How to auto crop an image white border in Java?

Question

What's the easiest way to auto crop the white border out of an image in java? Thanks in advance...

Answer 1

If you want the white parts to be invisible, best way is to use image filters and make white pixels transparent, it is discussed here by @PhiLho with some good samples, if you want to resize your image so it's borders won't have white colors, you can do it with four simple loops, this little method that I've write for you does the trick, note that it just crop upper part of image, you can write the rest,

    private Image getCroppedImage(String address) throws IOException{
    BufferedImage source = ImageIO.read(new File(address)) ;

    boolean flag = false ;
    int upperBorder = -1 ; 
    do{
        upperBorder ++ ;
        for (int c1 =0 ; c1 < source.getWidth() ; c1++){
            if(source.getRGB(c1, upperBorder) != Color.white.getRGB() ){
                flag = true;
                break ;
            }
        }

        if (upperBorder >= source.getHeight())
            flag = true ;
    }while(!flag) ;

    BufferedImage destination = new BufferedImage(source.getWidth(), source.getHeight() - upperBorder, BufferedImage.TYPE_INT_ARGB) ;
    destination.getGraphics().drawImage(source, 0, upperBorder*-1, null) ;

    return destination ;
}