(h),title('原真彩色调色板')
>> rgb=imread('peppers.png'); >> yiq=rgb2ntsc(rgb);
>> subplot(121),imshow(rgb),title('原始rgb图像')
>> subplot(122),imshow(yiq(:,:,1)),title('变换后的ntsc图像')
>> rgb=imread('peppers.png'); >> hsv=rgb2hsv(rgb);
>> subplot(121),imshow(rgb),title('原始rgb图像')
>> subplot(122),imshow(hsv),title('变换后的hsv图像')
>> rgb=imread('peppers.png'); >> ycbcr=rgb2ycbcr(rgb);
>> subplot(121),imshow(rgb),title('原始rgb图像')
>> subplot(122),imshow(ycbcr),title('变换后的ycbcr图像')
色彩重排
>> [x,map]=imread('canoe.tif'); >> [y,newmap]=cmpermute(x,map);
>>map
。。。。。。。。 >>newmap
。。。。。。。。
褪色前后
>> [x,map]=imread('canoe.tif'); >> [y,newmap]=imapprox(x,map,20); >> imshow(x,map)
>> figure,imshow(y,newmap)
