python - 使用 OpenCV 捕获的显微镜图像的解码问题

Question

我正在尝试从 EVOCAM II Microscope from Vision Engineering 中捕获图像使用 OpenCV。它在其手册中说，它可以使用 USB 3.0 数据线插入计算机，然后用作普通网络摄像头。

因此，我使用这个非常简单的代码片段从相机捕获图像:

import cv2
camera = cv2.VideoCapture(0)
ret, frame = camera.read()
if ret:
   cv2.imwrite('./test.png', frame)

但是，当我应该得到 1920px x 1080px RGB 图片时，我得到的是 640px x 480px 带有奇怪伪像的图像:

我尝试在 VLC 或 AMCap 等其他软件上测试摄像头，但我得到的是 640px x 480px 黑色图像或软件甚至无法开始捕获。

我想知道这是编码问题还是相机如何向计算机声明 本身的问题。

我可以通过修改 OpenCV 中的一些参数来解决这个问题还是有什么不同？

非常感谢您的宝贵时间，

编辑 1:

opencv_version -v 在我的 conda 环境中的输出:

General configuration for OpenCV 3.4.2 =====================================
  Version control:               unknown

  Extra modules:
    Location (extra):            /opt/conda/conda-bld/opencv-suite_1533641454250/work/opencv_contrib-3.4.2/modules
    Version control (extra):     unknown

  Platform:
    Timestamp:                   2018-08-07T11:32:43Z
    Host:                        Linux 2.6.32-696.10.1.el6.x86_64 x86_64
    CMake:                       3.12.0
    CMake generator:             Unix Makefiles
    CMake build tool:            /usr/bin/gmake
    Configuration:               Release

  CPU/HW features:
    Baseline:                    SSE SSE2 SSE3
      requested:                 SSE3
    Dispatched code generation:  SSE4_1 SSE4_2 FP16 AVX AVX2 AVX512_SKX
      requested:                 SSE4_1 SSE4_2 AVX FP16 AVX2 AVX512_SKX
      SSE4_1 (3 files):          + SSSE3 SSE4_1
      SSE4_2 (1 files):          + SSSE3 SSE4_1 POPCNT SSE4_2
      FP16 (1 files):            + SSSE3 SSE4_1 POPCNT SSE4_2 FP16 AVX
      AVX (5 files):             + SSSE3 SSE4_1 POPCNT SSE4_2 AVX
      AVX2 (9 files):            + SSSE3 SSE4_1 POPCNT SSE4_2 FP16 FMA3 AVX AVX2
      AVX512_SKX (1 files):      + SSSE3 SSE4_1 POPCNT SSE4_2 FP16 FMA3 AVX AVX2 AVX_512F AVX512_SKX

  C/C++:
    Built as dynamic libs?:      YES
    C++11:                       YES
    C++ Compiler:                /opt/conda/conda-bld/opencv-suite_1533641454250/_build_env/bin/x86_64-conda_cos6-linux-gnu-c++  (ver 7.2.0)
    C++ flags (Release):         -fvisibility-inlines-hidden -std=c++11 -fmessage-length=0 -march=nocona -mtune=haswell -ftree-vectorize -fPIC -fstack-protector-strong -fno-plt -O2 -pipe -I/home/lucas/anaconda3/envs/p35_gpu_jupyter/include -fdebug-prefix-map=${SRC_DIR}=/usr/local/src/conda/${PKG_NAME}-${PKG_VERSION} -fdebug-prefix-map=${PREFIX}=/usr/local/src/conda-prefix   -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 -Wuninitialized -Winit-self -Wno-narrowing -Wno-delete-non-virtual-dtor -Wno-comment -Wimplicit-fallthrough=3 -Wno-strict-overflow -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -ffunction-sections -fdata-sections  -msse -msse2 -msse3 -fopenmp -O3 -DNDEBUG  -DNDEBUG
    C++ flags (Debug):           -fvisibility-inlines-hidden -std=c++11 -fmessage-length=0 -march=nocona -mtune=haswell -ftree-vectorize -fPIC -fstack-protector-strong -fno-plt -O2 -pipe -I/home/lucas/anaconda3/envs/p35_gpu_jupyter/include -fdebug-prefix-map=${SRC_DIR}=/usr/local/src/conda/${PKG_NAME}-${PKG_VERSION} -fdebug-prefix-map=${PREFIX}=/usr/local/src/conda-prefix   -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 -Wuninitialized -Winit-self -Wno-narrowing -Wno-delete-non-virtual-dtor -Wno-comment -Wimplicit-fallthrough=3 -Wno-strict-overflow -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -ffunction-sections -fdata-sections  -msse -msse2 -msse3 -fopenmp -g  -DDEBUG -D_DEBUG
    C Compiler:                  /opt/conda/conda-bld/opencv-suite_1533641454250/_build_env/bin/x86_64-conda_cos6-linux-gnu-cc
    C flags (Release):           -march=nocona -mtune=haswell -ftree-vectorize -fPIC -fstack-protector-strong -fno-plt -O2 -pipe -I/home/lucas/anaconda3/envs/p35_gpu_jupyter/include -fdebug-prefix-map=${SRC_DIR}=/usr/local/src/conda/${PKG_NAME}-${PKG_VERSION} -fdebug-prefix-map=${PREFIX}=/usr/local/src/conda-prefix   -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 -Wuninitialized -Winit-self -Wno-narrowing -Wno-comment -Wimplicit-fallthrough=3 -Wno-strict-overflow -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -ffunction-sections -fdata-sections  -msse -msse2 -msse3 -fopenmp -O3 -DNDEBUG  -DNDEBUG
    C flags (Debug):             -march=nocona -mtune=haswell -ftree-vectorize -fPIC -fstack-protector-strong -fno-plt -O2 -pipe -I/home/lucas/anaconda3/envs/p35_gpu_jupyter/include -fdebug-prefix-map=${SRC_DIR}=/usr/local/src/conda/${PKG_NAME}-${PKG_VERSION} -fdebug-prefix-map=${PREFIX}=/usr/local/src/conda-prefix   -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 -Wuninitialized -Winit-self -Wno-narrowing -Wno-comment -Wimplicit-fallthrough=3 -Wno-strict-overflow -fdiagnostics-show-option -Wno-long-long -pthread -fomit-frame-pointer -ffunction-sections -fdata-sections  -msse -msse2 -msse3 -fopenmp -g  -DDEBUG -D_DEBUG
    Linker flags (Release):      -Wl,-O2 -Wl,--sort-common -Wl,--as-needed -Wl,-z,relro -Wl,-z,now -Wl,-rpath,/home/lucas/anaconda3/envs/p35_gpu_jupyter/lib -L/home/lucas/anaconda3/envs/p35_gpu_jupyter/lib   
    Linker flags (Debug):        -Wl,-O2 -Wl,--sort-common -Wl,--as-needed -Wl,-z,relro -Wl,-z,now -Wl,-rpath,/home/lucas/anaconda3/envs/p35_gpu_jupyter/lib -L/home/lucas/anaconda3/envs/p35_gpu_jupyter/lib   
    ccache:                      NO
    Precompiled headers:         YES
    Extra dependencies:          dl m pthread rt
    3rdparty dependencies:

  OpenCV modules:
    To be built:                 aruco bgsegm bioinspired calib3d ccalib core datasets dnn dnn_objdetect dpm face features2d flann freetype fuzzy hdf hfs highgui img_hash imgcodecs imgproc java java_bindings_generator line_descriptor ml objdetect optflow phase_unwrapping photo plot python2 python3 python_bindings_generator reg rgbd saliency shape stereo stitching structured_light superres surface_matching text tracking video videoio videostab xfeatures2d ximgproc xobjdetect xphoto
    Disabled:                    js world
    Disabled by dependency:      -
    Unavailable:                 cnn_3dobj cudaarithm cudabgsegm cudacodec cudafeatures2d cudafilters cudaimgproc cudalegacy cudaobjdetect cudaoptflow cudastereo cudawarping cudev cvv matlab ovis sfm ts viz
    Applications:                apps
    Documentation:               NO
    Non-free algorithms:         NO

  GUI: 

  Media I/O: 
    ZLib:                        /home/lucas/anaconda3/envs/p35_gpu_jupyter/lib/libz.so (ver 1.2.11)
    JPEG:                        /home/lucas/anaconda3/envs/p35_gpu_jupyter/lib/libjpeg.so (ver 90)
    WEBP:                        build (ver encoder: 0x020e)
    PNG:                         /home/lucas/anaconda3/envs/p35_gpu_jupyter/lib/libpng.so (ver 1.6.34)
    TIFF:                        /home/lucas/anaconda3/envs/p35_gpu_jupyter/lib/libtiff.so (ver 42 / 4.0.9)
    JPEG 2000:                   /home/lucas/anaconda3/envs/p35_gpu_jupyter/lib/libjasper.so (ver 2.0.14)
    OpenEXR:                     build (ver 1.7.1)
    HDR:                         YES
    SUNRASTER:                   YES
    PXM:                         YES

  Video I/O:
    DC1394:                      NO
    FFMPEG:                      YES
      avcodec:                   YES (ver 58.18.100)
      avformat:                  YES (ver 58.12.100)
      avutil:                    YES (ver 56.14.100)
      swscale:                   YES (ver 5.1.100)
      avresample:                YES (ver 4.0.0)
    GStreamer:                   NO
    libv4l/libv4l2:              NO
    v4l/v4l2:                    linux/videodev.h linux/videodev2.h
    gPhoto2:                     NO

  Parallel framework:            OpenMP

  Trace:                         YES (with Intel ITT)

  Other third-party libraries:
    Intel IPP:                   2017.0.3 [2017.0.3]
           at:                   /opt/conda/conda-bld/opencv-suite_1533641454250/work/build/3rdparty/ippicv/ippicv_lnx
    Intel IPP IW:                sources (2017.0.3)
              at:                /opt/conda/conda-bld/opencv-suite_1533641454250/work/build/3rdparty/ippicv/ippiw_lnx
    Lapack:                      NO
    Eigen:                       YES (ver 3.3.3)
    Custom HAL:                  NO
    Protobuf:                    /home/lucas/anaconda3/envs/p35_gpu_jupyter/lib/libprotobuf.so (3.5.1)

  Python 2:
    Interpreter:                 /opt/conda/conda-bld/opencv-suite_1533641454250/work/py2/bin/python (ver 2.7.15)
    Libraries:                   /opt/conda/conda-bld/opencv-suite_1533641454250/work/py2/lib/libpython2.7m.so (ver 2.7.15)
    numpy:                       /opt/conda/conda-bld/opencv-suite_1533641454250/work/py2/lib/python2.7/site-packages/numpy/core/include (ver 1.11.3)
    packages path:               /opt/conda/conda-bld/opencv-suite_1533641454250/work/py2/lib/python2.7/site-packages

  Python 3:
    Interpreter:                 /opt/conda/conda-bld/opencv-suite_1533641454250/work/py3/bin/python (ver 3.7)
    Libraries:                   /opt/conda/conda-bld/opencv-suite_1533641454250/work/py3/lib/libpython3.7m.so (ver 3.7.0)
    numpy:                       /opt/conda/conda-bld/opencv-suite_1533641454250/work/py3/lib/python3.7/site-packages/numpy/core/include (ver 1.11.3)
    packages path:               /opt/conda/conda-bld/opencv-suite_1533641454250/work/py3/lib/python3.7/site-packages

  Python (for build):            /opt/conda/conda-bld/opencv-suite_1533641454250/work/py2/bin/python

  Java:                          
    ant:                         /usr/bin/ant (ver 1.7.1)
    JNI:                         /usr/lib/jvm/java/include /usr/lib/jvm/java/include/linux /usr/lib/jvm/java/include
    Java wrappers:               YES
    Java tests:                  NO

  Install to:                    /home/lucas/anaconda3/envs/p35_gpu_jupyter
-----------------------------------------------------------------

Answer 1

TL;DR 使用的电缆是 USB 2.0，将其替换为 USB 3.0 解决了 Windows 上的捕获问题。

是的，我知道这听起来很愚蠢，但我得到这张奇怪图像的原因是 USB 电缆是 2.0 而不是 3.0。由于电缆已经插入相机，我没有费心去验证它，而是将其更改为 3.0 使其立即在相机 Windows 应用程序上运行。该公司还确认 EVO Cam II 使用 DirectShow 格式生成信号。

但是，当比较相机保存在 USB 驱动器上的图像和使用 USB 数据线拍摄的图像时，我意识到质量并不相似。尤其是在我的情况下，使用 USB 数据线捕获的图像质量不够好。因此我不会再往这个方向追了。

但是，对于那些想从我离开的地方继续的人来说，这里有一些视觉工程支持人员给我的链接，让我可以在 Linux 上使用 OpenCV 捕获图像:

1. Webcam DirectShow Properties Page in Python
2. http://videocapture.sourceforge.net/

目前他们还没有直接的解决方案。