Java如何将像素数组转换为RGB单通道独立图片并存储

每个存储在int数组中的像素值为ARGB格式，共4字节，从高位到低位依次对应：

• 8位alpha透明度通道
• 8位红色通道
• 8位绿色通道
• 8位蓝色通道
  提取单通道图像的核心逻辑是：遍历所有像素，仅保留目标通道的色值，将其余两个颜色通道的值置为0，保留不透明alpha值，最终将处理后的像素数组写入新的图片文件即可。

import javax.imageio.ImageIO;
import java.awt.*;
import java.awt.image.BufferedImage;
import java.awt.image.ImageObserver;
import java.awt.image.PixelGrabber;
import java.io.File;
import java.io.IOException;

public class BMPtoArray {
    public static int[] convertToPixels(Image img) {
        int width = img.getWidth(null);
        int height = img.getHeight(null);
        int[] pixel = new int[width * height];

        PixelGrabber pg = new PixelGrabber(img, 0, 0, width, height, pixel, 0, width);
        try {
            pg.grabPixels();
        } catch (InterruptedException e) {
            throw new IllegalStateException("Error: Interrupted Waiting for Pixels");
        }
        if ((pg.getStatus() & ImageObserver.ABORT) != 0) {
            throw new IllegalStateException("Error: Image Fetch Aborted");
        }
        return pixel;
    }

    // 单通道图片生成并存储通用方法
    private static void saveChannelImage(int[] pixels, int width, int height, int channelMask, String outputPath) throws IOException {
        BufferedImage channelImage = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
        for (int i = 0; i < pixels.length; i++) {
            // 保留alpha通道为不透明，仅保留目标通道色值，其余通道置0
            int processedPixel = 0xFF000000 | (pixels[i] & channelMask);
            int x = i % width;
            int y = i / width;
            channelImage.setRGB(x, y, processedPixel);
        }
        ImageIO.write(channelImage, "bmp", new File(outputPath));
    }

    public static void main(String[] args) throws IOException {
        // 读取原图
        File inputFile = new File("C:\\Users\\Mhamd\\Desktop\\3rd year first semester\\Analysis and Coding\\labs\\2.2Java\\src\\circleRGB.bmp");
        BufferedImage image = ImageIO.read(inputFile);
        int width = image.getWidth();
        int height = image.getHeight();
        // 获取像素数组
        int[] pixels = convertToPixels(image);

        // 三个通道的掩码，分别对应红、绿、蓝
        int redMask = 0x00FF0000;
        int greenMask = 0x0000FF00;
        int blueMask = 0x000000FF;

        // 输出路径默认和原图同目录，可自行修改
        String parentPath = inputFile.getParent();
        saveChannelImage(pixels, width, height, redMask, parentPath + File.separator + "red_circle.bmp");
        saveChannelImage(pixels, width, height, greenMask, parentPath + File.separator + "green_circle.bmp");
        saveChannelImage(pixels, width, height, blueMask, parentPath + File.separator + "blue_circle.bmp");
    }
}

• 封装了saveChannelImage通用方法，传入对应颜色通道的掩码即可生成对应单通道图片，避免重复代码
• 掩码0x00FF0000对应红色通道，仅保留原像素的红色分量，绿色、蓝色分量会被置为0，以此类推对应绿色、蓝色的掩码
• 生成的三个单通道图片默认存储在原图所在目录，文件名分别为red_circle.bmp、green_circle.bmp、blue_circle.bmp
• 运行前请确认原图路径配置正确，对应目录有读写权限

内容的提问来源于stack exchange，提问作者Mohammed Hamdoon