how to convert image to byte array in java? [dupli

Question

This question already has an answer here:

• File to byte[] in Java 21 answers

I want to convert an image to byte array and vice versa. Here, the user will enter the name of the image (.jpg) and program will read it from the file and will convert it to a byte array.

Answer 1

Try this code snippet

BufferedImage image = ImageIO.read(new File("filename.jpg"));

// Process image

ImageIO.write(image, "jpg", new File("output.jpg"));

Answer 2

Here is a complete version of code for doing this. I have tested it. The BufferedImage and Base64 class do the trick mainly. Also some parameter needs to be set correctly.

public class SimpleConvertImage {
    public static void main(String[] args) throws IOException{
        String dirName="C:\\";
        ByteArrayOutputStream baos=new ByteArrayOutputStream(1000);
        BufferedImage img=ImageIO.read(new File(dirName,"rose.jpg"));
        ImageIO.write(img, "jpg", baos);
        baos.flush();

        String base64String=Base64.encode(baos.toByteArray());
        baos.close();

        byte[] bytearray = Base64.decode(base64String);

        BufferedImage imag=ImageIO.read(new ByteArrayInputStream(bytearray));
        ImageIO.write(imag, "jpg", new File(dirName,"snap.jpg"));
    }
}

Reference link

Answer 3

Check out javax.imageio, especially ImageReader and ImageWriter as an abstraction for reading and writing image files.

BufferedImage.getRGB(int x, int y) than allows you to get RGB values on the given pixel, which can be chunked into bytes.

Note: I think you don't want to read the raw bytes, because then you have to deal with all the compression/decompression.