public static void resize(File originalImage, File to, int w, int h, boolean keepRatio) {
        try {
            BufferedImage source = ImageIO.read(originalImage);
            int owidth = source.getWidth();
            int oheight = source.getHeight();
            double ratio = (double) owidth / oheight;

            int maxWidth = w;
            int maxHeight = h;

            if (w < 0 && h < 0) {
                w = owidth;
                h = oheight;
            }
            if (w < 0 && h > 0) {
                w = (int) (h * ratio);
            }
            if (w > 0 && h < 0) {
                h = (int) (w / ratio);
            }

            if (keepRatio) {
                h = (int) (w / ratio);
                if (h > maxHeight) {
                    h = maxHeight;
                    w = (int) (h * ratio);
                }
                if (w > maxWidth) {
                    w = maxWidth;
                    h = (int) (w / ratio);
                }
            }

            String mimeType = "image/jpeg";
            if (to.getName().endsWith(".png")) {
                mimeType = "image/png";
            }
            if (to.getName().endsWith(".gif")) {
                mimeType = "image/gif";
            }

            // out
            BufferedImage dest = new BufferedImage(w, h, BufferedImage.TYPE_INT_RGB);
            Image srcSized = source.getScaledInstance(w, h, Image.SCALE_SMOOTH);
            Graphics graphics = dest.getGraphics();
            graphics.setColor(Color.WHITE);
            graphics.fillRect(0, 0, w, h);
            graphics.drawImage(srcSized, 0, 0, null);
            ImageWriter writer = ImageIO.getImageWritersByMIMEType(mimeType).next();
            ImageWriteParam params = writer.getDefaultWriteParam();
            FileImageOutputStream toFs = new FileImageOutputStream(to);
            writer.setOutput(toFs);
            IIOImage image = new IIOImage(dest, null, null);
            writer.write(null, image, params);
            toFs.flush();
            toFs.close();
            writer.dispose();
        } catch (Exception e) {
            throw new RuntimeException(e);
        }
    }
public static void resize ( File originalImage , File to , int w , int h , boolean keepRatio ) { try { BufferedImage source = ImageIO . read ( originalImage ) ; int owidth = source . getWidth ( ) ; int oheight = source . getHeight ( ) ; double ratio = ( double ) owidth / oheight ; int maxWidth = w ; int maxHeight = h ; if ( w < 0 && h < 0 ) { w = owidth ; h = oheight ; } if ( w < 0 && h > 0 ) { w = ( int ) ( h * ratio ) ; } if ( w > 0 && h < 0 ) { h = ( int ) ( w / ratio ) ; } if ( keepRatio ) { h = ( int ) ( w / ratio ) ; if ( h > maxHeight ) { h = maxHeight ; w = ( int ) ( h * ratio ) ; } if ( w > maxWidth ) { w = maxWidth ; h = ( int ) ( w / ratio ) ; } } String mimeType = "image/jpeg" ; if ( to . getName ( ) . endsWith ( ".png" ) ) { mimeType = "image/png" ; } if ( to . getName ( ) . endsWith ( ".gif" ) ) { mimeType = "image/gif" ; } BufferedImage dest = new BufferedImage ( w , h , BufferedImage . TYPE_INT_RGB ) ; Image srcSized = source . getScaledInstance ( w , h , Image . SCALE_SMOOTH ) ; Graphics graphics = dest . getGraphics ( ) ; graphics . setColor ( Color . WHITE ) ; graphics . fillRect ( 0 , 0 , w , h ) ; graphics . drawImage ( srcSized , 0 , 0 , null ) ; ImageWriter writer = ImageIO . getImageWritersByMIMEType ( mimeType ) . next ( ) ; ImageWriteParam params = writer . getDefaultWriteParam ( ) ; FileImageOutputStream toFs = new FileImageOutputStream ( to ) ; writer . setOutput ( toFs ) ; IIOImage image = new IIOImage ( dest , null , null ) ; writer . write ( null , image , params ) ; toFs . flush ( ) ; toFs . close ( ) ; writer . dispose ( ) ; } catch ( Exception e ) { throw new RuntimeException ( e ) ; } }
Resize an image

@param originalImage The image file
@param to            The destination file
@param w             The new width (or -1 to proportionally resize) or the maxWidth if keepRatio is true
@param h             The new height (or -1 to proportionally resize) or the maxHeight if keepRatio is true
@param keepRatio     : if true, resize will keep the original image ratio and use w and h as max
dimensions