OpenCV with VizionSDK

Introduction

This article will introduce how to display with OpenCV and control the camera using VizionSDK.
You can download the Sample Code here.

OpenCV Version

These examples use OpenCV version 4.9 or newer.

Load OpenCV and VizionSDK

Import the OpenCV and VizionSDK libraries to support the following examples.

C++

Python

#include "VizionSDK.h"
#include <opencv2/highgui.hpp>

import pyvizionsdk
from pyvizionsdk import VX_UVC_IMAGE_PROPERTIES, VX_IMAGE_FORMAT

import cv2
import numpy as np

Start the device

Discover the device and initial it. Then, set the device format to the minimum size for MJPG format.

C++

Python

// initial the camera
int dev_idx = 0;
auto cam = VxInitialCameraDevice(dev_idx);
VxOpen(cam);

// set format to min size for mjpg format
std::vector<VxFormat> fmt_list;
VxGetFormatList(cam, fmt_list);
int min_width = 1920;
int min_height = 1080;
VxFormat min_fmt;
for (auto fmt : fmt_list) {
    // find MJPG smallest size format
    if (fmt.format == VX_IMAGE_FORMAT::MJPG &&
        fmt.width * fmt.height < min_width * min_height) {
        min_width = fmt.width;
        min_height = fmt.height;
        min_fmt = fmt;
    }
}
 
if (VxSetFormat(cam, min_fmt) == 0) {
    std::cout << "Set Capture Format Success!" << std::endl;
} else {
    std::cout << "Set Capture Format Failed!" << std::endl;
}

# initialize camera device
idx = 0
camera = pyvizionsdk.VxInitialCameraDevice(idx)

# open camera
result = pyvizionsdk.VxOpen(camera)
print("Open camera return code:", result)

# get format
result, format_list = pyvizionsdk.VxGetFormatList(camera)
mjpg_format = None
min_resolution = float('inf')
for format in format_list:
    # get mjpg format and minimum resolution
    if format.format == VX_IMAGE_FORMAT.VX_IMAGE_FORMAT_MJPG:
        resolution = format.width * format.height
        if resolution < min_resolution:
            min_resolution = resolution
            mjpg_format = format
print("Return code:", result)

# set format
result = pyvizionsdk.VxSetFormat(camera, mjpg_format)

Display the image

Use VizionSDK VxGetImage function to retrieve the image data and convert it into OpenCV mat to display in the window.

This example demonstrates how to retrieve the format, set it to a specific format, and display the image in a window.

C++

Python

// start streaming
VxStartStreaming(cam);

// get the min format image
uint8_t* raw_data = new uint8_t[3840 * 2160 * 2];
int raw_size = 0;
VxGetImage(cam, raw_data, &raw_size, 2500);

// retrieve the data into the mat array and display with cv2.imshow()
cv::Mat matImg;
matImg = cv::imdecode(cv::Mat(1, raw_size, CV_8UC1, raw_data), cv::IMREAD_COLOR);
cv::imshow("MJPG Image", matImg);
cv::waitKey(0);
cv::destroyAllWindows();

VxStopStreaming(cam);
VxClose(cam);

# start streaming
result = pyvizionsdk.VxStartStreaming(camera)

# get the MJPG format image
result, image = pyvizionsdk.VxGetImage(camera, 1000, mjpg_format)

# retrieve the data to opencv and display with cv2.imshow()
nparr = np.frombuffer(image, np.uint8)
image = cv2.imdecode(nparr, cv2.IMREAD_COLOR)
cv2.imshow("MJPG Image", image)
cv2.waitKey(0)
cv2.destroyAllWindows()

# stop streaming
pyvizionsdk.VxStopStreaming(camera)
# close camera
pyvizionsdk.VxClose(camera)

OpenCV VideoCapture with VizionSDK

Adjust the image properties by VizionSDK and capture with OpenCV VideoCapture.

This example will show how to set the brightness and capture with the frame displayed in the window.

C++

Python

// capture the video and display with cv2.imshow()
cv::VideoCapture cap;
#ifdef _WIN32
    cap = cv::VideoCapture(dev_idx, cv::CAP_DSHOW);
#else
    cap = cv::VideoCapture(dev_idx);
#endif
cap.set(cv::CAP_PROP_FRAME_WIDTH, min_width);
cap.set(cv::CAP_PROP_FRAME_HEIGHT, min_height);
cv::Mat frameBefore;
cap >> frameBefore;
cv::imshow("Before setting", frameBefore);
cv::waitKey(0);
cv::destroyAllWindows();
cap.release();

// get the brightness
long value;
int flag;
VxGetUVCImageProcessing(cam, VX_UVC_IMAGE_PROPERTIES::UVC_IMAGE_BRIGHTNESS, value, flag);
std::cout << "UVC brightness: " << value << std::endl;

// set the brightness
int result;
result = VxSetUVCImageProcessing(cam, VX_UVC_IMAGE_PROPERTIES::UVC_IMAGE_BRIGHTNESS, 16, flag);
std::cout << "Set UVC brightness return code: " << result << std::endl;

// get the brightness
VxGetUVCImageProcessing(cam, VX_UVC_IMAGE_PROPERTIES::UVC_IMAGE_BRIGHTNESS, value, flag);
std::cout << "After setting UVC brightness: " << value << std::endl;

// capture the video after setting the property and display with cv2.imshow()
#ifdef _WIN32
    cap = cv::VideoCapture(dev_idx, cv::CAP_DSHOW);
#else
    cap = cv::VideoCapture(dev_idx);
#endif
cap.set(cv::CAP_PROP_FRAME_WIDTH, min_width);
cap.set(cv::CAP_PROP_FRAME_HEIGHT, min_height);
cv::Mat frameAfter;
cap >> frameAfter;
cv::imshow("After setting", frameAfter);
cv::waitKey(0);
cv::destroyAllWindows();
cap.release();

VxClose(cam);

# import the platform library for video capture backend selection with cross-platform compatibility
import platform

min_width = mjpg_format.width
min_height = mjpg_format.height

# video capture backend selection for cross-platform campatibility
if platform.system() == 'Windows':
    cap = cv2.VideoCapture(idx, cv2.CAP_DSHOW)
else:
    cap = cv2.VideoCapture(idx)
cap.set(cv2.CAP_PROP_FRAME_WIDTH, min_width)
cap.set(cv2.CAP_PROP_FRAME_WIDTH, min_height)
# Capture frame
ret, frame = cap.read()
cv2.imshow('Before setting', frame)
cv2.waitKey(0)
cv2.destroyAllWindows()
cap.release()

# get the brightness
result, brightness, flag = pyvizionsdk.VxGetUVCImageProcessing(camera, VX_UVC_IMAGE_PROPERTIES.UVC_IMAGE_BRIGHTNESS)
print("UVC brightness:", brightness)
print("Flag:", flag)
print("Return code:", result)

# set the brightness
result = pyvizionsdk.VxSetUVCImageProcessing(camera, VX_UVC_IMAGE_PROPERTIES.UVC_IMAGE_BRIGHTNESS, 16, 0)
print("Set UVC brightness return code:", result)

# get the brightness
result, brightness, flag = pyvizionsdk.VxGetUVCImageProcessing(camera, VX_UVC_IMAGE_PROPERTIES.UVC_IMAGE_BRIGHTNESS)
print("After setting UVC brightness:", brightness)
print("Flag:", flag)
print("Return code:", result)

# captured by opencv
if platform.system() == 'Windows':
    cap = cv2.VideoCapture(idx, cv2.CAP_DSHOW)
else:
    cap = cv2.VideoCapture(idx)

cap.set(cv2.CAP_PROP_FRAME_WIDTH, min_width)
cap.set(cv2.CAP_PROP_FRAME_WIDTH, min_height)
# Capture frame
ret, frame = cap.read()
cv2.imshow('After setting', frame)
cv2.waitKey(0)
cap.release()
cv2.destroyAllWindows()

# close camera
pyvizionsdk.VxClose(camera)

OpenCV with VizionSDK

Introduction

OpenCV Version

Load OpenCV and VizionSDK

Start the device

Display the image

OpenCV VideoCapture with VizionSDK

What's Next