如何在Matlab中找到并突出显示图像中最亮的区域? [英] How to find and highlight the brightest region an image in Matlab?

问题描述

亲爱的

我想请您支持.我的目标是找到RGB图像的最亮区域，并在不使用其他工具的情况下突出显示该区域.请在下面查看我的示例.

I would like to kindly ask you for support. My goal is to find the brightest region of the RGB image and highlight it without additional tools. Please see my example below.

rgbImage = imread( 'Zoom1_WhiteImage.png' );
imshow(rgbImage);

[rows, columns, numberOfColorChannels] = size(rgbImage)

[x, y] = meshgrid(1:columns, 1:rows);
% Extract the individual red, green, and blue color channels.
% Need to cast to double or else x and y will be clipped to 255 when we concatenate them.
if numberOfColorChannels == 1
    % Leave as gray scale.
    % Get array listing [r, g, b, x, y].  Using (:) will turn all the 2-D arrays into column vectors.
    output = [rgbImage(:), x(:), y(:)];
else
    redChannel = double(rgbImage(:, :, 1));
    greenChannel = double(rgbImage(:, :, 2));
    blueChannel = double(rgbImage(:, :, 3));
    % Get array listing [r, g, b, x, y].  Using (:) will turn all the 2-D arrays into column vectors.
    output = [redChannel(:), greenChannel(:), blueChannel(:), x(:), y(:)];
end

[rows, columns] = find(rgbImage == 155);
imshow(rgbImage);
hold on

不幸的是，我在如何处理应该覆盖灰色图像的点的图上很挣扎.

Unfortunately, I am struggling with how to proceed with the plot of the points that should overlay the grey image.

请你这么友好，请帮助我完成代码吗?

Would you be so kind and help me to finish the code, please?

推荐答案

我建议您阅读有关MATLAB中逻辑索引的信息-这是一个非常强大的概念，它可以让您跳过大多数尝试做的事情通过展平数组，然后使用 meshgrid 创建单独的索引数组.这是一篇文章，涉及逻辑索引例如在底部.

I'd recommend you read about logical indexing in MATLAB - it's a very powerful concept, and it allows you to skip most of the things you're trying to do by flattening the arrays, and creating separate arrays of indices with meshgrid. Here is an article that addresses logical indexing down at the bottom, for example.

我已经修改并添加到您的代码中，因此它可以使用逻辑索引来完成这项工作.我在R2019b中对此进行了测试.

I've modified and added to your code so it accomplishes the job using logical indexing. I tested this in R2019b.

rgbImage = imread( 'Zoom1_WhiteImage.png' );
imshow(rgbImage);

[rows, columns, numberOfColorChannels] = size(rgbImage)

% This is unnecessary - the 'find' command will generate the indices 
%   without you preparing a matrix of them:
% [x, y] = meshgrid(1:columns, 1:rows);   

if numberOfColorChannels == 1
    % No need to flatten the image, or combine it with indices:
    %output = [rgbImage(:), x(:), y(:)];

    brightness = rgbImage;  % For a 1 channel image, brightness is the same as the original pixel value.

else
%     redChannel = double(rgbImage(:, :, 1));
%     greenChannel = double(rgbImage(:, :, 2));
%     blueChannel = double(rgbImage(:, :, 3));
    % Get array listing [r, g, b, x, y].  Using (:) will turn all the 2-D arrays into column vectors.
%     output = [redChannel(:), greenChannel(:), blueChannel(:), x(:), y(:)];

    % For an RGB image, the brightness can be estimated in various ways, here's one standard formula: 
    brightness = (0.2126*rgbImage(:, :, 1) + 0.7152*rgbImage(:, :, 2) + 0.0722*rgbImage(:, :, 3));
end

% Establish a brightness threshold - pixels brighter than this value will
% be highlighted
threshold = 215;

% Create a zero-filled mask of equal size to the image to hold the
% information of which pixels met the brightness criterion:
mask = zeros(rows, columns, 'logical');

% Assign "1" to any mask pixels whose corresponding image pixel met the
% brightness criterion:
mask(brightness > threshold) = 1;

figure;
% Overlay and display mask. imoverlay was introduced in R2017, but the 
% syntax has changed a bit, so check the version you're using. You can also
% use imfuse, or imshowpair, or make your own image blending algorithm, 
% depending on how you want it to look.
imshow(imoverlay(rgbImage, mask, 'red'));
hold on

这篇关于如何在Matlab中找到并突出显示图像中最亮的区域?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！