Image matrix codding with LDPC channel coding

I need to MATLAB function to convert an image into matrix and encode it with LDPC codding then need to modulate it with PSK modulation

Answer 1

[Debadipto]

Hi @Dinushka,

To convert an image into matrix and encode it with LDPC coding followed by modulating it with PSK, you can follow the below steps:

1. Conversion of image to matrix: MATLAB can directly read images into matrices using the imread function. For simplicity, we'll convert the image to grayscale, which can be easily represented as a 2D matrix.
2. LDPC Encoding: You can use MATLAB's built-in functions to create an LDPC encoder. The comm.LDPCEncoder system object can be used for this purpose. You'll need to specify or generate an LDPC parity-check matrix.
3. PSK Modulation: For PSK modulation, you can use the comm.PSKModulator system object. The modulation order (e.g., 2 for BPSK, 4 for QPSK) will be one of the parameters.

Here's an example MATLAB function achieving the same, that you can refer to:

function pskModulatedSignal = imageToPSKModulatedSignal(imagePath, ldpcParityCheckMatrix, modulationOrder)

% Step 1: Convert Image to Matrix

img = imread(imagePath);

imgGray = rgb2gray(img); % Convert to grayscale if it's a color image

imgVector = imgGray(:); % Convert the 2D image to a 1D vector for processing

% Convert image pixel values to binary

imgBinary = de2bi(imgVector, 8, 'left-msb'); % Assuming 8 bits per pixel

imgBinaryVector = imgBinary(:); % Convert to a vector

% Step 2: LDPC Encoding

ldpcEncoder = comm.LDPCEncoder('ParityCheckMatrix', ldpcParityCheckMatrix);

encodedData = step(ldpcEncoder, imgBinaryVector);

% Step 3: PSK Modulation

pskModulator = comm.PSKModulator(modulationOrder, 'BitInput', true);

pskModulatedSignal = step(pskModulator, encodedData);

% Return the PSK modulated signal

end

This function is a basic implementation. Depending on your specific requirements (e.g., handling color images, specific LDPC code rates, or PSK modulation features), you might need to make adjustments. Also, error checking and input validation are recommended for a more robust implementation.

Hope this helps!

[Dinushka]

in the provided code, is it possible to reconstruct the color image

[Debadipto]

For reconstructing the color image from the PSK modulated signal, you would need to perform the inverse operations of each step in the process. This includes PSK demodulation, LDPC decoding, and converting the binary data back into an image format.