how to mask the image and keep only one color "green channel"?

Hi, here I have one photo and the code, please anyone help me to fix my code, I want to mask the binary with the RGB.

% Extract the individual red, green and blue color channel

redChannel = hasilcontrast(:,:,1);

greenChannel = hasilcontrast(:,:,2);

blueChannel = hasilcontrast(:,:,3);

% Create the mask

mask = cast(green, class(hasilcontrast));

redmask = redChannel.*mask;

greenmask = greenChannel.*mask;

bluemask = blueChannel.*mask;

% segmentasi

maskRGBimage = cat(3,redmask, greenmask, bluemask);

I not get the result, how I do to show the image. please help me sir

[Akira Agata]

I'm not clearly understanding what you would like to do in your code. But I suppose what you want would be something like this. Am I correct??

[Oman Wisni]

Yes, I want like that, can you show me the code? I'm sorry, I confused how I explain, but your answer is right

[Oman Wisni]

How you get the maskedRGB? Do you multiply multiply the original image with mask?

Answer 1

[Image Analyst]

I've done this so many times I lost track, and some time back decided to make a demo of it. Leaf, fruit, money, handwriting, leaf, fruit, money, handwriting, everyone wants to segment a leaf, fruit, money, or handwriting. Click on the tag "leaf" on the right hand side of this page. See attached demo.

[Oman Wisni]

sorry sir and thanks for the answer, but I'm not use that method..

please see this picture, I make like this but no saturation, only green channel.

[Image Analyst]

Because the image is so contrasty, there are many color spaces that you could threshold. If you want to convert to hsv color space and then use the saturation channel, or value channel to threshold, you could do that too. I didn't know you had a preference so I just gave one way that works.

[Oman Wisni]

yes sir, that picture only example. I only using green channel for thresholding then the result of thresholding I using for mask to RGBchannel. But I have error in my program, so I need help how to creating code for masking and later give me result only green

[Image Analyst]

Well post your code and I can make it into my code. What exactly in my code don't you like? That it's doing the segmentation in RGB color space? Did you try the Color Thresholder app on the Apps tab of the tool ribbon?

[Oman Wisni]

yes sir, I want to masking binnary image with RGB image, I masking every channel in mask, Greenmask, Bluemask then I recombine again to RGB. Can you make the code Global Thresholding to get binnary image then masking ?

Not, I'm not use the Color Thresholder app. I make manual code

[Image Analyst]

I thought you wanted it done in HSV color space, nor red Green Blue color space. Which is it?

[Oman Wisni]

Only in red, green, blue color space. The figure I posted use HSV it just the example.

I only want in RGB color, threshold using global Otsu's Thresholding then masking

[Image Analyst]

So, simply replace

mask = blueChannel > 200;

by

mask = imbinarize(blueChannel); % Otsu thresholding.

and it works fine. See attached.

[Oman Wisni]

Yes sir, thank you very much

[Image Analyst]

If you get holes in your leaf, and don't want them, you can call

mask = imfill(mask, 'holes');

[Oman Wisni]

Yes sir, thanks.. Sir, the value 200, is that default value?

Answer 2

[Akira Agata]

Hi Oman-san,

Thank you for your prompt reply. The following is the code to generate the posted figure. I hope this will be some help for your research!

% Read the image
I = imread('base1.bmp');

% Create a mask based on a green channel of the image
BWmask = ~imbinarize(I(:,:,2));
BWmask = imfill(BWmask,'holes');

% Create a masked RGB image
Imasked = immultiply(I,repmat(BWmask,[1 1 3]));

% Show the results
figure
subplot(2,2,1)
imshow(I)
title('Original','FontSize',12)
subplot(2,2,2)
imshow(BWmask)
title('Mask','FontSize',12)
subplot(2,2,3)
imshow(Imasked)
title('Masked RGB','FontSize',12)

[Oman Wisni]

thanks sir, you only keep green channel, I think all channel have been mask than you recombine again..

Im sorry sir, after I see your code that is not I mean. Like my code in above I want mask all channel in RGB channel, I get the mask every channel then I combine again. for mask I using multiply, and for recombine I using maskRGBimage = cat(3,redmask, greenmask, bluemask); and the result only keep green channel, I already upload the picture index.jpg, I want like that but no saturation channel.