在Java中将Base64 jpg转换为Base64Tiff

import java.util.Base64;

String base64Jpg = "Base64 jpg字符串";
byte[] jpgBytes = Base64.getDecoder().decode(base64Jpg);

import javax.imageio.ImageIO;
import java.awt.image.BufferedImage;
import java.io.ByteArrayInputStream;
import java.io.IOException;

ByteArrayInputStream inputStream = new ByteArrayInputStream(jpgBytes);
BufferedImage jpgImage = ImageIO.read(inputStream);

BufferedImage tiffImage = new BufferedImage(jpgImage.getWidth(), jpgImage.getHeight(), BufferedImage.TYPE_BYTE_GRAY);
tiffImage.getGraphics().drawImage(jpgImage, 0, 0, null);

import java.io.ByteArrayOutputStream;

ByteArrayOutputStream outputStream = new ByteArrayOutputStream();
ImageIO.write(tiffImage, "tiff", outputStream);
String base64Tiff = Base64.getEncoder().encodeToString(outputStream.toByteArray());