java - 将颜色 channel 从 BGR 转换为 RGB

Question

我正在使用 OpenCV 进行视频捕获项目。我已经能够让视频捕捉正常工作，但我想将相机滤镜更改为“常规”光谱，这样香蕉就不是蓝色而是黄色了哈哈。这将是 RGB 光谱。我在我的程序中的 for 循环中进行了转换，但我的相机 View 仍然是 BRG。这是一张图片。

如何让 ImageView 显示“真实”颜色？这是我的代码。

Mat 到图像类

import java.awt.Color;
import java.awt.image.BufferedImage;
import org.opencv.core.Core;
import org.opencv.core.Mat;

public class Mat2Image {
    Mat mat = new Mat();
    private int argb = 0;
    Color c = new Color(argb, true);
    BufferedImage img;
    byte [] dat;

    Mat2Image(){
    }

    public Mat2Image(Mat mat) {
        getSpace(mat);
    }

    public void getSpace(Mat mat) {
        this.mat = mat;
        int w = mat.cols(), h = mat.rows();
        if (dat == null || dat.length != w * h * 3)
            dat = new byte[w * h * 3];
        if (img == null || img.getWidth() != w || img.getHeight() != h || img.getType() != BufferedImage.TYPE_3BYTE_BGR)
            img = new BufferedImage(w, h, BufferedImage.TYPE_3BYTE_BGR);

        int[] holder = new int[w * h];
        holder =  img.getData().getPixels(0, 0, w, h, (int[]) null);
        for (int i = 0; i < dat.length; i++) {

            int blueChannel = (holder[i] & 0xFF0000) >> 4;
            int greenChannel = (holder[i] & 0xFF00) >> 2;
            int redChannel = (holder[i] & 0xFF);
            int rgb = (blueChannel) & (greenChannel << 2) & (redChannel << 4);

            dat[i] = (byte) rgb;
        }
    }   

    BufferedImage getImage(Mat mat) {
        getSpace(mat);
        mat.get(0, 0, dat);
        img.getRaster().setDataElements(0, 0, mat.cols(), mat.rows(), dat);
        return img;
    }
    static {
        System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
    }
}

视频捕捉类

    public class VideoCap {
    static {
        System.loadLibrary(Core.NATIVE_LIBRARY_NAME);
    }
    int currFrame = 0;
    VideoCapture cap;
    Mat2Image mat2Img = new Mat2Image();

    VideoCap() {
        cap = new VideoCapture();
        cap.open(0);
    }

    BufferedImage getOneFrame() {
        currFrame++;
        //currFrame is just to stop the camera of after the running for a bit.
        if (currFrame == 20) {
            cap.read(mat2Img.mat);
            System.exit(0);
        }
        cap.read(mat2Img.mat);

        return mat2Img.getImage(mat2Img.mat);
    }
}

我的 JFrame 类

    public class MyFrame extends JFrame {
    private JPanel contentPane;

    public static void main(String[] args) {
        EventQueue.invokeLater(new Runnable() {
            public void run() {
                try {
                    MyFrame frame = new MyFrame();
                    frame.setVisible(true);
                } catch (Exception e) {
                    e.printStackTrace();
                }
            }
        });
    }

    public MyFrame() {
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        setBounds(100,100,650,490);
        contentPane = new JPanel();
        contentPane.setBorder(new EmptyBorder(5,5,5,5));
        setContentPane(contentPane);
        contentPane.setLayout(null);

        new MyThread().start();
    }

    VideoCap videoCap = new VideoCap();

    public void paint(Graphics g){
        g = contentPane.getGraphics();
        g.drawImage(videoCap.getOneFrame(), 0, 0, this);
    }

    class MyThread extends Thread{
        @Override
        public void run() {
            for (;;){
                repaint();
                try { Thread.sleep(30);
                } catch (InterruptedException e) {    }
            }  
        } 
    }
}

Answer 1

您错误地重新排列了颜色 - 您没有移动足够多的位，您应该使用 OR (|) 而不是 AND (&) 运算符重新组合颜色。

您的代码:

int blueChannel = (holder[i] & 0xFF0000) >> 4;
int greenChannel = (holder[i] & 0xFF00) >> 2;
int redChannel = (holder[i] & 0xFF);
int rgb = (blueChannel) & (greenChannel << 2) & (redChannel << 4);

应该变成:

int blueChannel = (holder[i] & 0xFF0000) >> 16;
int greenChannel = (holder[i] & 0xFF00) >> 8;
int redChannel = (holder[i] & 0xFF);
int rgb = (blueChannel) | (greenChannel << 8) | (redChannel << 16);

编辑

此外，您似乎没有对目标图像使用 int[]，而是对颜色使用 3 字节编码。所以你更有可能需要做:

for (int i = 0; i < holder.length; i++) {
    byte blueChannel = (byte) ((holder[i] & 0xFF0000) >> 16);
    byte greenChannel = (byte) ((holder[i] & 0xFF00) >> 8);
    byte redChannel = (byte) (holder[i] & 0xFF);

    dat[i*3] = redChannel;
    dat[i*3+1] = greenChannel;
    dat[i*3+2] = blueChannel;

但我不清楚是从 BGR 转到 RGB 还是从 RGB 反向转到 BGR。您可能需要更改最后 3 项分配的顺序才能正确执行此操作。