# 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...

7 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...

7 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...

8 years ago | 0

Submitted

Affine optic flow

Estimates the parameters of an affine (first-order) optic flow model from two images.

8 years ago | 5 downloads |

Submitted

Hough transform for circles

A Hough transform function for detecting circles, optimised to allow search over radii.

8 years ago | 21 downloads |

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.

8 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.

8 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...

8 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 ...

8 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...

8 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))))

8 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...

8 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...

8 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.

8 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>.

8 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...

8 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...

8 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...

8 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>.

8 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/...

8 years ago | 2

| accepted

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, '...

8 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...

8 years ago | 4

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; ...

8 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. ...

8 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...

8 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...

8 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...

8 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...

8 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...

8 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 ...

8 years ago | 0

| accepted