DISPLAY RED, GREEN & BLUE COMPONENTS OF RGB IMAGE

Hello, I want to display 3 images of red, blue & green component. I don't want to display the GRAYSCALE images. I tried following code:

X-imread('Hello.jpg');
R = X(:,:,1);
image(R), colormap([[0:1/255:1]', zeros(256,1), zeros(256,1)]), colorbar;

%Green Component
G = X(:,:,2);
figure;
image(G), colormap([zeros(256,1),[0:1/255:1]', zeros(256,1)]), colorbar;

%Blue component
B = X(:,:,3);
figure;
image(B), colormap([zeros(256,1), zeros(256,1), [0:1/255:1]']), colorbar;

but it gives me 3 images with background as Red, green & blue.. How can I display only Red component of RGB image [No Grayscales]

Thanks

[Andres Soto]

Try () instead of [] there [0:1/255:1]

[Walter Roberson]

@Andres Soto

A = [0:1/255:1];
B = (0:1/255:1);

isequal(A, B)

ans = logical
   1

The line

A = [0:1/255:1];

to MATLAB means the same thing as

temporary = 0:1/255:1;
A = horzcat(temporary);
clear temporary

but horzcat() of a single variable returns the same thing as the input (but after having taken a little bit of time), so the functionality is the same as

A = 0:1/255:1;

but taking slightly more time.

There are differences between using () and [] brackets. For example,

[1 -2]

ans = 1×2

1 -2

(1 -2)

ans = -1

That is, inside [], in some combinations of spacing, the space can indicate end of an expression and beginning of the next element.

Answer 1

[Walter Roberson]

X-imread('Hello.jpg');
R = X
R(:,:,2:3) = 0;
image(R);
pause(5);
G = X;
G(:,:,[1 3]) = 0;
image(G);
pause(5);
B = X;
B(:,:,1:2) = 0;
image(B);
pause(5);

[kranti kumar kuppili]

PLEASE WRITE REVERSE PROCESS

[Walter Roberson]

kranti kumar kuppili : what would the inputs be?

[DGM]

To answer the "reverse process" question:

% assume that this is the "forward process"
X = imread('peppers.png');

R = X;
R(:,:,2:3) = 0;

G = X;
G(:,:,[1 3]) = 0;

B = X;
B(:,:,1:2) = 0;

montage({R G B},'size',[1 3]);

% now you have three RGB images called R,G, and B
% you could reassemble them directly:
RGB1 = cat(3,R(:,:,1),G(:,:,2),B(:,:,3));

Answer 2

[Priyanka Johri]

x = imread('Hello.jpg');

figure, imshow(x(:,:,1)); % Red component

figure, imshow(x(:,:,2)); % Green component

figure, imshow(x(:,:,3)); % Blue component

% Is this what you required?

[Ali Ibrahim]

Hi .. Im trying to extract the digital numbers from the three color planes--red, green, blue .. can you help?

[Image Analyst]

See attached demo.

[Ali Ibrahim]

That's perfect.. can you please tell me how to change the picture of the football to my image ? which part I should change? Thanks .. I am so happy!

[Image Analyst]

Replace this line:

imagesFolder = fileparts(which('cameraman.tif')); % Determine where demo folder is (works with all versions).

with this line

imagesFolder = 'D:/alis images';

or wherever your images live.

[Arooj Siddique]

These commands are showing red, green and blue component in black and white color. Is there any way to show colors?

[Walter Roberson]

My Answer https://www.mathworks.com/matlabcentral/answers/35499-display-red-green-blue-components-of-rgb-image#answer_44462 shows them in color.

[abdelatti errokhsy]

please how to work this code styb by stybe

[Image Analyst]

@abdelatti errokhsy, What does "styb by stybe" mean? I have no idea what a styb or stybe is.

[Walter Roberson]

I have a suspicion that they are asking for a line by line explanation of the code.

Answer 3

[Image Analyst]

Not sure what you want. I guess my first answer would be to just not display the green and blue components and that would then "display only Red component." But I don't know what you mean when you say "No Grayscales." The red channel, or any color channel is simply a numerical array, and that is normally displayed as gray scale, though you can apply a pseudocolor look up table (colormap) like you did to make it appear in any tint or even combination of many different colors. But you don't want the red channel to appear red, like you're doing now, and you don't want it to appear in gray scale, so what do you want?

[LOKESH]

I mean to to say that when I separate R, G & B components I get three grayscales images. But I need them in color. When I use the above code I get Color images not perfectly as R, G & B but it looks that its background is changed from Red, green & blue.

[Image Analyst]

I'm still not sure what you want. Yes, they are grayscale images but you pseudocolored them to be red, green, and blue. Those are colors and you say you need them in color so I'm confused. Do you want them each as a 3D true color image and not as an indexed grayscale image with its applied colormap? If so, just have the other colorplanes be all zeros :

redImage = rgbImage

redImage(:,:,2:3) = 0; % Set G and B to zeros.

Similarly for the other two colors. Or do it this way:

zeroImage = zeros(size(rgbImage(:,:,2)), 'uint8');

greenImage = cat(3, zeroImage , rgbImage(:,:,2), zeroImage);

But I'm just really guessing since I don't know what you want.

I don't know what "not perfectly" means and I don't know what you're calling "its background". What is background and what is foreground? Perhaps you need to upload your Hello.jpg image.

[Prabhjot Kaur]

I think what he is probably looking for is an output image that shows only only red components of the original image when red channel is applied/extracted from the original image. Likewise for the other two colors.

[Image Analyst]

And Walter and I gave him 2 different ways of achieving that, one by showing an RGB image with just the desired color channel in there, and another method by showing the color channels and using the appropriate colormap.

[Ali Ibrahim]

Hi .. Im trying to extract the digital numbers from the three color planes--red, green, blue .. can you help?

[Walter Roberson]

Do you mean Optical Character Recognition?

[Ali Ibrahim]

I have a photo, and im trying to extract the digital numbers from the three color planes--red, green, blue--and calculate the following indices..VARI = (Green-Red)/(Green+Red-Blue).. GCC = G/(G+R+B) Can you help?

[Walter Roberson]

I do not know if I can help. What does the photo look like?

[Ali Ibrahim]

Like attached .. I just want to extract the digital numbers from the three color planes--red, green, blue

[Image Analyst]

Nothing is attached to your message. See attached demo to see if that helps.

[srikantanss ss]

its awesome simple and great idea ! thank you... srikantan,dehradun,india

[Moe Makki]

@Image Analyst how do i scan pixels of an image and then remove green and blue components if redValue is above 200

[Image Analyst]

@Moe Makki, I answered that in your main question:

https://www.mathworks.com/matlabcentral/answers/836838-how-do-i-scan-pixel-from-an-rgb-image-and-then-if-red-value-is-higher-than-200-show-red-only-and-if#answer_706028

Answer 4

[Shatha Ali.]

i=imread('6.jpg');
red= i(:,:,1);
green=i(:,:,2);
blue=i(:,:,3);
black=i(:,:,0:0:0);
white=i(:,:,1:1:1);
black=zeros(size(i,1),size(i,2),'unit8');
just_red=cat(3,red,black,black);
just_green=cat(3,black,green,black);
just_blue=cat(3,black,black,blue);
just_black=cat(3,black,black,black);
just_white=cat(3,white,white,white);
picture(3,2,1),imshow(i);
picture(3,2,2),imshow(just_red);
picture(3,2,3),imshow(just_green);
picture(3,2,4),imshow(just_blue);
picture(3,2,5),imshow(just_black);
picture(3,2,6),imshow(just_white);

Answer 5

[Dayangku Nur Faizah Pengiran Mohamad]

B = X(:,:,3);
figure;
image(B), colormap([zeros(256,1), zeros(256,1), [0:1/255:1]']), imwrite(B,colormap,'blueHello.jpg');

Hope this will helps you.