Read and display RGB png/jpg image

Hi,

I need help in reading and displaying RGB png and jpg image. I am using the follwoing code, but imshow is displaying grayscale image only.

original = imread('C:\Users\R\Desktop\Image\image1.png');

original = im2double(original);

imshow(original)

title('Original image')

[Ameer Hamza]

If you open 'image1.png' outside MATLAB, does it show a colored image? Can you attach this image?

[Kiruthiga Sekar]

yes

Answer 1

[Ameer Hamza]

You png file is actually an indexed image with a colormap. You can see it in color using following statements

[img, map] = imread('image.png');
imshow(img, map)

or, you convert it to rgb, you can use ind2rgb()

[img, map] = imread('image.png');
img_rgb = ind2rgb(img, map);
imshow(img_rgb)

[Kiruthiga Sekar]

It is working. Thanks! How can i add noise to such RGB image? Can you please help?

[Ameer Hamza]

I am glad to be of help!!!

See this function: https://www.mathworks.com/help/images/ref/imnoise.html

[Kiruthiga Sekar]

I used imnoise function, after adding it is again displaying the noisy image in grayscale.

[Ameer Hamza]

How did you use imnoise()? Can you show the code?

[Kiruthiga Sekar]

noisyimage = imnoise(original, 'gaussian',0,0.01); % trying to add noise here

and also I am trying to split the noisy image into its individual color channel using the code below and am getting an error

R = noisyRGB(:,:,1);

G = noisyRGB(:,:,2);

B = noisyRGB(:,:,3);

Error:

[Ameer Hamza]

How is the original defined? Is it rgb image of indexed image? Also, is noisyimage and noisyRGB same?

[Image Analyst]

original must be either a gray scale image OR an RGB image. It makes absolutely no sense if original is a indexed image. You MUST convert it to an RGB image first, and then to a gray scale image after that if you want it as gray scale.

[indexedImage, map] = imread('image.png');
% Convert indexed image to RGB true color image.
rgbImage = ind2rgb(indexedImage, map);
% Add noise to the RGB true color image.
noisyRGBImage = imnoise(rgbImage, 'gaussian',0,0.01);
imshow(noisyRGBImage)
% Convert RGB true color image to a gray scale image.
grayImage = rgb2gray(rgbImage); % Do not pass in indexedImage!
% Add noise to the gray scale image.
noisyGrayImage = imnoise(grayImage, 'gaussian',0,0.01);
imshow(noisyGrayImage)