Image to audio using matlab

Hi, This is my first time posting here. I've recently been dumped with some of my prof's work. I have to come up with a matlab code to convert an image file in a jpg format and convert it into an audio file. I also want to know how to convert it back to the original image, using the image as the input. My prof wants me to modulate it in BPSK, he doesn't want OFDM or any amplitude modulation. Basically, he explained it to me as : take an image, convert it into an array form, convert array into sine wave, then to audio, transmit it, receive it in another system, get back original image.

I'm not very good in using matlab, please help...

[Walter Roberson]

Please expand on "convert array into sine wave". Is your professor looking for the fft2 coefficients? If so then many of those would have imaginary coefficients, and it is not possible for audio to contain imaginary coefficients.

[Star Strider]

The task seems to me to encode an image, transmit it using BPSK, and decode and reconstruct it at the receiving end.

[Walter Roberson]

It seems to me if that were the task then audio would not have been mentioned.

Sounds to me more like a homework assignment than something a prof would work on, at least not without discussion of number of channels and progressive image encoding techniques and error correction codes...

[Jesús Antonio Cubillos Manrique]

Hi, Can you make it?, It's my project and I don't have idea how make it, if you can help me, I'll thank with you, I hope that you have a good day!

Answer 1

[Image Analyst]

Did anyone even attempt anything? What happened if you did something similar to this:

% Initialization / clean-up code.
clc;    % Clear the command window.
close all;  % Close all figures (except those of imtool.)
clear;  % Erase all existing variables. Or clearvars if you want.
workspace;  % Make sure the workspace panel is showing.
format long g;
format compact;
fontSize = 20;

% Create the filename where we will save the waveform.
folder = pwd;
baseFileName = 'Test_Wave.wav';
fullFileName = fullfile(folder, baseFileName);
fprintf('Full File Name = %s\n', fullFileName);
titleBarCaption = 'Continue?';

% Set up the time axis:
Fs = 8000;
duration = 2; % seconds.
t = 1 : duration * Fs; % 2 seconds

% Set up the period (pitch, frequency):
T = 13; % Constant pitch if you use this.

% Create the maximum amplitude:
Amplitude = 32767;

% Read in an image.
fileName = 'pout.tif';
grayImage = imread(fileName);
% Display the gray scale image.
subplot(2, 2, 1);
imshow(grayImage);
title(fileName, 'FontSize', fontSize);

% Threshold it
binaryImage = imbinarize(grayImage);
% Display the binary image.
subplot(2, 2, 3);
imshow(binaryImage);
title('Binary Image', 'FontSize', fontSize);

% Construct the waveform:
y = int16(Amplitude .* sin(2.*pi.*t./T));
% y = abs(int16(Amplitude .* sin(2.*pi.*x./T)));

% Plot the waveform:
subplot(2, 2, 2);
plot(t, y, 'b-');
title('Original Waveform', 'FontSize', fontSize);
xlabel('Time', 'FontSize', fontSize);
ylabel('Y', 'FontSize', fontSize);
grid on;
% Enlarge figure to full screen.
set(gcf, 'units','normalized','outerposition',[0 0 1 1]);
fprintf('Writing file %s...\n', fullFileName);

% Play the original sound.
player = audioplayer(y, Fs);
play(player);

% Make the binary signal for BPSK the same size as the image.
phase = imresize(binaryImage(:), [length(y), 1]);

% Invert the signal wherever the binary image is 1
y(phase) = -y(phase);

% Plot the waveform:
subplot(2, 2, 4);
plot(t, y, 'b-');
title('Altered Waveform', 'FontSize', fontSize);
xlabel('Time', 'FontSize', fontSize);
ylabel('Y', 'FontSize', fontSize);
grid on;

% Write the waveform to a file:
audiowrite(fullFileName, y, Fs);

promptMessage = sprintf('That was the original sound.\nClick OK to play the altered sound.');
button = questdlg(promptMessage, titleBarCaption, 'OK', 'Quit', 'OK');
if strcmpi(button, 'Quit')
	return;
end

% Play the sound as many times as the user wants.
playAgain = true;
counter = 1;
while playAgain
	% Play the sound that we just created.
	fprintf('Playing file %s   %d times...\n', fullFileName, counter);
	player = audioplayer(y, Fs);
	play(player);
	% Ask user if they want to play the sound again.
	promptMessage = sprintf('You have played the altered sound %d times.\nDo you want to play the altered sound again?', counter);
	button = questdlg(promptMessage, titleBarCaption, 'Yes', 'No', 'Yes');
	if strcmpi(button, 'No')
		playAgain = false;
		break;
	end
	counter = counter + 1;
end

% Alert user that we are done.
message = sprintf('Done playing %s.\n', fullFileName);
fprintf('%s\n', message);
promptMessage = sprintf('Done playing %s.\nClick OK to close the window\nor Cancel to leave it up.', fullFileName);
titleBarCaption = 'Continue?';
button = questdlg(promptMessage, titleBarCaption, 'OK', 'Cancel', 'OK');
if strcmpi(button, 'OK')
	close all;	% Close down the figure.
end

[Jesús Antonio Cubillos Manrique]

Hello, maybe can you give me your email? i have some questions, If you can help me i'll thanks always, thank you! my email is: [e-mail], i hope your request soon

[Walter Roberson]

Image Analyst does not offer email support. If you have questions, then post them.

[Sittisat Chaiyahan]

Sorry I have a question ? , If i need to RGB picture substitute Gray picture from this code. Can i do it please guide me.

[Image Analyst]

If you want, you could convert it to gray scale:

grayImage = imread(fileName);
if ndims(grayImage) >= 3
    grayImage = rgb2gray(grayImage);
end

[Walter Roberson]

If you take an RGB image, and

newImage = reshape(rgbImage, size(rgbImage,1), []);

then newImage is a grayscale image that is three times as wide as the original image.

[Sittisat Chaiyahan]

sorry to ask But I want to know the frequency of the original waveform what is the value And it depends on which variable? Fs, T please and the last question % Make the binary signal for BPSK the same size as the image. phase = imresize(binaryImage(:), [length(y), 1]); % Invert the signal wherever the binary image is 1 y(phase) = -y(phase); * how it work **

[Walter Roberson]

@Sittisat Chaiyahan

Images do not have a frequency.

The audio file is being written according to the value of Fs, which the code arbitrarily assigns as

% Set up the time axis:
Fs = 8000;

You can change the Fs value to change the frequency.

% Make the binary signal for BPSK the same size as the image.

phase = imresize(binaryImage(:), [length(y), 1]);

% Invert the signal wherever the binary image is 1

y(phase) = -y(phase);

At that point, y is the carrier signal, constructed for Fs frequency and duration seconds. length(y) is the number of samples in the carrier frequency. imresize is then told to resize the binary image to have the same number of entries as the carrier signal has entries. This is a "lossy" conversion of the image.

My interpretation of the requirements of the project are quite different than what Image Analyst has implemented, so this is not code that I would write for the purpose.

Answer 2

[Jesús Antonio Cubillos Manrique]

Image Analyst, Good Afternoon

I have to make a project in my university where I have to send an image through Audio port. Thanks for you I can use the Transmisor because it generate the principal signal. Now, I have to try make the Receptor. Maybe can you help me please.

Thanks.

Good Wishes.

[Image Analyst]

I don't have code for that. I'd have to figure it out just like you would.

Answer 3

[Sittisat Chaiyahan]

Hello Image Analyst,

I'm interested in your code but I have a question.

If I want to convert audio files To return to the original image that I put in, can I do it? please guide me

Thank you very much :) :)

[Walter Roberson]

It is something that it is possible to do.

First you write code that takes an array of data samples and converts it back to an image. You test it with an array of data that you converted from image to array but have not yet written to file. Then once you have that working, you put in the step of writing to file and reading it back from file.