Thanks.
That still leaves me with…
cv::cuda::blur(inputImageGPU, blurredImageGPU, _objectFindingWindowSize, defaultPoint, cv::BorderTypes::BORDER_DEFAULT);
cv::cuda::blur(sqImageGPU, blurredSqImageGPU, _objectFindingWindowSize, defaultPoint, cv::BorderTypes::BORDER_DEFAULT);
I am moving the code from using cv::blur to cv::cuda::blur. I am am still relatively new to opencv so your comment about the box filter does not mean anything to me.