Fix for the case where there are no detections (#9784)
Fix for the case where there are no detections (#9784)

Use cv2.cvtColor instead of np to convert from BGR 2 RGB
Fix context in detector
szha/mxnet,apache/incubator-mxnet,dmlc/mxnet,navrasio/mxnet,fullfanta/mxnet,tlby/mxnet,yajiedesign/mxnet,fullfanta/mxnet,ptrendx/mxnet,ForkedReposBak/mxnet,fullfanta/mxnet,dmlc/mxnet,jamesliu/mxnet,reminisce/mxnet,indhub/mxnet,dmlc/mxnet,leezu/mxnet,ptrendx/mxnet,precedenceguo/mxnet,navrasio/mxnet,indhub/mxnet,precedenceguo/mxnet,precedenceguo/mxnet,rahul003/mxnet,DickJC123/mxnet,jamesliu/mxnet,navrasio/mxnet,apache/incubator-mxnet,eric-haibin-lin/mxnet,tlby/mxnet,rahul003/mxnet,ForkedReposBak/mxnet,yajiedesign/mxnet,zhreshold/mxnet,dmlc/mxnet,ForkedReposBak/mxnet,rahul003/mxnet,eric-haibin-lin/mxnet,mbaijal/incubator-mxnet,reminisce/mxnet,dmlc/mxnet,fullfanta/mxnet,ForkedReposBak/mxnet,szha/mxnet,fullfanta/mxnet,indhub/mxnet,indhub/mxnet,rahul003/mxnet,leezu/mxnet,mbaijal/incubator-mxnet,indhub/mxnet,rahul003/mxnet,larroy/mxnet,eric-haibin-lin/mxnet,zhreshold/mxnet,zhreshold/mxnet,tlby/mxnet,jamesliu/mxnet,ptrendx/mxnet,zhreshold/mxnet,DickJC123/mxnet,navrasio/mxnet,navrasio/mxnet,jamesliu/mxnet,leezu/mxnet,larroy/mxnet,sxjscience/mxnet,tlby/mxnet,larroy/mxnet,sxjscience/mxnet,szha/mxnet,reminisce/mxnet,ptrendx/mxnet,tlby/mxnet,ForkedReposBak/mxnet,fullfanta/mxnet,navrasio/mxnet,yajiedesign/mxnet,reminisce/mxnet,apache/incubator-mxnet,dmlc/mxnet,jamesliu/mxnet,apache/incubator-mxnet,larroy/mxnet,eric-haibin-lin/mxnet,precedenceguo/mxnet,ForkedReposBak/mxnet,navrasio/mxnet,sxjscience/mxnet,precedenceguo/mxnet,larroy/mxnet,szha/mxnet,jamesliu/mxnet,ptrendx/mxnet,ptrendx/mxnet,navrasio/mxnet,ptrendx/mxnet,fullfanta/mxnet,zhreshold/mxnet,ptrendx/mxnet,eric-haibin-lin/mxnet,DickJC123/mxnet,ptrendx/mxnet,dmlc/mxnet,mbaijal/incubator-mxnet,rahul003/mxnet,zhreshold/mxnet,reminisce/mxnet,leezu/mxnet,precedenceguo/mxnet,dmlc/mxnet,sxjscience/mxnet,szha/mxnet,eric-haibin-lin/mxnet,ForkedReposBak/mxnet,leezu/mxnet,mbaijal/incubator-mxnet,precedenceguo/mxnet,rahul003/mxnet,sxjscience/mxnet,larroy/mxnet,sxjscience/mxnet,reminisce/mxnet,larroy/mxnet,fullfanta/mxnet,mbaijal/incubator-mxnet,tlby/mxnet,yajiedesign/mxnet,leezu/mxnet,mbaijal/incubator-mxnet,rahul003/mxnet,szha/mxnet,zhreshold/mxnet,tlby/mxnet,mbaijal/incubator-mxnet,szha/mxnet,leezu/mxnet,larroy/mxnet,leezu/mxnet,ForkedReposBak/mxnet,szha/mxnet,indhub/mxnet,jamesliu/mxnet,jamesliu/mxnet,sxjscience/mxnet,leezu/mxnet,reminisce/mxnet,yajiedesign/mxnet,navrasio/mxnet,mbaijal/incubator-mxnet,mbaijal/incubator-mxnet,tlby/mxnet,dmlc/mxnet,yajiedesign/mxnet,precedenceguo/mxnet,DickJC123/mxnet,reminisce/mxnet,yajiedesign/mxnet,ForkedReposBak/mxnet,eric-haibin-lin/mxnet,rahul003/mxnet,szha/mxnet,zhreshold/mxnet,zhreshold/mxnet,yajiedesign/mxnet,ptrendx/mxnet,indhub/mxnet,indhub/mxnet,indhub/mxnet,sxjscience/mxnet,reminisce/mxnet,sxjscience/mxnet,jamesliu/mxnet,reminisce/mxnet,tlby/mxnet,precedenceguo/mxnet,fullfanta/mxnet,tlby/mxnet,yajiedesign/mxnet,eric-haibin-lin/mxnet,larroy/mxnet,eric-haibin-lin/mxnet