android图像LAB空间Lab各通道直方图显示代码

以下是Android中如何在LAB空间中显示各通道的直方图的示例代码：

import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.graphics.Color;
import android.os.Bundle;
import android.support.v7.app.AppCompatActivity;
import android.widget.ImageView;

import com.jjoe64.graphview.GraphView;
import com.jjoe64.graphview.series.BarGraphSeries;
import com.jjoe64.graphview.series.DataPoint;

public class MainActivity extends AppCompatActivity {

    private ImageView imageView;
    private GraphView graphView;

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        imageView = findViewById(R.id.imageView);
        graphView = findViewById(R.id.graphView);

        // 加载图片
        Bitmap bitmap = BitmapFactory.decodeResource(getResources(), R.drawable.test);

        // 将图像转换为LAB空间
        int width = bitmap.getWidth();
        int height = bitmap.getHeight();
        int[] pixels = new int[width * height];
        float[] lab = new float[3];
        float[] lValues = new float[256];
        float[] aValues = new float[256];
        float[] bValues = new float[256];

        for (int i = 0; i < pixels.length; i++) {
            int pixel = pixels[i];
            int r = Color.red(pixel);
            int g = Color.green(pixel);
            int b = Color.blue(pixel);

            // 转换为LAB空间
            Color.RGBToLAB(r, g, b, lab);
            int l = (int) Math.floor(lab[0]);
            int a = (int) Math.floor(lab[1]);
            int b1 = (int) Math.floor(lab[2]);

            // 计算直方图
            lValues[l]++;
            aValues[a + 128]++;
            bValues[b + 128]++;
        }

        // 创建直方图
        BarGraphSeries<DataPoint> lSeries = new BarGraphSeries<>(getHistogramData(lValues));
        BarGraphSeries<DataPoint> aSeries = new BarGraphSeries<>(getHistogramData(aValues));
        BarGraphSeries<DataPoint> bSeries = new BarGraphSeries<>(getHistogramData(bValues));

        // 设置直方图颜色
        lSeries.setColor(Color.BLACK);
        aSeries.setColor(Color.RED);
        bSeries.setColor(Color.BLUE);

        // 显示直方图
        graphView.addSeries(lSeries);
        graphView.addSeries(aSeries);
        graphView.addSeries(bSeries);

        // 显示图像
        imageView.setImageBitmap(bitmap);
    }

    private DataPoint[] getHistogramData(float[] values) {
        DataPoint[] dataPoints = new DataPoint[values.length];
        for (int i = 0; i < values.length; i++) {
            dataPoints[i] = new DataPoint(i, values[i]);
        }
        return dataPoints;
    }
}

需要注意的是，以上示例代码使用了第三方库GraphView来显示直方图，需要在build.gradle中添加以下依赖项：

implementation 'com.jjoe64:graphview:4.2.2'