For some time I have been using cv::dft() on a large image and it always took about 4-5 seconds. I noticed it now takes about 30 seconds for the same image and I wonder why. I recently recompiled OpenCV, without having saved the original compiler flags, so maybe I am missing a flag now that speeds up the dft function?
This is the current build configuration:
General configuration for OpenCV 3.2.0 =====================================
Version control: unknown
Extra modules:
Location (extra): /home/uname/opencv_contrib-3.2.0/modules
Version control (extra): unknown
Platform:
Timestamp: 2018-09-17T15:22:43Z
Host: Linux 4.4.0-135-generic x86_64
CMake: 3.5.1
CMake generator: Unix Makefiles
CMake build tool: /usr/bin/make
Configuration: RELEASE
C/C++:
Built as dynamic libs?: YES
C++ Compiler: /usr/bin/c++ (ver 5.4.0)
C++ flags (Release): -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wundef -Winit-self -Wpointer-arith -Wshadow -Wsign-promo -Wno-narrowing -Wno-delete-non-virtual-dtor -Wno-comment -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -ffast-math -msse -msse2 -mno-avx -msse3 -mno-ssse3 -mno-sse4.1 -mno-sse4.2 -ffunction-sections -fvisibility=hidden -fvisibility-inlines-hidden -O3 -DNDEBUG -DNDEBUG
C++ flags (Debug): -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wundef -Winit-self -Wpointer-arith -Wshadow -Wsign-promo -Wno-narrowing -Wno-delete-non-virtual-dtor -Wno-comment -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -ffast-math -msse -msse2 -mno-avx -msse3 -mno-ssse3 -mno-sse4.1 -mno-sse4.2 -ffunction-sections -fvisibility=hidden -fvisibility-inlines-hidden -g -O0 -DDEBUG -D_DEBUG
C Compiler: /usr/bin/cc
C flags (Release): -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wundef -Winit-self -Wpointer-arith -Wshadow -Wno-narrowing -Wno-comment -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -ffast-math -msse -msse2 -mno-avx -msse3 -mno-ssse3 -mno-sse4.1 -mno-sse4.2 -ffunction-sections -fvisibility=hidden -O3 -DNDEBUG -DNDEBUG
C flags (Debug): -fsigned-char -W -Wall -Werror=return-type -Werror=non-virtual-dtor -Werror=address -Werror=sequence-point -Wformat -Werror=format-security -Wmissing-declarations -Wmissing-prototypes -Wstrict-prototypes -Wundef -Winit-self -Wpointer-arith -Wshadow -Wno-narrowing -Wno-comment -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -ffast-math -msse -msse2 -mno-avx -msse3 -mno-ssse3 -mno-sse4.1 -mno-sse4.2 -ffunction-sections -fvisibility=hidden -g -O0 -DDEBUG -D_DEBUG
Linker flags (Release):
Linker flags (Debug):
ccache: NO
Precompiled headers: YES
Extra dependencies: /home/uname/anaconda3/lib/libpng.so /home/uname/anaconda3/lib/libtiff.so /usr/lib/x86_64-linux-gnu/libjasper.so /home/uname/anaconda3/lib/libjpeg.so gtk-3 gdk-3 pangocairo-1.0 pango-1.0 atk-1.0 cairo-gobject cairo gdk_pixbuf-2.0 gio-2.0 gobject-2.0 glib-2.0 gthread-2.0 avcodec-ffmpeg avformat-ffmpeg avutil-ffmpeg swscale-ffmpeg /home/uname/anaconda3/lib/libhdf5_hl.so /home/uname/anaconda3/lib/libhdf5.so /usr/lib/x86_64-linux-gnu/librt.so /usr/lib/x86_64-linux-gnu/libpthread.so /home/uname/anaconda3/lib/libz.so /usr/lib/x86_64-linux-gnu/libdl.so /usr/lib/x86_64-linux-gnu/libm.so dl m pthread rt cudart nppc nppial nppicc nppicom nppidei nppif nppig nppim nppist nppisu nppitc npps cublas cufft -L/usr/local/cuda/lib64
3rdparty dependencies: libwebp IlmImf libprotobuf
OpenCV modules:
To be built: cudev core cudaarithm flann hdf imgproc ml reg surface_matching video cudabgsegm cudafilters cudaimgproc cudawarping dnn freetype fuzzy imgcodecs photo shape videoio cudacodec highgui objdetect plot ts xobjdetect xphoto bgsegm bioinspired dpm face features2d line_descriptor saliency text calib3d ccalib cudafeatures2d cudalegacy cudaobjdetect cudaoptflow cudastereo datasets rgbd stereo superres tracking videostab xfeatures2d ximgproc aruco optflow phase_unwrapping stitching structured_light python2 python3
Disabled: world contrib_world
Disabled by dependency: -
Unavailable: java viz cnn_3dobj cvv matlab sfm
GUI:
QT: NO
GTK+ 3.x: YES (ver 3.18.9)
GThread : YES (ver 2.48.2)
GtkGlExt: NO
OpenGL support: NO
VTK support: NO
Media I/O:
ZLib: /home/uname/anaconda3/lib/libz.so (ver 1.2.8)
JPEG: /home/uname/anaconda3/lib/libjpeg.so (ver 80)
WEBP: build (ver 0.3.1)
PNG: /home/uname/anaconda3/lib/libpng.so (ver 1.6.28)
TIFF: /home/uname/anaconda3/lib/libtiff.so (ver 42 - 4.0.6)
JPEG 2000: /usr/lib/x86_64-linux-gnu/libjasper.so (ver 1.900.1)
OpenEXR: build (ver 1.7.1)
GDAL: NO
GDCM: NO
Video I/O:
DC1394 1.x: NO
DC1394 2.x: NO
FFMPEG: YES
avcodec: YES (ver 56.60.100)
avformat: YES (ver 56.40.101)
avutil: YES (ver 54.31.100)
swscale: YES (ver 3.1.101)
avresample: NO
GStreamer: NO
OpenNI: NO
OpenNI PrimeSensor Modules: NO
OpenNI2: NO
PvAPI: NO
GigEVisionSDK: NO
Aravis SDK: NO
UniCap: NO
UniCap ucil: NO
V4L/V4L2: NO/YES
XIMEA: NO
Xine: NO
gPhoto2: NO
Parallel framework: pthreads
Other third-party libraries:
Use IPP: NO
Use IPP Async: NO
Use VA: NO
Use Intel VA-API/OpenCL: NO
Use Lapack: NO
Use Eigen: NO
Use Cuda: YES (ver 9.1)
Use OpenCL: YES
Use OpenVX: NO
Use custom HAL: NO
NVIDIA CUDA
Use CUFFT: YES
Use CUBLAS: YES
USE NVCUVID: NO
NVIDIA GPU arch: 20 30 35 37 50 52 60 61
NVIDIA PTX archs:
Use fast math: YES
OpenCL: <Dynamic loading of OpenCL library>
Include path: /home/uname/opencv-3.2.0/3rdparty/include/opencl/1.2
Use AMDFFT: NO
Use AMDBLAS: NO
Python 2:
Interpreter: /usr/bin/python2.7 (ver 2.7.12)
Libraries: /usr/lib/x86_64-linux-gnu/libpython2.7.so (ver 2.7.12)
numpy: /usr/local/lib/python2.7/dist-packages/numpy/core/include (ver 1.13.0)
packages path: lib/python2.7/dist-packages
Python 3:
Interpreter: /home/uname/anaconda3/bin/python3 (ver 3.5.2)
Libraries: /usr/lib/x86_64-linux-gnu/libpython3.5m.so (ver 3.5.2)
numpy: /home/uname/anaconda3/lib/python3.5/site-packages/numpy/core/include (ver 1.12.1)
packages path: lib/python3.5/site-packages
Python (for build): /usr/bin/python2.7
Java:
ant: NO
JNI: /usr/lib/jvm/default-java/include /usr/lib/jvm/default-java/include/linux /usr/lib/jvm/default-java/include
Java wrappers: NO
Java tests: NO
Matlab: Matlab not found or implicitly disabled
Documentation:
Doxygen: /usr/bin/doxygen (ver 1.8.11)
Tests and samples:
Tests: YES
Performance tests: YES
C/C++ Examples: YES