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Puzzler: Quickly tell if two absolute indices (a,b) are four connected for n x m matrix.
function flag = isFourConnected(a,b,n,m) % % a,b: indices of interest a ~= b % n,m: size of matrix of interest % ...

14年以上前 | 4

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difference between "imread" and "load" an image
Images can be saved as files on disk in a variety of formats. The formats are often known by their filename extensions, such as ...

14年以上前 | 1

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Calculate the average % two stocks are correlated
corrcoeff, perhaps, if you don't want to introduce the possibility of time lags between the stock price sequences.

14年以上前 | 0

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put together data of type char
You can use square brackets to concatenate any matrices. For example [A B] puts B to the right of A, whilst [A; B] ...

14年以上前 | 0

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fractional fourier transform
Use fft2 on each of the colour planes in turn, for example Ft_image(:,:,1) = fft2(Image(:,:,1)); Ft_image(:,:,2) = fft2(Ima...

14年以上前 | 0

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directions from cartesian xy coordinate pairs
Have a look at the atan2 function. I suspect that xc and yc and the factor of 26 are irrelevant, and you just need something lik...

14年以上前 | 0

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std2 ROI
std(Image(logical(binary_mask)))

14年以上前 | 0

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Need to compare images with different pixel counts
If you have the Image Processing Toolbox, use *imresize*.

14年以上前 | 0

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How is integral image used in image processing?
Here's a simplified example, that relates to the (more complex) ways that SURF uses integral images. Suppose you want to estima...

14年以上前 | 1

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measure the illumination
No, the camera would need to be calibrated if you want absolute values of the illumination. Even relative values depend on the c...

14年以上前 | 0

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problem with if statment
It's because the result from dec2bin is a character string. So each element of the array x represents a character, '0' or '1', f...

14年以上前 | 0

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expression substitution
s = 'A=g*ABC+(1-g)*(CAD+d*EEA)+ZI/A'; regexprep(s, '(^|\W)A($|\W)', '$1A_subs$2') *EDIT*: See Walter Roberson's comment for...

14年以上前 | 1

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What is your time zone?
GMT+01 (now, summer) GMT+00 (winter)

14年以上前 | 0

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Way to tell % complete of script
If the script is already running, no. If * the script has not yet started running * you can identify the main loop * eac...

14年以上前 | 0

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move rectangle over te image
If you have an array A, and you want the sum of the values in a rectangle whose top and bottom are rows R1 and R2, and whose lef...

14年以上前 | 0

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Signal Processing / Model Evidence !!
In general, you need to make some assumptions about what might have happened to the signals (e.g. addition of noise, non-linear ...

14年以上前 | 2

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SURF matching
The Euclidean distance between vectors A and B is computed simply using norm(A-B) This applies to SURF descriptor vector...

14年以上前 | 0

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convfft vs. fftfilt (1D convolution)
The relative speed depends on the the sizes of the vectors. The best way to find out which is fastest is to experiment - and tha...

14年以上前 | 0

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Speeded up robust feature(SURF) ?
Not really a MATLAB question - but anyway, the scale at which the feature was detected is used to determine its dominant orienta...

15年弱前 | 0

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Padding FFT causes inconsistent arrays when data transferred back to time domain
You could try this: raw = rand(1, 100); FREQDATA = fft(raw, 2^nextpow2(10*length(raw))); % Process FREQDATA here n...

15年弱前 | 0

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Circle reconstruction algorithm
Have a look at the circle-finding <http://www.mathworks.com/products/image/demos.html?file=/products/demos/shipping/images/ipexr...

15年弱前 | 0

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How do I smooth 2D vector field data?
Split your vector field into components (how to do this depends on how it is stored to start with). Smooth each component separa...

15年弱前 | 2

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How to measure % intensity difference between 2 image?
imDiff = image1 - image2; imSum = image1 + image2; percentDiff = 200 * mean(imDiff(:)) / mean(imSum(:)); imAdjust...

15年弱前 | 0

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artifacts of Horn-Schunck velocities
Perhaps by using a method such as feature matching that does not involve smoothing? There are a number of offerings on the file ...

15年弱前 | 0

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Basic probability question
You can make a function that you can use instead of rand, like this: p1 = 0.6; % probability of a 1 in the output ran...

15年弱前 | 0

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Need help with implementing a 2D elliptical Gaussian function
You can make an elliptical filter aligned with the axes by replacing the second occurrence of c1 by a different variable, say c2...

15年弱前 | 1

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Independence Day weekend puzzler
I'm sorry about this one - it's somewhat over the top, and I promise I won't do any more. However, since I think it's a differen...

15年弱前 | 0

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Independence Day weekend puzzler
Also one line of code (formatting for the web page will display it over more than one line of text): double(regexprep(char(...

15年弱前 | 0

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Independence Day weekend puzzler
One-liner, avoiding string operations: diff([0 (floor((sum(x.*10.^(length(x)-1:-1:0))+1) ./ 10.^(floor(log10(sum(x.*10.^(leng...

15年弱前 | 1

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Detecting a string and getting the entire sentence
It is difficult to make a robust and general solution, because you have to define very carefully what makes the start and end of...

15年弱前 | 2