MATLAB Answers

convert binary image to RGB image

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fereshte on 16 Jun 2014
Commented: Image Analyst on 28 Sep 2015
how convert binary image to RGB image? my original image and binary image attached. thanks


fereshte on 16 Jun 2014
i use this code but failed!
RGB = cat(3, binaryImage, binaryImage, binaryImage);
Joseph Cheng
Joseph Cheng on 16 Jun 2014
What failed? code seems fine. What are you looking for as a result?
fereshte on 17 Jun 2014
same binary image but with main colors.i want to processing on colored extraction parts and dont need to binary image same heel image i want convert binary image to colored image

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Answers (2)

Image Analyst
Image Analyst on 17 Jun 2014
Your code is almost okay but not quite robust enough. And you didn't scale it by multiplying by 255 so that you can see it (otherwise it will have values of just 0 or 1 which will be so dark as to be virtually invisible). If you're going to display an RGB image like that the image has to be a uint8 image in the range of 0-255. So a more robust way to do it is this (untested):
baseFileName = 'binary.bmp';
fullfileName = fullfile(pwd, baseFileName);
if ~exist(fullFileName, 'file')
message = sprintf('Image file %s was not found!', fullFileName);
binaryImage = imread(fullFileName);
[rows, columns, numberOfColorChannels] = size(binaryImage)
maxValue = max(binaryImage(:))
minValue = min(binaryImage(:))
if numberOfColorChannels > 1 || minValue < 0 || maxValue > 1
message = sprintf('Image is not a binary Image!');
grayImage = 255 * uint8(binaryImage);
RGB = cat(3, grayImage, grayImage, grayImage);
Try that and tell me how it goes.


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Image Analyst
Image Analyst on 18 Jun 2014
A true binary image is a logical image that can have values of true or false. You probably have an image that you think is binary because it has pixels that appear only black or white. This is possible if the image is floating point with values of 0 and 1, or grayscale with values of 0 and 1 if you used imshow(grayImage, []), or grayscale with values of 0 and 255 if you used imshow(grayImage), or color with RGB values of [0,0,0] and [255,255,255]. I suspect, since it's a BMP image, that you have the last case - a color image. You can convert to a binary image (I think I told you this in your duplicate question already):
binaryImage = binaryImage(:,:,2) > 128;
Note that in the above fix, binaryImage started out as an RGB image but we extracted the green channel (which looks the same as the other two color channels) and thresholded it. Now binaryImage is of type "logical" and have values of true and false so it is a true binary image now.
Muthu Annamalai
Muthu Annamalai on 28 Sep 2015
Maybe it would help if @fereshte can upload the BMP image in question to the forums ? That way you can reduce some of the back-n-forth and known limitations of MATLAB code from the answers forum
Image Analyst
Image Analyst on 28 Sep 2015
The images were uploaded, back on June 17th. There's no more back and forth - I guess it's not a problem for him anymore (3 months later).

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Youssef  Khmou
Youssef Khmou on 16 Jun 2014
Edited: Youssef Khmou on 16 Jun 2014
The technique you used failed because the function does not provide a visualization of three dimensional logical matrices, besides i do not think the binary to RGB transformation is possible because there are not enough information about the channels, thus RGB to binary is possible .


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