How can I change phase image to gray code?

name = ['C:\Users\User\Desktop\trail.jpg'];
im = imread(name); im = im(:,:,2);
im= im2double(im);
imbin = imbinarize(im);
imbin = qammod(imbin,4,'gray');  %this part doesn't work

I tried to use function bin2gray, but it didn't work anymore. Any other alternatives failed me. My only option is doing it mannualy by if but I know this is reallby bad solutions for this problem. (30 000 000 iterations).

This is theoretical scheme how to do it. I have 6 images with fringes.

My error log

Error using qammod
Expected input number 1, X, to be one of these types:

double, single, uint8, uint16, uint32, uint64, int8, int16, int32, int64

Instead its type was logical.

Error in qammod>validateInput (line 262)
            validateattributes(x, {'numeric'}, {'real','integer','>=',0,'<',M}, mfilename, 'X', 1);

Error in qammod (line 94)
    validateInput(x, M, bitInput, outputDataType);

Error in zad2 (line 24)
    imbin = qammod(imbin,4,'gray');
 

[Image Analyst]

Then attach your data and code to read it in with the paperclip icon after you read this:

TUTORIAL: How to ask a question (on Answers) and get a fast answer

[Lukasz Sarnacki]

I have added it. Can you help me now?

[Image Analyst]

No. Maybe someone else can. I don't have the Communications toolbox that qammod is in.

Answer 1

[VINAYAK LUHA]

Hi Lukasz,

As per my understanding, the issue is due to type mismatch between the formal and actual parameters that the “qammod” function takes.

Use the “im2double” function to typecast the matrix “imbin” from logical to double type prior to calling the “qammod” function to resolve the type mismatch error.

Here’s the documentation of “im2double” for your reference.

https://in.mathworks.com/help/matlab/ref/im2double.html

I hope it helps!

Answer 2

[Walter Roberson]

name = 'trial1.jpg';
im = imread(name);
if ndims(im) > 2; im = im(:,:,2); end
im= im2double(im);
imbin = double(imbinarize(im));
imbin = qammod(imbin,4,'gray');

whos

  Name           Size                 Bytes  Class     Attributes

  ans            1x35                    70  char                
  cmdout         1x33                    66  char                
  im          1920x1080            16588800  double              
  imbin       1920x1080            33177600  double    complex   
  name           1x10                    20  char                

imagesc(real(imbin)); title('real'); colorbar

imagesc(imag(imbin)); title('imag'); colorbar

That particular file is an example of a rare grayscale JPEG image, so you have to be careful how you read it.

Note that imbinarize() converts each location to either false (less that the threshold) or true (greater than the threshold), which is an alphabet of size 2. You are asking for qammod to process it as if it were an alphabet of size 4. That will work, but it is a bit inefficient.