WHY IN GRAY IMAGE HAVE RGB??

Dear Sir,

I have image below as gray image. The index value (439) indicate as gray level. But what I dont understand is, why the RGB value on it image?

Because as I know this is gray image.

The set of my images as attached.

Anyone can help me to explained to me?

Answer 1

[Image Analyst]

It's an RGB image. It's just that the red channel, the green channel, and the blue channel are all the same so it appears as gray scale. You can convert it to grayscale by taking any one of the color channels:

grayImage = rgbImage(:, :, 1);

[mohd akmal masud]

But I got error

Unrecognized function or variable 'rgbImage'.

[Image Analyst]

When I actually opened the dicom file I found out it's 256x256x1x142 so it's a 3-D image. You can do this:

fileName = 'I-13125610N1.dcm'
rgbImage = dicomread(fileName);
imageSize = size(rgbImage)
for slice = 1 : imageSize(4)
    grayImage = rgbImage(:, :, 1, slice);
    imshow(grayImage, []);
    caption = sprintf('#%d of %d', slice, imageSize(4));
    title(caption, 'FontSize', 14);
    drawnow;
end

to display them all.