# David Young

### University of Sussex and University of Southampton

Professional Interests: Image Processing

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**Content Feed**

How can I overlap two images/pictures in Matlab?

You can use |hold| to superimpose contour lines on an image. Here's an example: % Get an image from a jpg file img = imr...

6 years ago | 2

Image to Image correlation (moving window) function colfilt

You are likely to find <http://uk.mathworks.com/help/images/ref/normxcorr2.html normxcorr2> more suitable that |colfilt| for thi...

6 years ago | 0

create a sliding window to determine when a % of numbers in a sequence equal a certain value.

The answer to problems involving a sliding window is very often to use the convolution operation, as here. % some random t...

6 years ago | 0

How do I connect plot points with lines using ginput?

The attached function should show you how to do what you need, though you will have to modify it for your purpose.

6 years ago | 1

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Finding columns that contain both integers and NaN

Yes, |isnan(x)| does what |x == NaN| would do if NaNs were equal to each other.

6 years ago | 0

How do I use the ismember function (if possible) to locate the min/max GMT time elements within a cell array?

The problem is that you are passing |ismember| a cell array containing numbers, but it can handle cell arrays only if all they c...

6 years ago | 1

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Creating Gibbs Ringing by changing tissue intensity

I guess you haven't had an answer yet because "Gibbs Ringing" is quite a technical and specialised area. However, the substance ...

6 years ago | 0

Save ginput values under a for loop

Just replace [B,A]=ginput; with [B(index), A(index)] = ginput; to store each pair of inputs in array elements. I...

6 years ago | 0

How can I use plus operation with more than 2 array

Either use A + B + C + D + Z or plus(A, plus(B, plus(C, plus(D, Z))))

6 years ago | 0

ICA image analysis steps

There's an ICA package on the <http://uk.mathworks.com/matlabcentral/fileexchange/38300-pca-and-ica-package file exchange> and a...

6 years ago | 0

What does step instruction in matlab do?

It is documented: see <http://uk.mathworks.com/help/vision/ref/vision.videofilereader.step.html this>. Note that you have to loo...

6 years ago | 0

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Is fftn() and ifftn() equivalent to a 3D Fourier Transform in this case?

|fftn(X)| and |ifftn(X)| carry out a 3-D FFT or a 3-D inverse FFT if |length(size(X))| is equal to 3.

6 years ago | 0

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How to smoothen cropped image?

If you have the Image Processing Toolbox, you could use <http://uk.mathworks.com/help/images/ref/imgaussfilt.html imgaussfilt>.

6 years ago | 0

ellispse detection for cornea edges

General purpose ellipse detection may not be the best solution to this problem - if you haven't already seen it, <http://users.s...

6 years ago | 0

What is the difference in these two methods of finding coordinates of image?

The results of |find| are |[row, column]|. The results of |ginput| are |[column, row]|. That is, |find| uses the matrix conve...

6 years ago | 0

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please give me a detailed description of sift transform in matlab coding and how they works

The <https://en.wikipedia.org/wiki/Scale-invariant_feature_transform Wikipedia article> is a good starting point. It has referen...

6 years ago | 0

NEED A GAUSS FILTER CODING USING IMAGE PROCESSING with some Examples

If you have the Image Processing Toolbox, use <http://uk.mathworks.com/help/images/ref/imgaussfilt.html imgaussfilt>.

6 years ago | 0

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How to deform an image

Yes, it's <http://uk.mathworks.com/help/images/ref/imwarp.html imwarp>. You'll probably also want <http://uk.mathworks.com/help/...

6 years ago | 1

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how to colored the edge detection result(binary image)?

You can set the colour map when you display the binary image. For example img = imread('pout.tif'); imedge = edge(img, '...

6 years ago | 0

command or code for detecting zero crossing points in a signal

You can use logical tests to find the indices between which the signal changes sign. Then you need to interpolate if you want to...

6 years ago | 3

How can I repeat the following text 5000 times and save the solutions for the 5000 different betas in a 1x 5000 matrix ?

betas = zeros(1, 5000); % make array to store results for k = 1:5000 % ... your code ... betas(k) = beta; ...

6 years ago | 0

how to make global variable in matlab so that we can use in any .m file or any other method to use a variable in many .m files

If the m-files are scripts, they share the same top-level workspace and you can access the same variables from both of them. ...

6 years ago | 0

How to calculate phase angle between two sine wave from vectors

If you know the frequency, it is probably more accurate to fit a sine wave to each of the two vectors than to use the FFT. The p...

6 years ago | 0

How do reshape cell array row to new vectors?

First, there's an error to correct. |Big_RIR_AVG(1)| is not a 59x1 double. It's a scalar cell containing a 59x1 double. This mig...

6 years ago | 1

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Enable/Disable uitabs in uitabgroup, with v2015b

A quick thought - how about using the SelectionChangedFcn callback of the uitabgroup object, to select another tab when one of t...

6 years ago | 0

Shortest path that passes through certain nodes

If you search online for "travelling salesman problem matlab" you will find discussion and code that will help with this problem...

6 years ago | 0

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How can I add a digit to a pre-existing number randomly ?

To take a random sample from a vector, just use *randi* - no need for *randsample*. Example: numbers = [2, 3, 9, 7]; ran...

6 years ago | 1

Help using accumarray on a 3d-matrix

I think it's simpler to use *mean* directly and avoid *accumarray*. So to get all the rainfall for 1999, for example, you could ...

6 years ago | 0

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How to find the "true" perimeter of objects in a binary image?

One possible way is like this: % Example binary image with 3 non-zero pixels img = false(5); % Use zeros(5) if you pref...

6 years ago | 0

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Please help me to convert opencv matrix multiplication into matlab

Your code is fine, it's just rounding error. Note that the differences are smaller, by many orders of magnitude, than the larges...

6 years ago | 0

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