In this post i would like to discuss what happens when cv mat is passed around.
Opencv mat assignment.
The assignment operator and the copy constructor only copies the header.
The assignment operator and the copy constructor only copies the header.
Use a copy constructor or assignment operator where there can be an array or expression on the right side see below.
Suppose a function void a function mat argument change argument.
The underlying matrix of an image may be copied using the clone and copyto functions.
It seems basically assigning by reference.
I noticed that a new data structure cv matx was added to the new opencv version intended for small matrices of known size at compilation time for example.
After you call a function a a is also affected right.
Output image allocation for opencv functions is automatic unless specified otherwise.
Opencv provides the split function to split the 3 channels rgb image into 3 mat objects one per channel.
It passes the number of dimensions 1 to the mat constructor but the created array will be 2 dimensional with the number of columns set to 1.
I m attempting to share an image that is only being used read only across threads.
Consider the following examples 1 where we want to change what the datastructure is note that we are trying to modify the header of the.
The underlying matrix of an image may be copied using the cv mat clone and cv mat copyto functions.
The parameters are the mat object containing the source image and the vector of mat objects representing each rgb channel in reverse order where the first is blue then green and red.
Passing cv mat as argument.
Suppose a has some values in it mat b a.
Opencv matrix does not respect the const modifier.
Often times when we pass cv mat we forget one important thing.
Via a reference counting system opencv s mat matrix.
So mat dims is always 2 can also be 0 when the array is empty.
If i update b a is also affected.
You do not need to think about memory management with opencvs c interface.
Cv matx31f matrix 3x1 of float type checking the documentation i saw that most of matrix operations are available but still i don t see the advantages of using this new type instead of the old cv mat.
