How can I change phase image to gray code?

Question

Lukasz Sarnacki 2022-8-22

0
链接

此问题的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1783305-how-can-i-change-phase-image-to-gray-code

编辑： Walter Roberson 2023-8-31

trial1.jpg

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');
 

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Lukasz Sarnacki 2022-8-23

I have added it. Can you help me now?

Image Analyst 2022-8-24

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

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Answer 1

VINAYAK LUHA 2023-8-31

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此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1783305-how-can-i-change-phase-image-to-gray-code#answer_1297901

编辑：Walter Roberson 2023-8-31

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!

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Answer 2

Walter Roberson 2023-8-31

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链接

此回答的直接链接

https://ww2.mathworks.cn/matlabcentral/answers/1783305-how-can-i-change-phase-image-to-gray-code#answer_1297931

编辑：Walter Roberson 2023-8-31

在 MATLAB Online 中打开

trial1.jpg

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.