How can I change phase image to gray code?

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Lukasz Sarnacki
Lukasz Sarnacki il 22 Ago 2022
Modificato: Walter Roberson il 31 Ago 2023 alle 6:21
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');
  3 Commenti
Image Analyst
Image Analyst il 24 Ago 2022
No. Maybe someone else can. I don't have the Communications toolbox that qammod is in.

Accedi per commentare.

Risposte (2)

VINAYAK LUHA il 31 Ago 2023 alle 5:54
Modificato: Walter Roberson il 31 Ago 2023 alle 5:57
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.
I hope it helps!

Walter Roberson
Walter Roberson il 31 Ago 2023 alle 6:05
Modificato: Walter Roberson il 31 Ago 2023 alle 6:21
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');
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.


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