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  • why arrayfun does NOT improve my struct array operation performance

    - by HaveF
    here is the input data: % @param Landmarks: % Landmarks should be 1*m struct. % m is the number of training set. % Landmark(i).data is a n*2 matrix old function: function Landmarks=CenterOfGravity(Landmarks) % align center of gravity for i=1 : length(Landmarks) Landmarks(i).data=Landmarks(i).data - ones(size(Landmarks(i).data,1),1)... *mean(Landmarks(i).data); end end new function which use arrayfun: function [Landmarks] = center_to_gravity(Landmarks) Landmarks = arrayfun(@(struct_data)... struct('data', struct_data.data - repmat(mean(struct_data.data), [size(struct_data.data, 1), 1]))... ,Landmarks); end %function center_to_gravity when using profiler, I find the usage of time is NOT what I expected: Function Total Time Self Time* CenterOfGravity 0.011s 0.004 s center_to_gravity 0.029s 0.001 s Can someone tell me why? BTW...I can't add "arrayfun" as a new tag for my reputation.

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  • calling function in radiobutton group

    - by vijisai
    thank you very much. with your help, i am now able to call the function for each radio button. however, i get a error message Reference to non-existent field 'ics_si' ics_si is my function, which has the following code, i do not know where i am making a mistake i have created the edit box for user to input the values for bore and stroke. and vdisp is calculated and the result is displayed in the third edit box. function ics_si_Callback(hObject, eventdata, handles) b = str2double(get(handles.bore,'String')); s = str2double(get(handles.stroke,'String')); vdisp = (pi * b * b * s*10^(-3))/4; set(handles.vdisp,'String',vdisp); this code must be called when i press the first or second radio button. i.e. when the radio button is pressed, it should call the function ics_si, calculate it and display the result. how to get this.

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  • ??? Error using ==> dlmread at 55 Filename must be a string.

    - by Tim
    [file_input, pathname] = uigetfile( ... {'*.txt', 'Text (*.txt)'; ... '*.xls', 'Excel (*.xls)'; ... '*.*', 'All Files (*.*)'}, ... 'Select files'); D = uiimport(file_input); M = dlmread(D); X = freed(M); Getting errors with dlmread......"??? Error using == dlmread at 55 Filename must be a string."..need to get the data from dlmread to "freed"

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  • How to unblend two images from a blend image

    - by gavishna
    I have blended/merged 2 images img1 and img2 with this code which is woking fine.What i want to know is how to obtain the original two images img1 and img2.The code for blending is as under img1=imread('C:\MATLAB7\Picture5.jpg'); img2=imread('C:\MATLAB7\Picture6.jpg'); for i=1:size(img1,1) for j=1:size(img1,2) for k=1:size(img1,3) output(i,j,k)=(img1(i,j,k)+img2(i,j,k))/2; end end end imshow(output,[0 255]);

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  • Triangulation & Direct linear transform

    - by srand
    Following Hartley/Zisserman's Multiview Geometery, Algorithm 12: The optimal triangulation method (p318), I got the corresponding image points xhat1 and xhat2 (step 10). In step 11, one needs to compute the 3D point Xhat. One such method is Direct Linear Transform (DLT), mentioned in 12.2 (p312) and 4.1 (p88). The homogenous method (DLT), p312-313, states that it finds a solution as the unit singular vector corresponding to the smallest singular value of A, thus, A = [xhat1(1) * P1(3,:)' - P1(1,:)' ; xhat1(2) * P1(3,:)' - P1(2,:)' ; xhat2(1) * P2(3,:)' - P2(1,:)' ; xhat2(2) * P2(3,:)' - P2(2,:)' ]; [Ua Ea Va] = svd(A); Xhat = Va(:,end); plot3(Xhat(1),Xhat(2),Xhat(3), 'r.'); However, A is a 16x1 matrix, resulting in a Va that is 1x1. What am I doing wrong (and a fix) in getting the 3D point? For what its worth sample data: xhat1 = 1.0e+009 * 4.9973 -0.2024 0.0027 xhat2 = 1.0e+011 * 2.0729 2.6624 0.0098 P1 = 699.6674 0 392.1170 0 0 701.6136 304.0275 0 0 0 1.0000 0 P2 = 1.0e+003 * -0.7845 0.0508 -0.1592 1.8619 -0.1379 0.7338 0.1649 0.6825 -0.0006 0.0001 0.0008 0.0010 A = <- my computation 1.0e+011 * -0.0000 0 0.0500 0 0 -0.0000 -0.0020 0 -1.3369 0.2563 1.5634 2.0729 -1.7170 0.3292 2.0079 2.6624

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  • measuring uncertainty in matlabs svmclassify

    - by Mark
    I'm doing contextual object recognition and I need a prior for my observations. e.g. this space was labeled "dog", what's the probability that it was labeled correctly? Do you know if matlabs svmclassify has an argument to return this level of certainty with it's classification? If not, matlabs svm has the following structures in it: SVM = SupportVectors: [11x124 single] Alpha: [11x1 double] Bias: 0.0915 KernelFunction: @linear_kernel KernelFunctionArgs: {} GroupNames: {11x1 cell} SupportVectorIndices: [11x1 double] ScaleData: [1x1 struct] FigureHandles: [] Can you think of any ways to compute a good measure of uncertainty from these? (Which support vector to use?) Papers/articles explaining uncertainty in SVMs welcome. More in depth explanations of matlabs SVM are also welcome. If you can't do it this way, can you think of any other libraries with SVMs that have this measure of uncertainty?

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  • How to speed this kind of for-loop?

    - by wok
    I would like to compute the maximum of translated images along the direction of a given axis. I know about ordfilt2, however I would like to avoid using the Image Processing Toolbox. So here is the code I have so far: imInput = imread('tire.tif'); n = 10; imMax = imInput(:, n:end); for i = 1:(n-1) imMax = max(imMax, imInput(:, i:end-(n-i))); end Is it possible to avoid using a for-loop in order to speed the computation up, and, if so, how?

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  • Problem with xor operation

    - by gavishna
    Kindly tell me why the original image is not coming with this code. The resulting image receive is yellowish in color,instead of being similar to the image Img_new Img=imread(‘lena_color.tif’); Img_new=rgb2gray(img); Send=zeroes(size(Img_new); Receive= zeroes(size(Img_new); Mask= rand(size(Img_new); for i=1 :256 for j=1:256 Send(i,j)=xor( Img_new(i,j),mask(i,j)); End End image(send); imshow(send); for i=1 :256 for j=1:256 receive(i,j)=xor( send(i,j),mask(i,j)); End End image(receive); imshow(receive); plz help

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  • How to convert a one column integer data file into a mask for image

    - by gavishna
    I have a data file which contains integers say in range 0-255 containing about 1000 integers which are random in nature.I want to use that as a mask or to multiply an image which is in RGb and another image which is in gray format. HOw do i go about this, how do i convert/represent this data file in matrix format of image dimension ?Kindly suggest. also is it possible to obtain a 3D histogram?

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  • Better way to compare neighboring cells in matrix

    - by HyperCube
    Suppose I have a matrix of size 100x100 and I would like to compare each pixel to its direct neighbor (left, upper, right, lower) and then do some operations on the current matrix or a new one of the same size. A sample code in Python/Numpy could look like the following: (the comparison 0.5 has no meaning, I just want to give a working example for some operation while comparing the neighbors) import numpy as np my_matrix = np.random.rand(100,100) new_matrix = np.array((100,100)) my_range = np.arange(1,99) for i in my_range: for j in my_range: if my_matrix[i,j+1] > 0.5: new_matrix[i,j+1] = 1 if my_matrix[i,j-1] > 0.5: new_matrix[i,j-1] = 1 if my_matrix[i+1,j] > 0.5: new_matrix[i+1,j] = 1 if my_matrix[i-1,j] > 0.5: new_matrix[i-1,j] = 1 if my_matrix[i+1,j+1] > 0.5: new_matrix[i+1,j+1] = 1 if my_matrix[i+1,j-1] > 0.5: new_matrix[i+1,j-1] = 1 if my_matrix[i-1,j+1] > 0.5: new_matrix[i-1,j+1] = 1 This can get really nasty if I want to step into one neighboring cell and start from it to do a similar task... Do you have some suggestions how this can be done in a more efficient manner? Is this even possible?

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  • How to calculate the current index?

    - by niko
    Hi, I have written an algorithm which iteratively solves the problem. The first iteration consists of 6 steps and all the following iterations consist of 5 steps (first step is skipped). What I want to calculate is the current (local) step in the iteration from current global step. For example if there are 41 steps in total which means there are 8 iterations: indices from 1 to 6 belong to 1st iteration indices from 7 to 11 belong to second iteration ... For calculating the current iteration I have written the following code: if(currentStep <= 6) iteration = 1; else iteration = floor((currentStep - 7)/5) + 2; end The problem remains in calculating local steps. in first iteration the performed steps are: 1, 2, 3, 4, 5, 6 in all the following iterations the performing steps are 2, 3, 4, 5, 6 So what has to be done is to transform the array of global steps [1 2 3 4 5 6 7 8 9 10 11 12 13 ... 41] into array of local steps [1 2 3 4 5 6 2 3 4 5 6 2 3 ... 6]. I would appreciate if anyone could help in finding the solution to a given problem. Thank you!

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  • divide the image into 3*3 blocks

    - by Jayanth Silesh
    I have a matrix that does not happen to have dimensions that are multiples of 3 or it might. How can we divide the entire image into blocks of 3*3 matrices. (Can ignore the last ones which does not come under the 3*3 multiples. Also, the 3*3 matrices can be be saved in arrays. a=3; b=3; %window size x=size(f,1)/a; y=size(f,2)/b; %f is the original image m=a*ones(1,x); n=b*ones(1,y); I=mat2cell(f,m,n);

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  • Filtering spectrum using FIR filters

    - by Alex Hoppus
    If i have signal values x[T] and filter coefficients b[i], i can perform filtering using convolution. Suppose i have spectrum of x (after FFT) and i need to perform filtering using filters coefficients, how can i perform this? I heard that in frequency domain it will be multiplying, rather than convolution (time domain). But i can't find an equation to use it. I have 614000 values in y = fft(x[T]) vector and 119 filter coefficients (generated using fdatool), i can't multiply them directly ... Thanks.

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  • RBF neural networks

    - by Infinity
    Hello guys! I would like to apply RBF neural networks to teach my system. I have a system with an input: | 1 2 3 4 5 6 ... 32 | 33 | | 1000 0001 0010 0100 1000 1000 ... 0100 | 0 0 1 | You have to read this without the "|" character. I just wanted you to see that the last three elements in the input are staying together. The result have to be a number between 1-32, which has the value "1000" in the input. In my training set I will always have a result for an array of this kind. What kind of functions can I use for the teaching algorithm? Can you point me please to the right way? If you can't understand my description please don't hesitate to ask about it. Thank you guys for your help!

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  • image processing project.......................

    - by user358886
    i have got a project to differentiate between fake currency and real currency using image processing but i am having no notion about my project neither i am getting any type of support from my mentor.and i am really frusted about my project.if any one know any thing then let me know...

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  • A question about matrix manipulation

    - by appi
    Given a 1*N matrix or an array, how do I find the first 4 elements which have the same value and then store the index for those elements? PS: I'm just curious. What if we want to find the first 4 elements whose value differences are within a certain range, say below 2? For example, M=[10,15,14.5,9,15.1,8.5,15.5,9.5], the elements I'm looking for will be 15,14.5,15.1,15.5 and the indices will be 2,3,5,7.

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  • second y-axis on pcolor plot

    - by user1155751
    Is it possible to prodce a pcolor plot with 2 yaxis? Consider the following example: clear all temp = 1 + (20-1).*rand(365,12); depth = 1:12; time =1:365; data2 = 1 + (60-1).*rand(12,1); time2 = [28,56,84,124,150,184,210,234,265,288,312,342]; figure; pcolor(time,depth,temp');axis ij; shading interp hold on plot(time2,data2,'w','linewidth',3); Instead of plotting the second dataset on the same y axis I would like it to placed on its own y-axis. Is this possible?

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  • How can I use from ismember

    - by ahmad hosseini
    Assuming A=[32512199.30 5401000.29 347.33 32512199.69 5401000.45 347.39 32512199.67 5401001.32 353.58 32512199.96 5401001.50 346.99 32512196.71 5401001.69 346.62 ] and B=[32512199.30 5401000.29 347.33 32512199.69 5401000.45 347.39 32512199.67 5401001.32 347.00 32512198.85 5401000.91 347.25 32512196.71 5401001.69 346.87 ] I want using ismember extract the rows that have same X and Y and different Z. X is first column, Y is the second and Z is third. in A and B I want extract from A 32512199.67 5401001.32 353.58 and 32512196.71 5401001.69 346.62 OR from B 32512199.67 5401001.32 347.00 and 32512196.71 5401001.69 346.87 How can I do it?

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  • How to compute power spectrum from 2D FFT

    - by user1452954
    I've encounter a problem when doing my lab assignment, not sure how to implement this: Use fft2 on a gray image and to do Fourier transform and then compute the power spectrum. This is my code so far: >> Pc = imread('pckint.jpg'); >> whos Pc; Name Size Bytes Class Attributes Pc 256x256 65536 uint8 >> imshow(Pc); >> result = fft2(Pc); My question is from the result. How to computer power spectrum?

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