java中彩色图像到灰度图像（512级灰度）的转换

Question

I am trying to convert a colored image to grayscale. The result should be 512 shades of grey.

How can I convert the pixel value to 9 bit so that I get 512 shades?

Answer 1

I dont know how to do it in 9 bits but if you want value of your image in range of 0 to 511, this can be done in following manner.

im = imread('lena.png'); 
im = double(im);
gray = 0.2989*im(:,:,1)+0.5870*im(:,:,2)+0.1140*im(:,:,3);
gray  = 511*mat2gray(gray); % scale image b/w 0 and 1;

This is my thought, please give us some more explanation with your code, so that anyone here can suggest solution of your problem.

Thank You