ColorFilter block gives OpenCV error

[toshan-luktuke]

Running a simple example of ColorFilter gives the following error:

Process Process-1:
Traceback (most recent call last):
  File "/usr/lib/python3.8/multiprocessing/process.py", line 315, in _bootstrap
    self.run()
  File "/usr/lib/python3.8/multiprocessing/process.py", line 108, in run
    self._target(*self._args, **self._kwargs)
  File "/home/toshan/Downloads/Untitled/modules/ColorFilter2001.py", line 19, in main
    hsv = cv2.cvtColor(frame, cv2.COLOR_BGR2HSV)
cv2.error: OpenCV(4.7.0) /io/opencv/modules/imgproc/src/color.simd_helpers.hpp:92: error: (-2:Unspecified error) in function 'cv::impl::{anonymous}::CvtHelper<VScn, VDcn, VDepth, sizePolicy>::CvtHelper(cv::InputArray, cv::OutputArray, int) [with VScn = cv::impl::{anonymous}::Set<3, 4>; VDcn = cv::impl::{anonymous}::Set<3>; VDepth = cv::impl::{anonymous}::Set<0, 5>; cv::impl::{anonymous}::SizePolicy sizePolicy = cv::impl::<unnamed>::NONE; cv::InputArray = const cv::_InputArray&; cv::OutputArray = const cv::_OutputArray&]'
> Invalid number of channels in input image:
>     'VScn::contains(scn)'
> where
>     'scn' is 1

OpenCV version: 4.7.0
OS: Ubuntu 20.04
Circuit Image:

[siddheshsingh26]

Hey, I was working on this issue and I suspect it may be a system-specific problem since I didn't encounter the error as you did.

This is my system configuration:

• OpenCV version: 4.2.0
• OS : Pop_os 20.04

Circuit Image:

Output

Here are the steps I followed:

• First, I created the circuit by using three blocks: the camera and screen block from Drivers->OpenCV, and the color filter from Processing->OpenCV.
• Next, I compiled the main.py file after building the circuit.
• The output displayed the Frame with the blue color filtered out.

[toshan-luktuke]

Hmm, its definitely possible... Let me re-check once

[toshan-luktuke]

So looking into it further, this issue seems to occur when due to simultaneous execution of blocks, the Colour Filter block tries to execute without an image being supplied to it. In this case the if frame == None is not enough and we need to add a new way to check for existence/non-existence of the image object

[toshan-luktuke]

Currently the check:
if frame.shape == () seems to be working fine. However I don't know if this is the best way to check. So this'll need some investigation

[siddheshsingh26]

Yes, I'll try to find another way to this issue if possible.