Adding 0s and 1s to Bit Data

I am using imgread to read binary 0,1 data and have to ultimately send it from an FPGA to a monitor using VGA Interface.The entire process would be greatly facilitated if I could add zeros to a 480x640 matrix(had to transpose original 640x480 because fprintf prints column wise ?).I want to know how to write 0 as 000 or 1 as 111 (corresponding to black and white RGB values)?

fid = fopen('3bitbinary.txt','w');
fprintf("","","");
fclose(fid);

Thanks!

Answer 1

[Chaya N]

From what I understand, it sounds like you need to generate a m x n x 3 matrix and the easiest way might be to simply do a repmat of your matrix. It should look something like this:

output_matrix = repmat(input_matrix,1,1,3);

When writing to file, the values have to be written depth-wise so use:

fprintf('%d %d %d\n', permute(output_matrix,[3 2 1]))

I hope this helps!

[Matlab Student]

Your code will work perfectly well for RGB images, but I have simple zeros and ones and intend to initially keep them as such.

Example

0 0 1 1 1 0

1 1 0 1 0 0

0 1 0 0 1 1

1 0 0 0 0 1

0 0 0 1 1 1

I just want to save them as :

000

000

111

111

111

...

[Chaya N]

The idea is still the same. Since you need each binary 0 or 1 to be represented by 3 bits (in RGB style not regular binary), you would create an m x n x 3 matrix and write it to a file.

The code above will write your example into a file as:

0 0 0

0 0 0

1 1 1

1 1 1

1 1 1

...

I suppose that the confusion here is in the spaces between the bits in each row that is written into the file. To simply remove these spaces, you would skip the spaces between the format specifiers in the fprintf command. You could even skip creating an extra variable output_matrix and do it inline as:

 fprintf('%d%d%d\n', permute(repmat(input_matrix,1,1,3),[3 2 1]))

This rigmarole would be greatly simplified if your read-in values from the FPGA are in vector form. Then again, MATLAB reads and writes data column-wise so you would have to watch out for the direction of your vector (row or column). The above code should be able to handle vectors as well as matrices as input and write it in the format you require.

[Chaya N]

Alternately, you could try the following:

 fprintf('%d%d%d\n', permute(kron(input_matrix,[1 1 1]),[2 1]))

This works too.

[Matlab Student]

Wonderful! Thank you!

Answer 2

[Image Analyst]

Not sure what you're asking, but perhaps you're looking for padarray(). This function will add zeros to a layer around the outside edges of the image, whichever of the 4 sides you specify.