我正在使用openCV 3.1.0（我已经尝试过2.4.9，同样的问题）。我想输出一个HSV垫到jpeg：
** Invoke db:migrate (first_time)
** Invoke environment (first_time)
** Execute environment
** Invoke db:load_config (first_time)
** Execute db:load_config
** Execute db:migrate
** Invoke db:_dump (first_time)
** Execute db:_dump
** Invoke db:structure:dump (first_time)
** Invoke environment
** Invoke db:load_config
** Execute db:structure:dump
I, [2016-06-21T08:09:14.083751 #51538] INFO -- : [Rollbar] Scheduling item
I, [2016-06-21T08:09:14.102300 #51538] INFO -- : [Rollbar] Details: https://rollbar.com/instance/uuid?uuid=fgfffgf (only available if report was successful)
rake aborted!
TypeError: no implicit conversion of nil into String
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/Users/atrthur/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/rake-11.2.2/lib/rake/task.rb:173:in `invoke'
/Users/atrthur/.rbenv/versions/2.3.1/lib/ruby/gems/2.3.0/gems/activerecord-5.0.0.rc1/lib/active_record/railties/databases.rake:59:in `block (2 levels) in <top (required)>'
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Tasks: TOP => db:structure:dump
问题是，当// .. Getting JPEG content into memory
// JPEG to mat
Mat imgBuf=Mat(1, jpegContent, CV_8UC3, jpegSize);
Mat imgMat=imdecode(imgBuf, CV_LOAD_IMAGE_COLOR);
free(jpegContent);
if(imgMat.data == NULL) {
// Some error handling
}
// Now the JPEG is decoded and reside in imgMat
cvtColor(imgMat, imgMat, CV_BGR2HSV); // Converting to HSV
Mat tmp;
inRange(imgMat, Scalar(0, 0, 0), Scalar(8, 8, 8), tmp); // Problem goes here
cvtColor(tmp, imgMat, CV_HSV2BGR);
// Mat to JPEG
vector<uchar> buf;
imencode(".jpg", imgMat, buf, std::vector<int>());
outputJPEG=(unsigned char*)malloc(buf.size());
memcpy(outputJPEG, &buf[0], buf.size());
// ... Output JPEG
cvtColor(tmp, imgMat, CV_HSV2BGR) inRange时，我的程序会失败：
OpenCV错误：cvtColor中的断言失败（scn == 3＆amp;＆amp;（dcn == 3 || dcn == 4）＆amp;＆amp;（depth == CV_8U || depth == CV_32F）） /home/pi/opencv/src/opencv-3.1.0/modules/imgproc/src/color.cpp，第8176行
在抛出＆＃39; cv :: Exception＆＃39;的实例后终止调用 what（）：/ home / pi / opencv / src / opencv-1.3.0 / modules / imgproc / src / color.cpp：8176：error：（ - 1515）scn == 3＆amp;＆amp; （dcn == 3 || dcn == 4）＆amp;＆amp;函数cvtColor中的（depth == CV_8U || depth == CV_32F）
如果我删除了inRange，程序就可以了。我试图删除cvtColor调用，让imencode完成其工作，自动将HSV转换为BGR然后转换为JPEG。这一次，没有更多的断言失败，但我的JPEG图像已损坏，正如GStreamer所抱怨的那样：
gstrtpjpegpay.c（581）：gst_rtp_jpeg_pay_read_sof（）： / GstPipeline：pipeline0 / GstRtpJPEGPay：rtpjpegpay0 警告：来自element / GstPipeline：pipeline0 / GstRtpJPEGPay：rtpjpegpay0：错误的SOF长度为11。
同样，删除inRange也解决了这个问题，它会产生良好的JPEG数据。
那么，我是否正在调用inRange不正确导致图像数据损坏？如果是，使用inRange的正确方法是什么？
答案 0 :(得分：1)
inRange生成单通道二进制矩阵，即CV_8UC1矩阵，其值为0或255。
因此您无法将tmp转换为HSV2BGR，因为源图片tmp没有3个频道。
OpenCV正好告诉你： scn （源频道）不是3。
由于您可能希望保留然后只转换到范围内部分图像的BGR，您可以：
imgMat.setTo(Scalar(0,0,0), ~tmp); cvtColor(imgMat, imgMat, CV_HSV2BGR);