How to convert a uint8 image to complex double?

I want to convert a png file into a complex valued number. The current dimension and format of the png file is:

320x320x3 uint8

I want to convert into the format like the format below:

320x320 complex double

When I use the

A = imread("01.png");
Img = im2double(A);

The output comes as:

320x320x3 double

But I want the third dimension to be removed and merge into 320x320.

[Walter Roberson]

How should the real part be calculated? How should the imaginary part be calculated?

[Gulfam Saju]

It can be calculated using the two matlab functions:

real(Img);
imag(Img);

[Walter Roberson]

An array that shows up as 320x320x3 uint8 is not complex-valued

A = randi([1 255], [5 5 3], 'uint8');
Ar = real(A);
Ai = imag(A);
nnz(Ar), nnz(Ai)

ans = 75

ans = 0

Ari = complex(Ar, Ai);

whos A Ar Ai Ari

  Name      Size             Bytes  Class    Attributes

  A         5x5x3               75  uint8              
  Ai        5x5x3               75  uint8              
  Ar        5x5x3               75  uint8              
  Ari       5x5x3              150  uint8    complex   

Notice that A, the original image, does not show up as complex, and the the number of non-zero complex parts of it was zero. You can deliberately put a complex layer onto it, but as soon as any math is done on it, it will strip off the all-zero complex layer

Ard = im2double(Ar);
Aid = im2double(Ai);
Arid = complex(Ard, Aid);
Arid_plus = Arid + 0;
whos Ard Aid Arid Arid_plus

  Name           Size             Bytes  Class     Attributes

  Aid            5x5x3              600  double              
  Ard            5x5x3              600  double              
  Arid           5x5x3             1200  double    complex   
  Arid_plus      5x5x3              600  double              

Answer 1

[Sulaymon Eshkabilov]

One of the dimensions can be removed using squeeze() fcn or taking averaged pixel values from R, G, B layers:

D = imread('01.png');
Dd = im2double(D);
Ds = squeeze(Dd(:,:,1));   % Red layer is considered
DD = mean(Dd, 3);          % Averaged pixel values computed from Red, Green, Blue 

[Gulfam Saju]

Thank you, it worked.

[Sulaymon Eshkabilov]

Most welcome!

[Walter Roberson]

The squeeze() is not doing anything useful there in creating Ds. Also, Ds is not used afterwards.

This code creates DD as the mean of R, G, and B (which, by the way, is not what you would do to convert to grayscale), but DD will not be complex.