Question

我有以下用MATLAB编写的代码，摘自this paper on page 3:

function [ ii_image ] = RGB2IlluminationInvariant( image, alpha )
ii_image = 0.5 + log(image(:,:,2)) - alpha*log(image(:,:,3)) - (1-alpha)*log(image(:,:,1));

此代码应将3通道RGB图像转换为其照度不变。我想知道代码在做什么，以便可以在Java中实现它。

根据我的收集，它正在计算每个红色/绿色/蓝色像素的对数，并将它们彼此相减，但结果不是整数，因此我无法将其应用于Java的{更改RGB值时为{1}}类。如何在Java中模拟此功能？

Answer 1

将函数转换为JAVA并不难。
以下代码示例是一个MATLAB实现，可以直接转换为JAVA。

您应注意输入和输出元素的范围和类型以及内存顺序。

阅读以下代码中的注释：

%function [ ii_image ] = RGB2IlluminationInvariant( image, alpha )

%Initialize input (for executing the example):
image = imread('peppers.png');
image = max(image, 1); %Replace zero values with 1, because log(0) is -Inf
image = double(image)/255; %Convert image to double in range [1/255, 1]. In JAVA, you should use double(pix)/255 if pix is a byte in range [0, 255].
alpha = 0.9;

ii_image = 0.5 + log(image(:,:,2)) - alpha*log(image(:,:,3)) - (1-alpha)*log(image(:,:,1));

%Assume elements in JAVA are stored in three 2D arrays (3 planes): R, G, B
%For example: double[][] R = new double[384][512];
%In Matlab 3 planes are:
R = image(:,:,1);
G = image(:,:,2);
B = image(:,:,3);
%II_image = 0.5 + log(G) - alpha*log(B) - (1-alpha)*log(R);
II_image = zeros(size(R));

%Equivalent for loop (simple to implement in JAVA):
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
image_width = size(image, 2);
image_height = size(image, 1);
for y = 1:image_height %Iterate rows, In JAVA: for(y = 0; y < image_height; y++)
    for x = 1:image_width %Iterate columns, In JAVA: for(x = 0; x < image_width; x++)
        r = R(y, x); %In JAVA: double r = R[y][x];
        g = G(y, x);
        b = B(y, x);

        p = 0.5 + log(g) - alpha*log(b) - (1.0-alpha)*log(r);

        II_image(y, x) = p;
    end
end

%Display ii_image
figure;imshow(ii_image, []);impixelinfo;title('ii\_image');

%Show difference (for debugging):
%figure;imshow(ii_image - II_image, []);impixelinfo

%Display minimum and maximum - values are not valid as pixel values in JAVA.
disp(['min(ii_image) = ', num2str(min(ii_image(:)))]);
disp(['max(ii_image) = ', num2str(max(ii_image(:)))]);


%Convert II_image range to [0, 1]
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
%Find minimum and maximum (in JAVA you can do it inside the loop).
lo = min(II_image(:));
hi = max(II_image(:));

%Apply linear transformation:
II_image = (II_image - lo) / (hi - lo);

figure;imshow(II_image, []);impixelinfo;title('II\_image');
%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

我希望它可以帮助您实现Java。

Answer 2

根据here，您可以在Java中找到很多矩阵库。我建议您选择EJML将逻辑转换为Java。

在Java-照明不变式中实现MATLAB代码

2 个答案: