# \#tapi **URL:** https://forum.opencv.org/tag/tapi/302.md [Latest](https://forum.opencv.org/latest.md) · [Categories](https://forum.opencv.org/categories.md) · [Tags](https://forum.opencv.org/tags.md) --- ## [Umat equivalent of Mat.at() to access specific pixel](https://forum.opencv.org/t/umat-equivalent-of-mat-at-to-access-specific-pixel/5779)
**Author:** [@ehardin](https://forum.opencv.org/u/ehardin)\ **Replies:** 4\ **Last updated:** [October 22, 2021, 7:29pm UTC](https://forum.opencv.org/t/umat-equivalent-of-mat-at-to-access-specific-pixel/5779 "2021-10-22T19:29:15Z")
Using OCV 4.5; C++, Visual Studio 2017; MFC; Windows 10 I am trying to convert some Mat code to UMat. An example line would be myMat.at(i, j) = temp\_s; I get the error that ‘at’ is not a member of Umat. What would… --- ## [OpenCV's T-API facedetect.cpp sample is hella slow and CPU intensive with OpenCL "on"](https://forum.opencv.org/t/opencvs-t-api-facedetect-cpp-sample-is-hella-slow-and-cpu-intensive-with-opencl-on/10189)
**Author:** [@Unix\_Man](https://forum.opencv.org/u/Unix_Man)\ **Replies:** 4\ **Last updated:** [November 14, 2022, 7:13pm UTC](https://forum.opencv.org/t/opencvs-t-api-facedetect-cpp-sample-is-hella-slow-and-cpu-intensive-with-opencl-on/10189 "2022-11-14T19:13:29Z")
Hello, The “ufacedetect.cpp” from T-API folder in samples folder runs super slow after compilation. When running the compiled code, OpenCL can be seen displayed as “ON” while running the compiled code. There is no diffe… --- ## [Unspecified error when merge vector\ into umat, after convert color space](https://forum.opencv.org/t/unspecified-error-when-merge-vector-umat-into-umat-after-convert-color-space/6395)
**Author:** [@zhttp](https://forum.opencv.org/u/zhttp)\ **Replies:** 5\ **Last updated:** [November 29, 2021, 11:09am UTC](https://forum.opencv.org/t/unspecified-error-when-merge-vector-umat-into-umat-after-convert-color-space/6395 "2021-11-29T11:09:26Z")
environment: window 10, c++, opencv 4.5.4(download from this), visual studio 2017, my minimal code: int main() { cv::ocl::setUseOpenCL(true); cv::UMat img = cv::imread("my path to a jpg image").getUMat(cv::ACCESS\_FAS… --- ## [Why does calling ORB\_Impl::detectAndCompute block when using cv::Umat](https://forum.opencv.org/t/why-does-calling-orb-impl-detectandcompute-block-when-using-cv-umat/5917)
**Author:** [@Seng\_Yang](https://forum.opencv.org/u/Seng_Yang)\ **Replies:** 0\ **Last updated:** [October 28, 2021, 4:09am UTC](https://forum.opencv.org/t/why-does-calling-orb-impl-detectandcompute-block-when-using-cv-umat/5917 "2021-10-28T04:09:25Z")
My opencv supports opencl, When I use cv::Mat, ORB::detectAndCompute can be executed normally. However, ORB::detectAndCompute cannot be executed normally when using cv:UMat. my code: UMat img{}; imread(imgName.data(),… --- ## [Cv::undistort gpu acceleration](https://forum.opencv.org/t/cv-undistort-gpu-acceleration/5721)
**Author:** [@Aros](https://forum.opencv.org/u/Aros)\ **Replies:** 8\ **Last updated:** [October 25, 2021, 8:56pm UTC](https://forum.opencv.org/t/cv-undistort-gpu-acceleration/5721 "2021-10-25T20:56:25Z")
Hi, in my app I am using camera calibration and I use cv::undistort to compensate for massive barrel distortion of the camera. It works but it’s kind of too slow to be done real-time with acceptable frame-rate. I’d exp… --- ## [UMat support float32?](https://forum.opencv.org/t/umat-support-float32/5428)
**Author:** [@carter54](https://forum.opencv.org/u/carter54)\ **Replies:** 8\ **Last updated:** [October 11, 2021, 8:17am UTC](https://forum.opencv.org/t/umat-support-float32/5428 "2021-10-11T08:17:23Z")
System information (version) OpenCV =\> 4.5.3 Operating System / Platform =\> Windows 64 Bit Compiler =\> Visual Studio 2019 Detailed description I try to use UMat in cv::bilateralFilter function to optimize the performan…