Ask Your Question

imread returns empty mat in examples

asked 2015-08-12 16:07:22 -0500

Yolteotl gravatar image

updated 2015-08-12 18:06:14 -0500


I'm working on a little robot with stereo camera which communicates with a server (to compute depth map / find obstacles)

I want to try the stereo calibration example of OpenCV 3.0. I had some issues to compile it but it looks ok now, ./configure is printing this output :

 -- General configuration for OpenCV 3.0.0-dev =====================================
--   Version control:               3.0.0-283-ge0b327a-dirty
--   Platform:
--     Host:                        Linux 3.16.0-45-generic x86_64
--     CMake:             
--     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 4.8.4)
--     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 -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -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 -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -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 -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -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 -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -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):        
--     Precompiled headers:         YES
--     Extra dependencies:          /usr/lib/x86_64-linux-gnu/ /usr/lib/x86_64-linux-gnu/ /usr/lib/x86_64-linux-gnu/ /usr/lib/x86_64-linux-gnu/ /usr/lib/x86_64-linux-gnu/ /usr/lib/ /usr/lib/x86_64-linux-gnu/ /usr/lib/x86_64-linux-gnu/ /usr/lib/x86_64-linux-gnu/ /usr/lib/x86_64-linux-gnu/ /usr/lib/x86_64-linux-gnu/ gtk-x11-2.0 gdk-x11-2.0 atk-1.0 gio-2.0 pangoft2-1.0 pangocairo-1.0 gdk_pixbuf-2.0 cairo pango-1.0 fontconfig freetype gthread-2.0 gstvideo-1.0 gstapp-1.0 gstbase-1.0 gstriff-1.0 gstpbutils-1.0 gstreamer-1.0 gobject-2.0 glib-2.0 dc1394 avcodec avformat avutil swscale /usr/lib/x86_64-linux-gnu/ dl m pthread rt
--     3rdparty dependencies:       ippicv
--   OpenCV modules:
--     To be built:                 hal core flann imgproc ml photo video imgcodecs shape videoio highgui objdetect superres ts features2d calib3d stitching videostab
--     Disabled:                    java world
--     Disabled by dependency:      -
--     Unavailable:                 cudaarithm cudabgsegm cudacodec cudafeatures2d cudafilters cudaimgproc cudalegacy cudaobjdetect cudaoptflow cudastereo cudawarping cudev python2 python3 viz
--   GUI: 
--     QT:                          NO
--     GTK+ 2.x:                    YES (ver 2.24.23)
--     GThread :                    YES (ver 2.45.4)
--     GtkGlExt:                    NO
--     OpenGL support:              NO
--     VTK support:                 NO
--   Media I/O: 
--     ZLib:                        /usr/lib/x86_64-linux-gnu/ (ver 1.2.8)
--     JPEG:                        /usr/lib/ (ver 62)
--     WEBP:                        /usr/lib ...
edit retag flag offensive close merge delete


Why do you perform fopen in this code? You do not have to fopen an image to imread it.

unxnut gravatar imageunxnut ( 2015-08-12 16:42:04 -0500 )edit

It was just a check to see if the path was good. Of course it's not needed for the normal sample.

Yolteotl gravatar imageYolteotl ( 2015-08-12 16:46:33 -0500 )edit

1 answer

Sort by ยป oldest newest most voted

answered 2015-08-13 18:19:01 -0500

Yolteotl gravatar image

Ok, I found the issue, the configuration took my /usr/lib/ while the linker took another file. Adding "-DBUILD_JPEG=ON -DBUILD_TIFF=ON" to the cmake command made the trick.

Hope it will help other people if they are facing the same problem.

edit flag offensive delete link more

Question Tools

1 follower


Asked: 2015-08-12 16:07:22 -0500

Seen: 916 times

Last updated: Aug 12 '15