Remove watermark from PNG with java

Question

I want to find a method to add and remove a known watermark from image with Java.

I have an image1.png and a watermark watermark.png

I want to find a method to addWatermark(image1, watermark) --> image2.png

And then I want to recover the origin image like this removeWatermark(image2, watermark) --> image1.png

Can anyone give me a suggestion for this problem?

Answer 1

To overlay two images you can just use the following java code:

File path = ... // base path of the images and the result

// load images
BufferedImage image = ImageIO.read(new File(path, "image.png"));
BufferedImage watermark = ImageIO.read(new File(path, "watermark.png"));

// create the new image, size is the max. of both image sizes
int w = Math.max(image.getWidth(), watermark.getWidth());
int h = Math.max(image.getHeight(), watermark.getHeight());
BufferedImage combined = new BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB);

// now just paint both images, preserving the alpha channels
Graphics g = combined.getGraphics();
g.drawImage(image, 0, 0, null);
g.drawImage(watermark, 0, 0, null);

g.dispose();

// Save this as a new image
ImageIO.write(combined, "PNG", new File(path, "combined.png"));

The removal of watermarks, as the previous speakers have already mentioned, is not that easy.