1. Golang and camera
Golang is an open source programming language developed by Google and released in 2009. It has the characteristics of simplicity, efficiency and concurrency, so it has become the choice of more and more developers. Golang has a rich standard library and third-party packages, making developing a variety of applications very easy and fast.
In the fields of embedded systems, robots, security monitoring, etc., calling cameras for image processing and image transmission is a very common requirement. By using Golang to call the camera, we can implement various applications, such as face recognition, video surveillance, real-time image processing, etc.
Calling a camera is a task involving hardware operations that requires communication and data interaction with the device. Golang provides some powerful libraries and tools that make calling cameras easy and efficient. Here is a description of how to use Golang to call the camera and perform image processing.
Calling the camera can be operated by using the v4l (Video for Linux) library. v4l is a collection of Linux kernel drivers and user space tools for video devices, through which access and control of cameras can be achieved. In Golang, we can use third-party libraries (such as /korandiz/v4l) to easily call the v4l library, thereby implementing operation of the camera.
Using Golang to call the camera can accomplish many interesting tasks. For example, we can obtain the image data of the camera in real time and use the image processing library provided by Golang to perform various operations on the image, such as filtering, edge detection, face recognition, etc. We can also transmit the processed image data to a remote server through the network to realize the image monitoring system. In addition, we can also combine camera images with other sensor data to achieve more complex applications, such as robot navigation, traffic monitoring, etc.
By calling the camera with Golang, we can easily implement various image processing, image transmission and machine vision-related applications. Golang's high performance, concurrency features and rich libraries and tools enable developers to quickly develop efficient and stable camera applications and give full play to their advantages in practical applications.
2. Install Golang and related libraries
First, we need to install Golang and related libraries. Go to the official Golang website to download the binary file for your operating system and follow the installation guide to install it.
After installing Golang, we need to install some libraries for calling the camera. Golang's official library does not directly support the camera function, but there are some third-party libraries that can provide related functions. One of the more popular libraries is v4l, which can be installed through the following command:
go get -u /korandiz/v4l
After the installation is complete, we can start calling the camera using Golang.
3. Call the camera to obtain images
Here is a simple example code that demonstrates how to call the camera using Golang and get image data:
package main
import (
"fmt"
"/korandiz/v4l"
"image"
"image/png"
"os"
)
func main() {
cam, err := ("/dev/video0")
if err != nil {
("Failed to open video device:", err)
return
}
defer ()
err = ((0x56595559), 640, 480) // Set the camera format if err != nil {
("Failed to set format:", err)
return
}
err = () // Start real-time data flow if err != nil {
("Failed to start streaming:", err)
return
}
defer ()
frame, err := () // Get frame data if err != nil {
("Failed to get frame:", err)
return
}
img := ((0, 0, int(()), int(())))
copy(, ())
file, err := ("")
if err != nil {
("Failed to create file:", err)
return
}
defer ()
err = (file, img) // Write image data to file if err != nil {
("Failed to encode image:", err)
return
}
("Image saved as ")
}
The above code first opens the camera device and sets the format of the camera to RGB565 and the resolution is 640x480. Then start the camera's real-time data stream, obtain a frame of image data, and store it as a picture file.
4. Image processing
In addition to getting the original image data of the camera, we can also use Golang for some simple image processing. Golang provides some powerful image processing libraries, such as /disintegration/imaging, which can perform image scaling, cropping, and filtering operations.
Here is a sample code that demonstrates how to use the library to scale and save the camera's image:
package main
import (
"fmt"
"/korandiz/v4l"
"/disintegration/imaging"
"image/png"
"os"
)
func main() {
cam, err := ("/dev/video0")
if err != nil {
("Failed to open video device:", err)
return
}
defer ()
err = ((0x56595559), 640, 480) // Set the camera format if err != nil {
("Failed to set format:", err)
return
}
err = () // Start real-time data flow if err != nil {
("Failed to start streaming:", err)
return
}
defer ()
frame, err := () // Get frame data if err != nil {
("Failed to get frame:", err)
return
}
img := (()) // Create image objects using the imaging library img = (img, 320, 240, ) // Image zoom img = (img) // Convert the image to grayscale
file, err := ("")
if err != nil {
("Failed to create file:", err)
return
}
defer ()
err = (file, img) // Write image data to file if err != nil {
("Failed to encode image:", err)
return
}
("Image saved as ")
}
After obtaining the camera frame data, the above code usesimagingThe library creates an image object, then scales and converts the image into a grayscale image, and finally saves it as an image file.
5. Case example
In practical applications, calling a camera is usually not only to acquire image data, but may also involve various application scenarios such as face recognition and video surveillance. Below are three examples of cases that demonstrate how to use Golang to call the camera to implement different functions.
Case 1: Face Recognition
Using Golang to call the camera for face recognition is one of the common application scenarios. Below is a sample code based on/Kagami/go-faceThe library implements facial recognition function.
package main
import (
"fmt"
"/korandiz/v4l"
"/Kagami/go-face"
"image/png"
"log"
"os"
)
func main() {
// Turn on the camera cam, err := ("/dev/video0")
if err != nil {
("Failed to open video device:", err)
return
}
defer ()
// Set the camera format err = ((0x56595559), 640, 480)
if err != nil {
("Failed to set format:", err)
return
}
// Open the face recognition model rec, err := ("models")
if err != nil {
("Failed to create recognizer: %v", err)
}
defer ()
// Read known faces knownFaces := []{}
for i := 1; i <= 3; i++ {
imgPath := ("known%", i)
img, err := (imgPath)
if err != nil {
("Failed to open image file: %v", err)
}
defer ()
knownImg, err := (img)
if err != nil {
("Failed to decode image file: %v", err)
}
// Extract feature vectors from face images face, err := (knownImg)
if err != nil {
("Failed to recognize face: %v", err)
}
knownFaces = append(knownFaces, )
}
// Real-time recognition of human faces in camera images for {
// Get camera frame data frame, err := ()
if err != nil {
("Failed to get frame:", err)
continue
}
// Convert camera image to face image img := ((), int(()), int(()))
// Extract feature vectors from face images face, err := (img)
if err != nil {
("Failed to recognize face: %v", err)
continue
}
// Draw face frames in camera image for _, r := range face {
rect :=
drawRect((), int(()), int(()), , , , , 255, 0, 0)
}
// Display recognition results if len(face) > 0 {
// Draw face names in camera image drawText((), int(()), int(()), face[0].Annotation, 10, 10, 255, 255, 0)
}
// Display the recognition result image showImage((), int(()), int(()))
}
}
// Draw a rectangular box in the imagefunc drawRect(data []byte, width, height, x1, y1, x2, y2, r, g, b byte) {
for x := x1; x <= x2; x++ {
setPixel(data, width, height, x, y1, r, g, b)
setPixel(data, width, height, x, y2, r, g, b)
}
for y := y1; y <= y2; y++ {
setPixel(data, width, height, x1, y, r, g, b)
setPixel(data, width, height, x2, y, r, g, b)
}
}
// Set image pixel valuefunc setPixel(data []byte, width, height, x, y int, r, g, b byte) {
index := (y*width + x) * 3
if index < 0 || index >= len(data) {
return
}
data[index] = r
data[index+1] = g
data[index+2] = b
}
// Draw text in imagefunc drawText(data []byte, width, height int, text string, x, y, r, g, b byte) {
fontData := []byte{
0x00, 0x18, 0x24, 0x24, 0x3C, 0x24, 0x24, 0x00, // A
0x00, 0x38, 0x24, 0x38, 0x24, 0x24, 0x38, 0x00, // B
0x00, 0x1C, 0x22, 0x20, 0x20, 0x22, 0x1C, 0x00, // C
0x00, 0x38, 0x24, 0x24, 0x24, 0x24, 0x38, 0x00, // D
...
0x00, 0x3C, 0x10, 0x10, 0x10, 0x12, 0x0C, 0x00, // Z
}
for _, c := range text {
if c >= 'A' && c <= 'Z' {
index := int(c-'A') * 8
drawChar(data, width, height, fontData[index:index+8], x, y, r, g, b)
x += 8
}
}
}
// Draw characters in the imagefunc drawChar(data []byte, width, height int, charData []byte, x, y, r, g, b byte) {
for row := 0; row < 8; row++ {
for col := 0; col < 8; col++ {
if (charData[row] >> col & 1) == 1 {
setPixel(data, width, height, x+col, y+row, r, g, b)
}
}
}
}
// Display image windowfunc showImage(data []byte, width, height int) {
// Display image...
}
Case 2: Video surveillance and mobile detection
Using Golang to call the camera for video surveillance and motion detection is another common application scenario. Below is a sample code based on/PeterCxy/go-cvThe library implements video surveillance and motion detection functions.
package main
import (
"fmt"
"/korandiz/v4l"
cv "/PeterCxy/go-cv"
"/PeterCxy/go-cv/cv/cvimgproc"
"image/png"
"os"
)
func main() {
// Turn on the camera cam, err := ("/dev/video0")
if err != nil {
("Failed to open video device:", err)
return
}
defer ()
// Set the camera format err = ((0x56595559), 640, 480)
if err != nil {
("Failed to set format:", err)
return
}
// Process video streaming for {
// Get camera frame data frame, err := ()
if err != nil {
("Failed to get frame:", err)
continue
}
srcImg := (int(()), int(()), cv.MatTypeCV8UC3, ())
grayImg := ()
(srcImg, grayImg, )
// Conduct motion detection // ...
// Display image window showImage((), int(()), int(()))
}
}
// Display image windowfunc showImage(data []byte, width, height int) {
// Display image...
}
Case 3: Real-time image processing and image transmission
Another common application is real-time image processing and image transmission. Below is a sample code that demonstrates how to use Golang to call the camera for real-time image processing and transmit the processed images over the network.
package main
import (
"fmt"
"/korandiz/v4l"
"/disintegration/imaging"
"image/png"
"net"
"os"
)
func main() {
// Turn on the camera cam, err := ("/dev/video0")
if err != nil {
("Failed to open video device:", err)
return
}
defer ()
// Set the camera format err = ((0x56595559), 640, 480)
if err != nil {
("Failed to set format:", err)
return
}
// Process video streaming for {
// Get camera frame data frame, err := ()
if err != nil {
("Failed to get frame:", err)
continue
}
img := (())
// Perform image processing // ...
// Display image window showImage((), int(()), int(()))
// Send the processed image to the remote server err = sendImage(img, "192.168.0.100:8080")
if err != nil {
("Failed to send image:", err)
continue
}
}
}
// Display image windowfunc showImage(data []byte, width, height int) {
// Display image...
}
// Send images to remote serverfunc sendImage(img , serverAddr string) error {
conn, err := ("tcp", serverAddr)
if err != nil {
return err
}
defer ()
err = (conn, img)
if err != nil {
return err
}
return nil
}
The above three examples demonstrate how to use Golang to call the camera to achieve different application scenarios such as face recognition, video surveillance and real-time image processing. By combining Golang's powerful libraries and tools, we can flexibly develop a variety of camera-related applications.
Summarize
This article describes how to use Golang to call the camera and perform image processing. Through Golang and some related libraries, we can easily obtain the image data of the camera and perform various processing on it. Golang's simplicity, efficiency and easy to learn make it one of the preferred programming languages for developers. Not only that, Golang also provides a rich standard library and third-party library, making it simple and efficient to develop image processing applications. Whether it is developing smartphone applications or security monitoring systems, Golang is a good choice. Hope this article will be helpful to developers who use Golang to call cameras!
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