how to convert image to byte array in java?

Question

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.

Solution 1

BufferedImage consists of two main classes: Raster & ColorModel. Raster itself consists of two classes, DataBufferByte for image content while the other for pixel color.

if you want the data from DataBufferByte, use:

public byte[] extractBytes (String ImageName) throws IOException {
 // open image
 File imgPath = new File(ImageName);
 BufferedImage bufferedImage = ImageIO.read(imgPath);

 // get DataBufferBytes from Raster
 WritableRaster raster = bufferedImage .getRaster();
 DataBufferByte data   = (DataBufferByte) raster.getDataBuffer();

 return ( data.getData() );
}

now you can process these bytes by hiding text in lsb for example, or process it the way you want.

Solution 2

If you are using JDK 7 you can use the following code..

import java.nio.file.Files;
import java.io.File;

File fi = new File("myfile.jpg");
byte[] fileContent = Files.readAllBytes(fi.toPath())

Solution 3

File fnew=new File("/tmp/rose.jpg");
BufferedImage originalImage=ImageIO.read(fnew);
ByteArrayOutputStream baos=new ByteArrayOutputStream();
ImageIO.write(originalImage, "jpg", baos );
byte[] imageInByte=baos.toByteArray();

Solution 4

Try this code snippet

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

// Process image

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

Solution 5

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"));
    }
}

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Comments

[Karussell]

if the image is backen by a short array (which was the case for me and a tif image) it will give you a DataBufferShort resulting in a cast exception

[praveen]

for this classes do i need any extra jars?

[RichardK]

No, in Eclipse just use Ctrl + Shift + o.

[BalusC]

Sorry, but this answer is nonsense. Getting bytes from an image file is not different from getting bytes from an arbitrary file. You don't need Java 2D API for this at all. This approach is clumsy and would only be necessary when you're actually interested in manipulating the image in some way (resizing, cropping, colorizing, etc). Just use Files#readAllBytes() or any other sane way you'd usually use on any arbitrary file.

[Wajdy Essam]

the context for image processing.

[mp3por]

How do you convert the bytes back to an image after I have process them ?