Trouble with Stockwell function - basics.

Hi Folks,

I'm a novice and trying to run the dost2_tutorial.m script. when a simply copy and paste the script into matlab, I get an error called: Error in StockWellTutorial (line 76)

dost2_test_signal = dost2(test_signal). I have made this in bold font below - this is my line 76

Line 76 is referenced as I have other code in the script file but it is all % out so is not active.

Can anyone help me identify why I get this error. I have copied the tutorial code directly from the MatLab web site below. It can also be found at: https://www.mathworks.com/matlabcentral/fileexchange/47223-2-dimensional-dost-zip?focused=3830320&tab=function

Much appreciated if anyone can offer some guidance.

Ricky

%

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

% dost2_tutorial (script)

%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

%

% this script shows how to apply the dost2 and the idost2 to images.

% For more informations on the dost2 and the idost2 see the comments

% on their code.

%

% Code by: U. Battisti and L. Riba

% July, 02 2014

%

% References:

% [1] R.G. Stockwell, "Why use the S-Transform", Pseudo-differential

% operators partial differential equations and time-frequency

% analysis, vol. 52 Fields Inst. Commun., pages 279--309,

% Amer. Math. Soc., Providence, RI 2007;

% [2] R.G. Stockwell, "A basis for efficient representation of the

% S-transform", Digital Signal Processing, 17: 371--393, 2007;

% [3] Y. Wang and J. Orchard, "Fast-discrete orthonormal

% Stockwell transform", SISC: 31:4000--4012, 2009;

% [4] Y. Wang, "Efficient Stockwell transform with applications to

% image processing", PhD thesis, University of Waterloo,

% Ontario Canada, 2011;

% [5] U. Battisti, L.Riba, "Window-dependent bases for efficient

% representation of the Stockwell transform", 2014

% http://arxiv.org/abs/1406.0513.

%

%

% Additional details:

% Copyright (c) by U. Battisti and L. Riba

% $Revision: 1.0 $

% $Date: 2014/07/02 $

%

%

% Summary:

% 1) read an image (we use the classical "Lena");

% 2) compute the dost coefficients of the signal;

% 3) compute the inverse dost of the dost to reconstruct the signal;

% 4) plot the signal, the dost coefficients and the reconstructed signal.

clear all

close all

% read the test-signal

test_signal = double(imread('lena.bmp'));

% compute the dost coefficients of the signal "test_signal"

dost2_test_signal = dost2(test_signal);

% reconstruct the signal using the idost2

reconstructed_test_signal = idost2(dost2_test_signal);

figure

subplot(1,3,1)

imagesc(test_signal)

title('test signal')

axis equal

axis tight

subplot(1,3,2)

%imagesc(log(abs(dost2_test_signal)))

imagesc([-.5 .5], [-.5 .5], log(abs(dost2_test_signal)))

title('(log of the norm of the) dost2 of the test signal')

axis equal

axis tight

subplot(1,3,3)

imagesc(real(reconstructed_test_signal))

title('reconstructed test signal')

axis equal

axis tight

colormap gray

[Riccardo Chianese]

Thank you, it is now working.

I would like to create a function to apply Stockwell2D to RGB images and call this function from the batch processing app. Do you have any examples of how to creat such a function?

Many thanks

Ricky

Answer 1

[Samatha Aleti]

Hi,

I understand that you are trying to run the script by copy pasting only the “dost2_tutorial” file. This file is a tutorial and uses “dost2” and “idost2” functions. To run the “dost2_tutorial” file, you need to have “dost2” and “idost2” functions as well.

So, I suggest you to download the MATLAB File Exchange submission “2-Dimensional DOST” which includes all the necessary files for the tutorial and avoids such issues.

Hope this helps!