获取全暗输出图像

Question

如果我在给矩阵 B 设置大小时删除 uint8，我得到的输出会被红色平面遮盖。我还在imshow(B, [])中添加了[]来解决全暗输出的问题，但它没有帮助。

function myThirdAssignment(I,WindowSize,K0,K1,K2)

%if size(I,3)==1
 

 %[rows, columns, numberOfColorChannels] = size(I);
 
%elseif size(I,3)==3
    
x= im2double(imread(I));
%gray1=rgb2gray(x);
%[r, c, numberOfColorChannels] = size(gray1);
%end


if nargin==1 % If number of arguments of the function are equal to 1 then use 
             % the following default values for K0,K1,K2, & Window size.
    K0= 0.5;
    
    K1= 1;
    
    K2= 0.5;
    
    WindowSize=3;
end

figure(1); imshow(x); title('ORIGINAL IMAGE');
imwrite(x,'OriginalImage.bmp.bmp'); %writing data of original image in to current directory.

% GIVING B THE SAME ROWS AND COLUMS AS THE ORIGINAL IMAGE
[rows, columns, numberOfColorChannels] = size(x);
B = zeros(rows, columns, numberOfColorChannels, 'uint8');


% CALCULATING CEIL & FLOOR VALUES TO MAKE PROGRAM MORE GENERAL
p= ceil((WindowSize / 2)); %3/2= 1.5=2


s= floor((WindowSize / 2)); %3/2=1.5=1



        
        
        
        
           
            B(i,j)= 2*x(i,j);
            
        
        
        else
            B(i,j)= x(i,j);
        end
    
        %--------------------------------------------
        
    end


end

%RGB = cat(3, B, B, B);
figure(2);imshow(B, []); title('IMAGE AFTER LOCAL HISTOGRAM EQUALIZATION');
imwrite(B,'enhancedImage.jpeg.jpeg'); %writing data of enhanced image in to current directory

end

我使用 this image 作为输入。

Answer 1

x是double (im2double)，意思是它的值在0到1之间。

您将其存储在 0-255 的无符号整数上，B。作为无符号整数，它将裁剪所有小数位并舍入到最接近的整数，即 0。因此 B(i,j)= x(i,j) 始终为零。

您的意思可能是 B(i,j)= x(i,j)*255 ?

或者更好的是，始终对双精度数进行运算，然后在保存之前转换 int，如果需要的话。

Answer 2

这里有两个问题：a) 您已经解决的 uint8 问题，它将双精度值转换为 uint8，将所有值四舍五入为 0，导致图像变暗，以及 b) 生成的红色图像是因为您仅在输入图像 x 的红色通道上执行局部直方图均衡，而输出图像中的绿色和蓝色通道为零。

将您的代码更改为：

if avg <= K0*(meanIntensity) && (K1*(stdG) <= std) && (std <= K2*(stdG))
           % only enhance an area of defined window size when its mean/average is 
           % lesser than or equal to the mean of the image by some constant
           % K0 AND its standard deviation is lesser than the value of the
           % standard deviation by a constant K2 and greater than the
           % global standard deviation by a constant K1.
           
            B(i,j,1)= 2*x(i,j,1);
            B(i,j,2)= 2*x(i,j,2);
            B(i,j,3)= 2*x(i,j,3);
        
        
        else
            B(i,j,1)= x(i,j,1);
            B(i,j,2)= x(i,j,2);
            B(i,j,3)= x(i,j,3);
        end

获取全暗输出图像

Getting all dark output image

matlab

local

histogram