how can i add noise to a picture with snr= 5dB?

how can i add noise to a picture with snr= 5dB?

Answer 1

[HSIN-YUAN CHEN]

Hi,

To add noise to an image with a specific Signal-to-Noise Ratio (SNR) in MATLAB:

% Load and convert image to double
I = double(imread('path_to_your_image.jpg'));
% Compute signal power and calculate noise power for desired SNR
P_signal = var(I(:));
P_noise = P_signal / 10^(5 / 10);  % 5 dB SNR
% Generate noise and add it to the image
noise = sqrt(P_noise) * randn(size(I));
I_noisy = I + noise;
% Display the noisy image
imshow(uint8(I_noisy));

Code assumes grayscale, no pixel checks; adjust as needed.

Hope this helps.