Matlab gradient equivalent in opencv 
You have to call Sobel 2 times, with arguments:
xorder = 1, yorder = 0
and
xorder = 0, yorder = 1
You have to select the appropriate kernel size.
See documentation
It might still be that the MatLab implementation was different, ideally you
should retrieve which kernel was used there...
Edit:
If you need to specify your own kernel, you can use the more generic
filter2D. Your destination depth will be CV_16S (16bit signed).

rgb2lab discrepancy opencv and matlab 
Please refer to function rgb2lab(int R, int G, int B, int []lab) in this
page. The idea is first convert to XYZ and then to lab. It also contains
conversions between other color spaces.

Matlab imagesc clims to OpenCV 
I found the solution. Before doing the normalization I just found all the
matrix elements larger than m+s*3 and changed them to m+s*3, and all the
elements smaller than m+s*3 and changed them to m+s*3. After doing this
with the matrix elements I did the normalization to range from 0 to 1. Same
result like in MATLAB's imagesc with clims.

Different Pixel Values in MATLAB and C++ with OpenCV 
You are converting the image if certain conditions are met, this can change
some color values while MATLAB can choose to not convert the image but use
the raw image
colors are mostly represented in hex format with popular implementations in
the format of 0xAARRGGBB or 0xRRGGBBAA, so 32 bit integers will do
(unsigned/signed doesn't matter, the hex value is still the same), create a
64 bit variable, add all the 32 bit variables together and then divide by
the amount of pixels, this will get you a quite accurate result (for images
up to 16384 by 16384 pixels (where a 32 bit value is representing the color
of one pixel), if larger, then a 64 bit integer will not be enough).
long long total = 0;
long long divisor = image.width * image.height;
for(int x = 0; x < image.width; ++x)
{
for(

Disk Structuring Element opencv vs Matlab 
According to the docs, you could try:
cv::Mat sel = cv::getStructuringElement(MORPH_ELLIPSE, cv::Size(9,9));
This gave me the following structuring element:
0 0 0 0 1 0 0 0 0
0 1 1 1 1 1 1 1 0
0 1 1 1 1 1 1 1 0
1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1
1 1 1 1 1 1 1 1 1
0 1 1 1 1 1 1 1 0
0 1 1 1 1 1 1 1 0
0 0 0 0 1 0 0 0 0
While in MATLAB I got:
>> getnhood(strel('disk',5))
ans =
0 0 1 1 1 1 1 0 0
0 1 1 1 1 1 1 1 0
1 1 1 1 1 1 1 1 1
1 1 1 1

Different SURF Features Extracted Between MATLAB and OpenCV? 
Under the hood, MATLAB uses OpenCV for some of its computer vision
functions, including detecting SURF features. If you look inside the
$matlabroot/bin/$arch folder, you'll find OpenCV shared libraries in
addition to a gateway library ocv.dll).
In fact, the same reference paper is mentioned in the documentation of
both, which suggests that the algorithm parameters have the same meaning in
both frameworks.
MATLAB
Herbert Bay, Andreas Ess, Tinne Tuytelaars, Luc Van Gool "SURF:
Speeded Up Robust Features", Computer Vision and Image Understanding
(CVIU), Vol. 110, No. 3, pp. 346359, 2008
OpenCV
Bay, H. and Tuytelaars, T. and Van Gool, L. "SURF: Speeded Up Robust
Features", 9th > European Conference on Computer Vision, 2006
First thing, make sure you are using the same pa

matlab find function implementation in opencv? 
Assuming Color is a properly initialized singlechannel cv::Mat, you can
use the combination of overloaded operator== and cv::countNonZero() to do
what you wish. operator== returns a mask where each element is one if the
value in Color matches j, or zero otherwise.
if(cv::countNonZero(Color == j))
{
// Do something...
}

Sobel filter output from opencv and Matlab different 
This code gives me the same result as MATLAB code:
int main(int argc, char* argv[])
{
namedWindow("result");
Mat img=imread("D:\ImagesForTest\1.tiff",0);
img.convertTo(img,CV_32FC1,1.0/255.0);
Mat h,v,g;
cv::Sobel(img,h,1,1,0,3,1.0/8.0);
cv::Sobel(img,v,1,0,1,3,1.0/8.0);
cv::magnitude(h,v,g);
// Check extremums
double m,M;
cv::minMaxLoc(g,&m,&M);
cout << m << ":" << M << endl;
cv::minMaxLoc(h,&m,&M);
cout << m << ":" << M << endl;
cv::minMaxLoc(v,&m,&M);
cout << m << ":" << M << endl;
imshow("result",g);
cv::waitKey(0);
}
OpenCV never scales convolution result, so, be careful.

MATLAB + Mex + OpenCV: Links and compiles correctly but can't find library at run time 
I encountered a similar problem some days ago. This problem only happens
when you using the matlab remotely on a cluster. Editing the
LD_LIBRARY_FILE in Matlab is useless, and I don't know why. I solved the
problem by defining the LD_LIBRARY_PATH in .bashrc (or .bash_profile).

Is conversion from OpenCV code to FPGA code is easier than Matlab code or not? 
Firstly  why do you want to use an FPGA? Unless you have to for good
reasons, avoid it!
Good reasons can be things like:
cost
power
size
preexisting hardware which must be reused
personal interest
it's an assignment where FPGAs are mandated
Bad reasons include "imageprocessing... that must mean I need an FPGA!"
Think FPGA
If you want to implement on FPGA you need to think "FPGA" right from the
beginning. They have very particular characteristics compared to
conventional processors, which means that many "conventional" algorithms
are very difficult to implement efficiently on FPGAs. And other algorithms
which conventional processing will struggle with can actually be done quite
simply on an FPGA.
One classic (nonimage) example is CRC calculation, which is often
implemented

OpenCV Error: Assertion failed (ptnum > 3) in unknown function, file (Java + opencv 2.4.6) 
I think the problem lies in the number of points in your convex hull. It
should have at least 3 points to make using the convexityDefect() possible.
It can easily be checked using an if in the for loop:
if(hull_.rows() >= 3){
Imgproc.convexityDefects(contours.get(0), hull_, convexityDefects);
}

opencv libraries precompiled for javacv opencv android project 
It will take a little more effort to "run this code" correctly. In short,
JavaCV is a wrapper on top of OpenCV, and you have to compile the OpenCV
and correctly move all the shared libraries (.so) to your Android
development project etc. Like the original article suggested, you need to
go to JavaCV homepage and read the installation instructions.

How do I find out in the OpenCV C Inerface,...In what .so a OpenCV function is defined 
You need to look into http://docs.opencv.org.
If you were to try and locate the Sobel function for instance, you would
see that the documentation path is (at the top of the webpage OpenCV
2.4.6.0 documentation » OpenCV API Reference » imgproc. Image Processing)
So the corresponding module is imgproc.
You can use this to locate into which module your functions are

OpenCV+Eclipse+Android: Error org.opencv.video Video.java 
If someone have this problem, do this:
In OpenCV project.properties change target=android11 (or in some cases
14) to target=android17.
Edit: For the newer OpenCV2.4.10androidsdk you will need to change it to
target=android20.

Will Matlab standalone be faster than Matlab from UI for long execution code? 
Applications built with MATLAB Compiler should execute at pretty much
exactly the same speed as within MATLAB.
MATLAB Compiler does not convert your MATLAB code into machine code in the
same way as a C compiler does for C. What it does is to archive and encrypt
your MATLAB code (note, it properly encrypts it, not just pcodes it as a
comment suggests), create a thin executable wrapper and package them
together, possibly also with MATLAB Compiler Runtime (MCR). MCR is very
similar to MATLAB itself, without a graphical user interface, and is freely
redistibutable.
When you run the executable, it dearchives and decrypts your MATLAB code
and runs it against the MCR. It should run exactly the same, both in terms
of results and speed.
Very old versions of MATLAB Compiler (preversion 4.0) work

Launching Matlab from java ProcessBuilder, Matlab console doesn't appear in Mac OS 10.8 
You need to specify that MATLAB is to run with a visible UI by making use
of the desktop flag. I don't believe this is documented.
So the command you need to run is
matlab desktop r "initMatlab;runJavaUI;"
I've created a Java library called matlabcontrol that can abstract all of
this away from you. It can launch MATLAB while running on Windows, OS X,
and Linux and then allow you to interact with MATLAB via eval and feval
commands. matlabcontrol's code to launch MATLAB is located in
matlabcontrol.RemoteMatlabProxyFactory's createProcess(...) method. If you
make use of matlabcontrol as a Java library you won't directly interact
with either this class or this method.

How to apply a trained Matlab neural network from C++ without call to Matlab? 
Of course it is possible  neural networks are clear mathematical models.
All you need is a compatible representation, where you have stored:
network topology (number of neurons in particuluar layers)
network weights (between all neurons)
network activation functions (for each neuron)
And that's all. The exact solution depends on what matlab library you are
using for neural networks. There is a "standard" for prediction models
called PMML, which can be loaded by for example Weka libraries. Either way
 it is easy operation, so you can also implement it by hand by simply
storing all the numbers in the text file and simulating network in the C++
(as the "forward" phase of the neural network is just few lines of code 
the training part is the long one).

Matlab: Improper index matrix reference (or outsmarting matlab) 
In the latest versions of MATLAB (13a/13b) there's a unit testing framework
built in that looks very similar to what you're attempting. Instead of
expect(myfibonacci(0)).toBe(0);
you would write
import matlab.unittest.constraints.IsEqualTo
testCase.verifyThat(myfibonacci(0), IsEqualTo(0))
(You could also/instead have assumeThat, assertThat, or fatalAssertThat).
If for some reason you wish to implement your own framework, note the small
difference in your syntaxes  you have a dot whereas MathWorks have a comma
between myfibonacci(0) and the test condition.
In MATLAB you can't index into the result of a subscripted expression like
that (well, you could, but you would have to overload subsref, and that's a
world of pain, trust me). So the way they've done it is to introduce the
test

Run Matlab executable file with MATLAB Compiler Runtime (MCR) 
It simply means that you don't have rights to run PROGRAM.
What is the output of the command:
ls l PROGRAM
?
Maybe you've compiled this program as a root? Try to change the access
using chmod.

MATLAB: checkmark in MATLAB figure with LaTeX interpreter 
it's not pretty, but might be good enough:
xlabel('$surd$','interpreter','latex')
or look here for other things that look like a tick
http://detexify.kirelabs.org

MATLAB  What are the units of Matlab Camera Calibration Toolbox 
I know next to nothing about matlabs (not entirely true but i avoid matlab
wherever I can, and that would be almost always possible) tracking
utilities but here's some general info.
Pixel dimension on the sensor has nothing to do with the size of the pixel
on screen, or in model space. For all purposes a camera produces a picture
that has no meaningful units. A tracking process is unaware of the scale of
the scene. (the perspective projection takes care of that). You can re
insert a scale by taking 2 tracked points and measuring the distance
between those points. This is the solver spaces distance is pretty much
arbitrary. Now if you know the real distance between these points you can
get a conversion factor. By doing:
real distance / solver space distance.
There's really now way to kno

MatLab>csv: Export data to csv file using dlmwrite in Matlab 
I think the problem is that you write the names to a file at the local
folder and not the other folder.
fldr = fullfile('c:','Data_Analysis');
nomFile=fullfile( fldr, 'Test.csv' );
fid=fopen(nomFile,'w');
fprintf(fid,'%s,',names{:});
fprintf(fid,'
');
dlmwrite(nomFile,A,'append');
fclose(fid);

Conversion of opencv C++ code to Python opencv code 
As Abid commented, I would use cv2 rather than cv module. Since cv2 is
based on c++ interface, you can develop scripts with fewer lines of code
assuming you can do OOP. Another advantage of using cv2 is that python
statement is mostly analogous to its c++ statement
drawing2 = cv2.absdiff(drawing,drawing0)
sc = cv2.sumElems(drawing2)
ar = sc[0] + sc[1] + sc[2]
More details are here

Matlab density plot, Heat map, Matlab 
You can control the colour of each point like so:
scatter(x1, y1, [], C)
where C is the same size as your x1 and y1 matrices. Now if you describe
the rules of how you want this heatmap colour modulation to happen, we can
help you construct C from x1 and y1...

How to get the Matlab workspace associated with the current Matlab project in C#? 
I have already the solution, the way is the next:
Create a .m file (for example SaveWorskpace.m) con this information:
save test.mat
Add SaveWorskpace.m at the project with Matlab Compiler Deployment Tool.
Compile the project with Matlab Compiler Deployment Tool
Add reference at the c# project
Call function SaveWorkspace()
Ready, you have variables save in the workspace test.mat

Call matlab from c++ using VS2010 and matlab 2007a 
This is probably very late reply but this sample code of mine may help you.
#include<iostream>
#include<math.h>
#include<engine.h>
#pragma comment (lib, "libmat.lib")
#pragma comment (lib, "libmx.lib")
#pragma comment (lib, "libmex.lib")
#pragma comment (lib, "libeng.lib")
using namespace std;
const int N = 9; //Number of grid points
int main()
{
// start matlab engine
Engine *ep = engOpen(NULL);
if (!(ep = engOpen(""))) {
fprintf(stderr, "
Can't start MATLAB engine
");
return EXIT_FAILURE;
}
int i, j;
// Grid creation with aspect ratio r
double sum_r = 0, r = 1;
for (i = 0; i < N1; i++){
sum_r += pow(r,i);
}
double dx0 = 1 / sum_r; // calculate first dx
double dy0 =

How to use Matlab from JAVA without using the Matlab Compiler 
If you have Matlab (but you don't have builderJA) then you can use
matlabcontrol for using matlab functions in java.(There might be other
alternatives too, but I don't know)
If you don't have Matlab at all then you can "create the java version of
the matlab function" in some other computer having Matlab and builderJA
installed, and use the jar files in your own computer. You only need to
have MCR (Matlab Compiler Runtime Its FREE) installed on your computer.
Strickly answering your question:
Is there a way to do use Matlab from JAVA, but without the need to
have the Matlab Compiler?
The answer is:
Yes, you can use it. Using matlabcontrol (A java API to interact with
Matlab).

compile a matlab gui for win 32 system using 64 bit win and MATLAB 
As far as I know you cannot actually use 64 bit matlab to build a 32 bit
program.
When I faced the same situation, Mathworks recommended me to (also) install
32 bit matlab on my 64 bit windows. I did not try it, but that should
allow you to build 32 bit programs again.

MATLAB Compiler vs MATLAB Coder 
I'm not an expert, but the Coder is described as generating standalone
C/C++ code, making no mention of the MCR. I notice however that it says
that it only supports a "subset" of the Matlab language, which you can read
more about here. The Compiler appears to just package up your Matlab code
as you suggested, so probably supports most features.

Converting MATLAB 'imagesc' function to work with R's 'imagesc' from R's 'matlab' library 
As I read the question and the linked material and some other material
found with Google, you want the combined capacities of the image and axis
functions in R. Some of the other material said that imagesc really only
relabels the axis annotation. (And it has some additional color scaling
capacity that you don't seem to be requesting.) Reading images in from
files may take some extra packages. There is a grImport package with useful
capabilities for pdf. There are also packages that specialize in particular
formats, eg. tiff or rtiff. If you have a modes sized matrix to plot, you
should offer dput(mat). In the absence of an example and specific
directions can offer this adaptation of an example in the middle of the
Examples section of ?image.
> image(t(volcano)[ncol(volcano):1,]) #

AAM and ASM with opencv 2.4.3 
You can get AAM and ASM code in vosm library but this is not the best way
to find face ROI. Haar cascades much better for this task. AAM and ASM
usually used for finding facial feature points, and they need already
defined face region. Another ASM code you can find here:
https://github.com/MasteringOpenCV/code (see chapter 6).

Qt with OpenCv does nothing 
I'm not sure, if this will help you, but lets give a try...
First, in my programs I use the bars '/' instead of '\'.
Second I never put .dll at libs. I use something like this:
LIBS += LC:/OpenCV/lib/ llibopencv_core245 llibopencv_highgui245
llibopencv_imgproc245
Try to do those changes and then 'run qmake' and 'rebuild all', if you are
using the qtcreator.

getting ROI in OpenCV 
You have the coordinates of the 4 corners of the distorted chessboard. Use
these to find the equations for the 4 lines that form the quadrilateral.
For any given point, you will then be able to check if it lies between the
top and bottom lines and between the left and right lines. If it does, mark
it as 1 on a mask image, else 0. Use the mask image to cut out the
distorted region.

OpenCV RTP Decoding 
you will need an RTP depayloader for your specific stream.
RTP (being targeted at UDP  that is: packet oriented protocols) does not
have a 1:1 mapping between packets (as transmitted) and frames. most of the
time, a single frame will be transmitted via several packets (an ethernet
frame (not to be confused with your image frame) is usually limited to
about 1500 bytes, which makes only tiny images...)
splitting and reassambling your payload chunks into/from network packets is
the task of the RTP payloader resp. depayloader.
the easiest way to do this is probably via gstreamer, which already
provides (de)payloaders for h.264

opencv  rgb value keeps changing 
I am not sure how did you achieve type casting from IplImage to int
int total = (int)(blue[i]) + (int)(green[i]) + (int)(red[i]);
but you certainly need to use pixel by pixel summation for each channel
(not image by image) to find the overall values.

Qt4 or Qt5 (mingw) and openCV 2.4.6 
I managed to configure a Qt Creator project with OpenCV to run a simple
OpenCV application I wrote recently, named cvDisplacementMapFilter.
I tested it with OpenCV 2.4.7 on Mac OS X 10.7.5 and OpenCV 2.4.2 on
Windows 7. I believe the following .pro file can help you:
SOURCES +=
main.cpp
# On my system I have to specify g++ as compiler else it will use clang++
by default
QMAKE_CXX=g++
QMAKE_CC=gcc
## OpenCV settings for Unix/Linux
unix:!mac {
message("* Using settings for Unix/Linux.")
INCLUDEPATH += /usr/local/include/opencv
LIBS += L/usr/local/lib/
lopencv_core
lopencv_highgui
lopencv_imgproc
}
## OpenCV settings for Mac OS X
macx {
message("* Using settings for Mac OS X.")
INCLUDEPATH += /usr/local/include/opencv
LIBS +=

OpenCV C++ to C conversion 
It seems like porting C++ program to C. As per Wikipedia, there are C
interfaces which you can look for your purpose.
Declarations seems right provided the parameters are not reference but
pointers since C does not support reference.
You can use pointers to wrap the class objects. It will be like:
CvMat * cv2dRotationMatrix( CvPoint *, CvAngle *, float );
As you have pointed out that you need to wrap C++ functions under a pure C
function.

OpenCV = operator 
It explains in the link you provided.
Mat& Mat::operator = (const Mat& m)
m :The assigned, righthandside matrix. Matrix assignment is O(1)
operation, that is, no data is copied. Instead, the data is shared and the
reference counter, if any, is incremented. Before assigning new data, the
old data is dereferenced via Mat::release .

OpenCV and convexityDefects 
So i found the answer i was looking for.....
The libraries i used to compile my project where in wrong location.
so i used pkgconfig libs cflags opencv to find exactly where are my
libs....
After that i included these libraries in CodeBlocks and everything magicly
started to work.

Is there a way to disable TBB in openCV? 
Try setNumThreads(0), or for a more thorough solution, try recompiling the
libraries as described here.
