I am converting RGB to YCBCR image but reverse is not working.

I want to convert RGB image to YCBCR by using rgb2ycbcr, it is working but when I am using ycbcr2rgb to get back image then it is now converting properly.

[Simon Chan]

Do you mean the function is not working which cannot generate an image for you? Or the generated RGB image has pixel values which are not exactly the same as the original RGB image?

[Balkar Singh]

You are right, pixel value are not exactly the same as the orginal value.

Answer 1

[Walter Roberson]

The below images would show color if there was notable difference between the original image and the reconstructed image. But there isn't -- the maximum change during the reconstruction process is 2 out of 256.

imgrgb = imread('flamingos.jpg');
imgy = rgb2ycbcr(imgrgb);
imgrgb2 = ycbcr2rgb(imgy);

max(abs(double(imgrgb) - double(imgrgb2)),[],'all')

ans = 2

imshowpair(imgrgb(:,:,1), imgrgb2(:,:,1));

imshowpair(imgrgb(:,:,2), imgrgb2(:,:,2));

imshowpair(imgrgb(:,:,3), imgrgb2(:,:,3));

[Balkar Singh]

But due to some loss, I am not able to extract the watermark image properly.

[Walter Roberson]

Then you need to use a more robust watermark.

Answer 2

[Balkar Singh]

You are right, pixel value are not exactly the same as the orginal value.

[Image Analyst]

Some rounding errors will occur during a round trip when you are converting integers to floating point and then back again.

[Balkar Singh]

Please consider the example given by Walter Roberson, what i have to add in that example.