diff --git a/imgproc/algs/image_encoder.cpp b/imgproc/algs/image_encoder.cpp
index a918bde..2199d78 100644
--- a/imgproc/algs/image_encoder.cpp
+++ b/imgproc/algs/image_encoder.cpp
@@ -99,9 +99,12 @@ std::shared_ptr<std::vector<uchar>> img_encoder::encode(LPPACKIMAGE head, cv::Ma
     }
     else
     {
+        cv::Mat out;
+
+        cv::flip(mat, out, 0);
         ptr.reset(new std::vector<uchar>());
         head->format = fmt_ == ".jpg" ? IMG_FMT_JPEG : IMG_FMT_PNG;
-        cv::imencode(fmt_.c_str(), mat, *ptr, param_);
+        cv::imencode(fmt_.c_str(), out, *ptr, param_);
         head->prc_time = watch.elapse_ms();
         printf("encode to '%s' in %ums: %u\n", fmt_.c_str(), head->prc_time, ptr->size());
     }