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How to make image background white?

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Zara Khan
Zara Khan on 24 Dec 2019
Commented: Zara Khan on 28 Dec 2019
I have a binary image. I want to make the background white keeping the black straight lines intact.I mean those lines which intersecting image objects will remain intact. Picture has attached.

Accepted Answer

Jeff E
Jeff E on 24 Dec 2019
I would start by closing in small gaps to get a solid hand.
imgin_close = imclose(imgin, strel('square', 3));
Then I would find the overlap between that solid hand, and the inverse of the original image, leaving me with just white lines on a black background. You may have some additional noise around the edges of the hand. The could be filtered out with something like bwareaopen, depending on your application.
imgin_lines = imgin_close & ~imgin;
imgin_lines = bwareaopen(imgin_lines, 3);
I would then take the inverse of that image to get just the black lines.
imgout = ~imgin_lines;
  5 Comments
Image Analyst
Image Analyst on 26 Dec 2019
Zara, I'm not sure what your question means. What do you want to give black lines "to"? What other colours are there that should receive/get black lines?
Or do you mean "how can I display the black lines in a variety of colors?" If that is what you mean, then label the lines-only image and call label2rgb().
% Label each line with a unique ID number.
labeledImage = bwlabel(imgin_lines)
% Let's assign each blob a different color to visually show the user the distinct blobs.
coloredLabels = label2rgb (labeledImage, 'hsv', 'k', 'shuffle'); % pseudo random color labels
% coloredLabels is an RGB image. We could have applied a colormap instead (but only with R2014b and later)
imshow(coloredLabels);
Zara Khan
Zara Khan on 28 Dec 2019
Image Analyst: Wonderful. Exactly this is what I was asking for.

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