How do you change pixels in an image?

Question

Isee You 2012-2-19

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https://ww2.mathworks.cn/matlabcentral/answers/29613-how-do-you-change-pixels-in-an-image

编辑： dpb 2013-10-19

i want to get the difference between two pixel and then i want to chang pixel value to become yellow . please help!!!!

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Answer 1

Jan 2012-2-19

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https://ww2.mathworks.cn/matlabcentral/answers/29613-how-do-you-change-pixels-in-an-image#answer_37981

在 MATLAB Online 中打开

The question is not clear. Are you talking about RGB images? Which pixel should be set to yellow? Perhaps this helps:

image1 = rand(100,100,3);
image2 = rand(100,100,3);
diffPixel = image1(51,67,:) - image2(51,67,:);
image1(51,67,:) = [1, 1, 0];

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Image Analyst 2012-2-19

Try this first: http://www.mathworks.com/matlabcentral/answers/6200-tutorial-how-to-ask-a-question-on-answers-and-get-a-fast-answer

Then come back and tell us which two pixels you want to take the difference of and which pixels you want to set to yellow. Do you want to convert your gray scale image to RGB color now? Or do you want to apply a colormap? Do you have any photos that you uploaded to tinypic.com that you can show us? You need to put some work into your question, more than 10 seconds anyway. Because as I see it, Jan has answered your question. If not, you need to explain why.

Isee You 2012-2-24

any help

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Answer 2

Isee You 2012-2-21

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https://ww2.mathworks.cn/matlabcentral/answers/29613-how-do-you-change-pixels-in-an-image#answer_38253

OK i will try as possible. my project is locate dark part in this image and isolate it

http://www.mediafire.com/i/?g17fhg01c700h7u

i read this sheet

http://www.mediafire.com/?5b2pyo2m1qr2pkl

you can see in page (5) figure (a) the algorithm i work in . This algorithm is so close to this http://www.mathworks.com/matlabcentral/answers/26697-how-to-calculate-gradient-between-the-currently-processed-point-x-y-and-its-neighboring-point-in-o

ok.

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Isee You 2012-2-22

no the small dark part inside the liver .

Image Analyst 2012-2-22

Give us some code to start with. I don't want to develop the whole app from scratch for you.

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Answer 3

Isee You 2012-2-22

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https://ww2.mathworks.cn/matlabcentral/answers/29613-how-do-you-change-pixels-in-an-image#answer_38385

在 MATLAB Online 中打开

i isolate the liver and then i use this code to get the difference between the pixels (x.jpg)is my image of liver only.

function test4_loop(img) 
  a = imread('x,jpg');
    [xx,yy]=size(a);
    for x=1:(xx-3)
     for y=1:(yy-3)
        z1=impixel (a,x,y)
        z2=impixel (a,x,(y+1));
        z3=impixel (a,x,(y+2));
        z4=impixel (a,(x+1),(y));
        z5=impixel (a,(x+1),(y+1));
        z6=impixel (a,(x+1),(y+2));
        z7=impixel (a,(x+2),(y));
        z8=impixel (a,(x+2),(y+1));
        z9=impixel (a,(x+2),(y+2));
        z=[z1 z2 z3;
      z4 z5 z6;
      z7 z8 z9];
    avg=mean2(z);
      do(avg,x,y);
     end   
    end
function do(mean,x,y)
a=imread('x.jpg');
%north eset
while x>0 && y>0
    r=mean-a(x-1,y-1);
    x=x-1;
    y=y-1;
end
%north
while x>0 && y>0
    r=mean-a(x-1,y+1);
    x=x-1;
end
%north west
while x>0 && y>0
    r=mean-a(x-1,y+2);
    x=x-1;
    y=y+1;
end
%west
while x>0 && y>0
    r=mean-a(x+1,y+3);
    y=y+1;
end
%north west
while x>0 && y>0
    r=mean-a(x+3,y+3);
    x=x+1;
    y=y+1;
end
%norht
while x>0 && y>0
    r=mean-a(x+3,y+1);
    x=x-1;
    y=y-1;
end
%north east
while x>0 && y>0
    r=mean-a(x+3,y-1);
    x=x+1;
    y=y-1;
end
%eset
while x>0 && y>0
    r=mean-a(x+1,y-1);
      y=y-1;
end