How do you change pixels in an image?

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Isee You
Isee You 2012-2-19
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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回答（3 个）

Jan
Jan 2012-2-19
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
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.

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Isee You
Isee You 2012-2-21
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
Isee You 2012-2-22
no the small dark part inside the liver .
Image Analyst
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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Isee You
Isee You 2012-2-22
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
you can see this file to understand what i mean about (x,y)
http://www.mediafire.com/?el5535xp5q3eg8l

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