How can I transmit JPG file within in 8bit array for visible light communication

I tried some progarm. but thre is some issue. How can I fix it? i need to transmit an image.

i=imread('Image.jpg');
R = i(:,:,1); %red 
G = i(:,:,2); %green  
B = i(:,:,3); %blue
for i=1:183
    for j=1:275
        R(i,j);
        bin_Str = dec2bin(R(i,j));
        C = reshape(bin_Str',1,numel(bin_Str));
        D = reshape(C,size(bin_Str,2),size(bin_Str,1));

[Walter Roberson]

What is the point of your C and D? . For example intensity 13, dec2bin would be '1101'. Transpose gives

'1'
'1'
'0'
'1'

reshaping that to 1 row gives '1101' again, exactly what you already had. size('1101',2) is 4, and it has 1 row so D is reshape('1101',4,1) which gives the column vector again. What is the point??

[Thakshila Dayani]

I havent idia about it. but I tried above code. I need to transmit image in led driver. and also the reciving part. how can i do it the best?

Answer 1

[Walter Roberson]

filename = 'flamingos.jpg';
img = imread(filename);
bitstream = reshape((dec2bin(img(:), 8) - '0').', 1, []);

reconstructed = uint8( reshape(bin2dec(reshape(char(bitstream + '0'), 8, []).'), size(img)) );

imshow(img);
title('original');

imshow(reconstructed);
title('reconstructed');

[Thakshila Dayani]

Thank you so much. How Can I save this bit streems in one array?

i=imread('dog.jpg');
R = i(:,:,1); %red 
G = i(:,:,2); %green  
B = i(:,:,3); %blue
for i=1:183
    for j=1:275
        R(i,j);
        bin_Str = dec2bin(R(i,j));
        bitstream = reshape((dec2bin(i(:), 8) - '0').', 1, [])
    end
end

[Walter Roberson]

The code I posted before converts the entire image all at once; there is no need to loop and no need to store anything other than what I already posted.

If you had a particular need to seperate out the red from the green from the blue, then the red part is the first 1/3 of bitstream, the green is the next 1/3, and the blue is the last 1/3 .

If you want to know where the bits for a particular location

i(row, column, pane)

are, they are at bitstream index

(sub2ind(size(i), row, column, pane)-1)*8 + (1:8)

[Thakshila Dayani]

Thank You very much for your support. Then how can I transmit this image using raspberry pi devices with a led driver?

[Walter Roberson]

If you are going to transmit it by raspberry pi, leave it as bytes and send the bytes to the raspberry pi and have the program there do the bit work. Bit extraction is fairly easy in C: >> N bits, & with integer 1, result is a bit, where N is 0 for the least significant bit and N is 7 for the most significant bit.

[Thakshila Dayani]

How to send this Matlab code using Arduino?

[Walter Roberson]

I would make the same recommendation for Arduino as for Raspberry Pi: send the entire bytes over the link, and have the destination break out the bits for transmission purpose. Write a bit of C or C++ code that will execute on the destination.

[Thakshila Dayani]

ok. Thank you.