Java BufferImage圖檔處理(擷取寬高、截取、轉換灰階圖)
-
- 1. 效果圖
- 2. 源碼
- 參考
這篇部落格将介紹如何使用Java讀取圖檔為byte[]數組,或者BufferedImage及互相轉換,并進行了轉換圖檔為灰階圖,截取部分區域等;
1. 效果圖
原始圖如下:
截取部分區域(右下角櫻桃)彩色圖 VS 截取部分區域并轉灰階圖:
2. 源碼
package com.ocr.util;
import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.File;
import java.io.IOException;
/*************************************
*Class Name: ImageUtils
*Description: <圖檔處理工具類>
*@author: Seminar
*@since 1.0.0
*************************************/
public class ImageUtils {
/**
* byte[] 轉 BufferedImage
*
* @param bytes
* @return
* @throws IOException
*/
public static BufferedImage bytesToBufferedImage(byte[] bytes) throws IOException {
ByteArrayInputStream in = new ByteArrayInputStream(bytes); // 将bytes作為輸入流
BufferedImage image = ImageIO.read(in); //将in作為輸入流,讀取圖檔存入image中,而這裡in可以為ByteArrayInputStream();
return image;
}
/**
* BufferedImage 轉 byte[]
*
* @param image
* @return
* @throws IOException
*/
public static byte[] bufferedImageToBytes(BufferedImage image) throws IOException {
ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
ImageIO.write(image, "jpg", outputStream);
return outputStream.toByteArray();
}
/**
* 讀取圖檔為灰階圖
*
* @param imagePath 圖檔絕對路徑
* @return
* @throws IOException
*/
public static BufferedImage readAsGrayImage(String imagePath) throws IOException {
BufferedImage src = ImageIO.read(new File(imagePath)); //BufferedImage 類的圖檔資源
BufferedImage grayImage = new BufferedImage(src.getWidth(), src.getHeight(), BufferedImage.TYPE_BYTE_GRAY);
for (int i = 0; i < src.getWidth(); i++) {
for (int j = 0; j < src.getHeight(); j++) {
int rgb = grayImage.getRGB(i, j);
grayImage.setRGB(i, j, rgb);
}
}
return grayImage;
}
/**
* 讀取圖檔後截取
*
* @param imagePath 圖檔絕對路徑
* @param width 要截取的圖檔區域寬度
* @param height 要截取的圖檔區域高度
* @return BufferedImage 截取後的圖檔
* @throws IOException
*/
public static BufferedImage cropImage(String imagePath, int width, int height) throws IOException {
BufferedImage src = ImageIO.read(new File(imagePath)); //BufferedImage 類的圖檔資源
BufferedImage crop = src.getSubimage(src.getWidth() - width, src.getHeight() - height, width, height);
return crop;
}
/**
* 圖檔截取并轉灰階圖
*
* @param src 原始圖檔
* @param width 要截取的圖檔區域寬度
* @param height 要截取的圖檔區域高度
* @return BufferedImage 截取後的圖檔
* @throws IOException
*/
public static BufferedImage cropImageToGray(BufferedImage src, int width, int height) throws IOException {
// 圖檔截取
BufferedImage crop = src.getSubimage(src.getWidth() - width, src.getHeight() - height, width, height);
File cropOutputFile = new File("E:\\mat\\mvt\\java-ocr-demo\\images\\crop.jpg");
ImageIO.write(crop, "jpg", cropOutputFile);
// 圖檔轉灰階圖
BufferedImage grayImage = new BufferedImage(width, height, BufferedImage.TYPE_BYTE_GRAY);
for (int i = 0; i < width; i++) {
for (int j = 0; j < height; j++) {
int rgb = crop.getRGB(i, j);
grayImage.setRGB(i, j, rgb);
}
}
// 儲存圖檔到本地
File outputfile = new File("E:\\mat\\mvt\\java-ocr-demo\\images\\crop_gray.jpg");
ImageIO.write(grayImage, "jpg", outputfile);
return crop;
}
public static void main(String[] args) throws IOException {
String imgPath = "E:\\mat\\mvt\\java-ocr-demo\\images\\yt.jpg";
// 讀取圖檔為BufferedImage
BufferedImage bufferedImage = ImageIO.read(new File(imgPath));
// 讀取圖檔為灰階圖
BufferedImage gray = readAsGrayImage(imgPath);
// 截取圖檔區域RGB
BufferedImage crop = cropImage(imgPath, 240,180);
// 截取圖檔區域灰階圖
BufferedImage cropGray = cropImageToGray(bufferedImage, 240,180);
// BufferedImage轉byte[]
byte[] bytes = bufferedImageToBytes(bufferedImage);
// byte[] 轉 BufferedImage
BufferedImage bi = bytesToBufferedImage(bytes);
}
}
參考
- Java 圖像轉灰階圖
- byte[] 與 BufferedImage互轉