removing background of the color picture

조회 수: 12 (최근 30일)
Malini Bakthavatchalam
Malini Bakthavatchalam 2020년 5월 3일
댓글: Malini Bakthavatchalam 2020년 5월 3일
Hi, i am working on a project, were I have to calculate the pixels inside the object only, my image contains a human face and a white background, all I want to do is to remove the background and save only the face of the person and calculate histograms from the face pixels only for my project. I have tried a thresholding method, so that kind of removes background and gives a black color as background. And i have used imwrite function to save the image and use it for further analysis. but the problem, I am not sure whether I am calculating only from the face pixels or the entire image including black as background. I am attaching my code here. kindly help me clear my doubt
%%threshold the image
I = imread('facergbimg.jpg');
[BW rgb]= createMaskbcgremoval(I); this is a bckground removal code done with the use of image proccessing color threshold from the math works.
% % save the image in a folder
% % work with the background removal image working only with face pixels
% % separate image into 3 channels
img = imread('file.jpg'); % Read image
red = img(:,:,1); % Red channel
green = img(:,:,2); % Green channel
blue = img(:,:,3); % Blue channel
a = zeros(size(img, 1), size(img, 2));
just_red = cat(3, red, a, a);
just_green = cat(3, a, green, a);
just_blue = cat(3, a, a, blue);
back_to_original_img = cat(3, red, green, blue);
figure, imshow(img), title('Original image')
figure, imshow(just_red), title('Red channel'),imwrite(just_red,'just_red.jpg')
figure, imshow(just_green), title('Green channel'),imwrite(just_green,'just_green.jpg')
figure, imshow(just_blue), title('Blue channel'),imwrite(just_blue,'just_blue.jpg')
%% now split the histogram
G =imread('just_green.jpg');
K_median_cal= reshape(G,[],1);
total_median = mean(K_median_cal);
K(G<total_median) = G(G<total_median);
P(G>total_median) = G(G>total_median);
K = uint8(double(total_median) .* ones(size(G)));
P = uint8(double(total_median) .* ones(size(G)));
for i=1:length(G(:,1))
for j=1:length(G(1,:))
if G(i,j)<total_median
title('upper rectified');
ylim([0 10000])
ylim([0 10000])

채택된 답변

Image Analyst
Image Analyst 2020년 5월 3일
"whether I am calculating only from the face pixels or the entire image including black as background." <== you are calculating total_median from G, which is the green channel of the background-removed image that you wrote to disk. I must say though that it looks like a very roundabout way of coding, like why write the rgb matrix out to disk only to read it back in as img? Etc.
  댓글 수: 3
Image Analyst
Image Analyst 2020년 5월 3일
Not sure what you want but to compute the median of each color channel, you'd do this:
medianR = median(red);
medianG = median(green);
medianB = median(blue);
I can't figure out how you're computing total_median or what it even means.
And I don't know exactly what "see how the transmittion is happening from black to each color channel" means. Do you want code to zoom in to see the black-to-colored region in more detail? If so, see the attached zooming demo.
Malini Bakthavatchalam
Malini Bakthavatchalam 2020년 5월 3일
hi professor,
I think I wasnt clear enough , all i want to do, for example take a green channel find the median (for ex if the median of the image histogram is 214, i need to split the histogram into half below 214 and above 214 and create the image with the values less than 214(lower rectified image) and above 214(upper rectified image). i want to know how the less than median and above the median value image looks like ..
so for that this formula is the optimization formula .
K(G<total_median) = G(G<total_median);- create image with this
P(G>total_median) = G(G>total_median);& create an image with this. so by the end of it i should have three images one is the original and other two are lower and higher rectified images. this is for an color illusion study.

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