how to segment hand from an image with non uniform lighting?

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H
H 2014년 7월 12일
댓글: Image Analyst 2020년 11월 14일
I'm trying to segment the hand from the image but due to the non uniform lighting the result come out like this
the result in uniform lighting
how to solve this problem?

채택된 답변

Image Analyst
Image Analyst 2014년 7월 12일
Just fix the lighting - it's so simple! It's almost always easier to prevent the problem than to fix it with software and that is definitely the case here.
If you don't want to get the job done in the most sensible, easy, straightforward, and best way (by fixing the illumination), then there are more complicated ways that you can do it, but you have to make some assumptions, like on the size of the hand, or its color, or on the smoothness of the background, or things like that. Some fix you make for one situation might not work for another. Like if you have that picture and then another where the hand is in front of a flesh colored screen, or a screen with a paisley background - those may all take different algorithms.
For what it's worth, I attach a background correction demo.
  댓글 수: 4
Image Analyst
Image Analyst 2014년 7월 14일
If you know your background is always neutral colored and your hands are not, then you can convert to hsv color space and threshold for reddish pixels. See my demo : http://www.mathworks.com/matlabcentral/fileexchange/28512-simple-color-detection-by-hue

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추가 답변(3개)

Laila Kazemi
Laila Kazemi 2014년 7월 12일
You need adaptive threshold since the background changes. I have not yet found a good code in matlab for this. you might have to find your own algorithm and code it.
  댓글 수: 1
H
H 2014년 7월 14일
Here I used graythresh(). but I also tried many different levels for the shareholding other than this level but it didn't work. I also used diifferent segmentation techniques and the result is the same. I think the first step should be fixing the illumination.

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Prasad Kalane
Prasad Kalane 2014년 7월 14일
% Do some image illumination correction.
background = imopen(I,strel('disk',15));
I = I - backgroundbackground
I = imadjust(I);
% level = graythresh(I);
bw = im2bw(I,0.3*level);

Milion Negewo
Milion Negewo 2020년 11월 14일
background = imopen(I,strel('disk',15));
I = I - backgroundbackground
I = imadjust(I);
% level = graythresh(I);
bw = im2bw(I,0.3*level);
  댓글 수: 1
Image Analyst
Image Analyst 2020년 11월 14일
Here is your algorithm:
I = imread('hands.png');
% Display original image.
subplot(2, 3, 1);
imshow(I);
title('Original Image');
% Convert to gray scale so we can call imopen().
I = rgb2gray(I);
% Display original image.
subplot(2, 3, 2);
imshow(I);
title('Gray Scale Image');
background = imopen(I, strel('disk',15));
% Display image.
subplot(2, 3, 3);
imshow(background);
title('Background Image');
I = mat2gray(double(I) - double(background));
I = imadjust(I);
% Display image.
subplot(2, 3, 4);
imshow(I);
title('Background Subtracted Image');
level = graythresh(I);
bw = im2bw(I, 0.3*level);
% Display image.
subplot(2, 3, 5:6);
imshow(bw);
title('Final Binary Image');
The final image doesn't look so good. I think you need to work on it some more.

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