Face Detect

GoCV

This is a more complete example that opens a video capture device using device “0”. It also uses the CascadeClassifier class to load an external data file containing the classifier data. The program grabs each frame from the video, then uses the classifier to detect faces. If any faces are found, it draws a green rectangle around each one, then displays the video in an output window:

package main

import (
    "fmt"
    "image"
    "image/color"
    "os"
    "strconv"

    "gocv.io/x/gocv"
)

func main() {
    if len(os.Args) < 3 {
        fmt.Println("How to run:\n\tfacedetect [camera ID] [classifier XML file]")
        return
    }

    // parse args
    deviceID, _ := strconv.Atoi(os.Args[1])
    xmlFile := os.Args[2]

    // open webcam
    webcam, err := gocv.VideoCaptureDevice(int(deviceID))
    if err != nil {
        fmt.Println(err)
        return
    }
    defer webcam.Close()

    // open display window
    window := gocv.NewWindow("Face Detect")
    defer window.Close()

    // prepare image matrix
    img := gocv.NewMat()
    defer img.Close()

    // color for the rect when faces detected
    blue := color.RGBA{0, 0, 255, 0}

    // load classifier to recognize faces
    classifier := gocv.NewCascadeClassifier()
    defer classifier.Close()

    if !classifier.Load(xmlFile) {
        fmt.Printf("Error reading cascade file: %v\n", xmlFile)
        return
    }

    fmt.Printf("start reading camera device: %v\n", deviceID)
    for {
        if ok := webcam.Read(&img); !ok {
            fmt.Printf("cannot read device %d\n", deviceID)
            return
        }
        if img.Empty() {
            continue
        }

        // detect faces
        rects := classifier.DetectMultiScale(img)
        fmt.Printf("found %d faces\n", len(rects))

        // draw a rectangle around each face on the original image,
        // along with text identifying as "Human"
        for _, r := range rects {
            gocv.Rectangle(&img, r, blue, 3)

            size := gocv.GetTextSize("Human", gocv.FontHersheyPlain, 1.2, 2)
            pt := image.Pt(r.Min.X+(r.Min.X/2)-(size.X/2), r.Min.Y-2)
            gocv.PutText(&img, "Human", pt, gocv.FontHersheyPlain, 1.2, blue, 2)
        }

        // show the image in the window, and wait 1 millisecond
        window.IMShow(img)
        if window.WaitKey(1) >= 0 {
            break
        }
    }
}