OpenCV Error: Assertion Failed in MixChannels(..) - c++

Question

I'm attempting to convert a MATLAB .mat file to openCV MAT and then applying several masks to those files. I am building from cvmatio source code. I am receiving the following error:
OpenCV Error: Assertion failed (A.size == arrays[i0]->size) in init,
file
/home/derek/Documents/Libraries/opencv-3.0.0-beta/modules/core/src/matrix.cpp,
line 4279 terminate called after throwing an instance of
'cv::Exception' what():
/home/derek/Documents/Libraries/opencv-3.0.0-beta/modules/core/src/matrix.cpp:4279:
error: (-215) A.size == arrays[i0]->size in function init
Here is the source file I've written. It occurs at the line with MixChannels. Note that SrcImage is a 3 channel Mat. lower and upper are the threshold values in an array who's length is equal to the number of channels.
/*
* Mask.cpp
*
* Created on: Mar 16, 2015
* Author: derek
*/
#include <cv.h>
#include <highgui.h>
#include "imgcodecs.hpp"
#include "highgui.hpp"
#include "imgproc.hpp"
using namespace cv;
Mat Mask(Mat SrcImage, double lower[], double upper[]){
int height=SrcImage.rows;
int width=SrcImage.cols;
int depth=SrcImage.depth();
Mat B2d = Mat::ones(height, width,depth);
Mat out(height, width, depth);
Mat outL(height, width, depth);
Mat outU(height,width, depth);
for (int i=1; i< SrcImage.channels(); i=i+1){
int from_to[]={i,1};
mixChannels(&SrcImage, 3, &out, 1, from_to, 1 );
threshold(out, outL, lower[i], 1, THRESH_BINARY);
threshold(out, outU, upper[i], 1, THRESH_BINARY);
bitwise_and(B2d, outL, B2d);
bitwise_and(B2d, outU, B2d);
}
return B2d;
}
Also, here is an excerpt of the actual CV_Assertion error location. As indicated in the error, it occurs at "(A.size == arrays[i0]->size)".
void NAryMatIterator::init(const Mat** _arrays, Mat* _planes, uchar** _ptrs, int _narrays)
{
CV_Assert( _arrays && (_ptrs || _planes) );
int i, j, d1=0, i0 = -1, d = -1;
arrays = _arrays;
ptrs = _ptrs;
planes = _planes;
narrays = _narrays;
nplanes = 0;
size = 0;
if( narrays < 0 )
{
for( i = 0; _arrays[i] != 0; i++ )
;
narrays = i;
CV_Assert(narrays <= 1000);
}
iterdepth = 0;
for( i = 0; i < narrays; i++ )
{
CV_Assert(arrays[i] != 0);
const Mat& A = *arrays[i];
if( ptrs )
ptrs[i] = A.data;
if( !A.data )
continue;
if( i0 < 0 )
{
i0 = i;
d = A.dims;
// find the first dimensionality which is different from 1;
// in any of the arrays the first "d1" step do not affect the continuity
for( d1 = 0; d1 < d; d1++ )
if( A.size[d1] > 1 )
break;
}
else
CV_Assert( A.size == arrays[i0]->size );
if( !A.isContinuous() )
{
CV_Assert( A.step[d-1] == A.elemSize() );
for( j = d-1; j > d1; j-- )
if( A.step[j]*A.size[j] < A.step[j-1] )
break;
iterdepth = std::max(iterdepth, j);
}
}
if( i0 >= 0 )
{
size = arrays[i0]->size[d-1];
for( j = d-1; j > iterdepth; j-- )
{
int64 total1 = (int64)size*arrays[i0]->size[j-1];
if( total1 != (int)total1 )
break;
size = (int)total1;
}
iterdepth = j;
if( iterdepth == d1 )
iterdepth = 0;
nplanes = 1;
for( j = iterdepth-1; j >= 0; j-- )
nplanes *= arrays[i0]->size[j];
}
else
iterdepth = 0;
idx = 0;
if( !planes )
return;
for( i = 0; i < narrays; i++ )
{
CV_Assert(arrays[i] != 0);
const Mat& A = *arrays[i];
if( !A.data )
{
planes[i] = Mat();
continue;
}
planes[i] = Mat(1, (int)size, A.type(), A.data);
}
}

Answer 1

Well it's obviously too late of an answer, but here is the reason why your code failed:
Since your SrcImage is a single Mat with multiple channels, you should'we written:
mixChannels(&SrcImage, 1, &out, 1, from_to, 1 );
(The assert error was related to this, since mixChannels expected 3 Mats, which is 3 times bigger than your Mat.)
Also opencv MixChannels labels channels from 0, not sure if the i=1 was intended, or just a typo.
Cheers!