将图像中的特定颜色更改为黑色

Question

我希望我的程序将 coloredChips.png 中用户输入的颜色更改为黑色。我该怎么做？我试过了，但是失败了。

clc;
close all;
clear;
originalImage = imread('coloredChips.png'); % Load original ColoredChips.png image
[rows, columns, numberOfColorBands] = size(originalImage); % Get the dimensions of the image
% Display the original images
subplot(2,1,1);
imshow(originalImage);
% Extract the individual red, green, and blue color channels.
redChannel = originalImage(:, :, 1);
greenChannel = originalImage(:, :, 2);
blueChannel = originalImage(:, :, 3);
black = redChannel == 0 & greenChannel  == 0 & blueChannel  == 0;
color = input("Enter color to remove(RED,GREEN,BLUE): ", 's'); % taking input from user
for row = 1 : rows %iterating over each pizel of image
    for column = 1 : columns
        if color == "RED"
            originalImage(black) = 0; % if input is red we'll make red channel value for this pixel to 0
        elseif color == "GREEN"
            originalImage(black) = 0; % if input is green we'll make red channel value for this pixel to 0
        else
            originalImage(black) = 0; % if input is green we'll make red channel value for this pixel to 0
        end
    end
end
rgb = cat(3, redChannel, greenChannel, blueChannel);
subplot(2,1,2);
imshow(rgb);

如您所见，我输入了红色，但图像仍然是红色，而不是黑色：

Answer 1

您的代码的第一个问题是，在您的 for 循环中，您更改了 originalImage 而不是您的红色、绿色、蓝色通道。其次，您不使用迭代参数，这意味着您实际上没有设置相应的像素，实际上在您的 for 循环中，您将黑色像素设置为黑色。

下面是我如何解决问题的示例代码。希望这能给你一些指示。

orgImg = imread('image.jpg');

% threshold 
t = 0.5;
colThresUp = t * 255;
colThresLow = (1-t) * 255;

% init color mat
rMat = orgImg(:,:,1);
gMat = orgImg(:,:,2);
bMat = orgImg(:,:,3);

% build an index matrix of all pixels that are above the threshold
% resp. below for the other colors

% TODO depending on user selection - example for RED
idxSelCol = orgImg(:,:,1) > colThresUp & ...
    orgImg(:,:,3) < colThresLow & ... 
    orgImg(:,:,2) < colThresLow;

% set all pixels above the threshold to zero i.e. black
rMat(idxSelCol) = 0;
gMat(idxSelCol) = 0;
bMat(idxSelCol) = 0;

% build new image
modImg = cat(3, rMat,gMat,bMat);

% visualize result
subplot(2,1,1)
imshow(orgImg)

subplot(2,1,2)
imshow(modImg)

将图像中的特定颜色更改为黑色

Change a specific color in an image to black

matlab