diff --git a/readme.md b/readme.md
index 7c843e4..5a1ad6c 100644
--- a/readme.md
+++ b/readme.md
@@ -16,7 +16,8 @@ For more details:
 ## Requirements
 This code was tested with Tensorflow 1.0, CUDA 8.0 and Ubuntu 16.04.  
 Training takes about 30 hours with the default parameters on the **kitti** split on a single Titan X machine.  
-You can train on multiple GPUs by setting them with the `--num_gpus` flag, make sure your `batch_size` is divisible by `num_gpus`.
+You can train on multiple GPUs by setting them with the `--num_gpus` flag, make sure your `batch_size` is divisible by `num_gpus`.  
+To evaluate the result with our utils [OpenCV](https://opencv.org/) is required.
 
 ## I just want to try it on an image!
 There is a simple mode `monodepth_simple.py` which allows you to quickly run our model on a test image.