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how to compute gradients of image using gradient() in matlab2010
As Thorsten says, you should always post the error message. But here's a guess at what might help: im=imread('31.png'); ...

9 years ago | 0

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To run a function
If you call the function without a result variable, MATLAB assigns the result to the variable |ans|. That is min([3 2 1 5 6...

9 years ago | 1

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how can i set the pixel intensity values (I) that fall in the range, 200> I >30 to I = 200.
Img(200 > Img & Img > 30) = 200;

9 years ago | 0

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How do I calculate yearly average value for large data set with uneven time spacing?
If your 2-column matrix is A, try: years = floor(A(:,1)); data = A(:,2); means = accumarray(years, data) ./ accumarra...

9 years ago | 1

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Is there a simple way to reference months from data in matlab time?
Using the attached function, you can do this: [isplit, ~, meantime] = splitTimes(tm, 'month'); % get start and end point of...

9 years ago | 1

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assigning to object variables from within-object functions
MATLAB always makes a copy when you assign an object, or pass an object to a function. Here's another example of the same thing,...

9 years ago | 0

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Why do get error in line 10: Function Keyword is invalid here. This might cause later messages about end.
You can't mix a script and a function in the same m-file. If an m-file contains a function, the first line of code in the file m...

9 years ago | 2

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Answered
how to evaluate a convolution integral by fast fourier transform
Correct zero-padding to use the FFT for 1-D or 2-D convolutions is implemented in my FEX submission <http://uk.mathworks.com/mat...

9 years ago | 0

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Answered
Is there a way to direct an algorithm in edge detection, or correct my drawing outline of the edge?
This is exactly what active contours, or snakes, were originally designed for. If you have the Image Processing Toolbox, have a ...

9 years ago | 0

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Delete a column from an array of uncertain size?
The trick needed is to use the fact that cell arrays can be expanded into comma-separated lists, so can represent any number of ...

9 years ago | 1

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how can i save pixel changes in image?
Could be because JPEG compression loses information, so a write followed by a read only returns an approximation to the original...

9 years ago | 0

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How to arrange stacked Images into a 2 dimension array?
Images2d = reshape( ... permute( ... reshape(Images, 1000, 1000, 8, 5), ... ...

9 years ago | 0

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Can you use MATLAB for 3D Image Processing?
It may be useful to look at the <http://uk.mathworks.com/products/computer-vision/index.html Computer Vision System Toolbox>, wh...

9 years ago | 1

Question

parfor warning and analysis of switch statement
I have two functions which are, I think, functionally identical. Both use a |parfor| loop. If the logic within the loop is expre...

9 years ago | 1 answer | 1

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the rang of unit 8 is 0-255 But im2double convert the range to [0, 1] instead of [0, 255]. please anyone explain it????
It's very helpful to have a standard range of values for images. The convention used in MATLAB toolbox functions is that images ...

9 years ago | 3

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what are the units of the houghlines 'FilleGap' and 'MinLength' ?
Yes, they are in pixels.

10 years ago | 0

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[DEPRECATED] What frustrates you about MATLAB?
The |inputParser / validateattributes / validatestring| collection of function parsing and checking tools. * You have to writ...

10 years ago | 5

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Using knnsearch to find nearest values ignoring NaN's
You need to organise the nearest neighbour search so that it uses both latitude and longitude together, not search each separate...

10 years ago | 0

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Answered
Undefined function 'mtimes' for input arguments of type 'audiorecorder'.
Presumably you replaced data = wavrecord( ... ); by data = audiorecorder( ... ); (I don't know what arguments we...

10 years ago | 0

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Matrix dimension reduction based on summation
If you try to reduce an 81 x 81 matrix to a 10 x 10 matrix it is bound to be messy, because 81 is not a multiple of 10. You have...

10 years ago | 1

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Multiplying structures together based on field names
A function to multiply two structures field by field. This needs to be copied into a file on your MATLAB path called multiplyStr...

10 years ago | 0

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How to change a range of pixel values in a Grayscale JPEG image?
Like this (where A is the array containing the image): A(A >= 60 & A <= 95) = 255; By the way, that the image is stored ...

10 years ago | 0

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Answered
Splitting an array and working on individual sections.
If you want to put the four smaller arrays into separate variables, you can do it like this (assuming the sizes are even as stat...

10 years ago | 0

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Improve efficiency of array multiplication
The value of SW is not used in the code you've shown. If you don't need the value of SW, it will help to omit this line. If you ...

10 years ago | 0

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subtraction ele by ele
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10 years ago | 0

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What is an edge exacty in matlab? is it simply a line ?
I assume you're referring to David Legland's <http://www.mathworks.com/matlabcentral/fileexchange/7844-geom2d toolbox> from the ...

10 years ago | 0

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Answered
How can use a for loop to name a matrix?
One way is to use a cell array, like this for trials = 1:max_trials < compute result, assign to a > output_matri...

10 years ago | 0

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Using fileparts and combining with a different file name
The last line should be filenc = [fName '.nc']; What you are doing here is concatenating two strings. Square brackets ca...

10 years ago | 1

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Answered
What causes an "Argument to dynamic structure reference must evaluate to a valid field name" error please? code attached.
The dot after |sin| makes it look like a structure rather than a function call. Omit the dot.

10 years ago | 1

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Filling in array with specific numbers
One way, using |repmat| to make the repeated values: % test data A = [1;2;3]; B = [11;12;13;14]; C = [21;22;23]; ...

10 years ago | 4