If you have an java.awt.Image, rezising it doesn’t require any additional libraries. Just do:
Image newImage = yourImage.getScaledInstance(newWidth, newHeight, Image.SCALE_DEFAULT);
Ovbiously, replace newWidth and newHeight with the dimensions of the specified image.
Notice the last parameter: it tells to the runtime the algorithm you want to use for resizing.
There are algorithms that produce a very precise result, however these take a large time to complete.
You can use any of the following algorithms:
Image.SCALE_DEFAULT: Use the default image-scaling algorithm.
Image.SCALE_FAST: Choose an image-scaling algorithm that gives higher priority to scaling speed than smoothness of the scaled image.
Image.SCALE_SMOOTH: Choose an image-scaling algorithm that gives higher priority to image smoothness than scaling speed.
Image.SCALE_AREA_AVERAGING: Use the Area Averaging image scaling algorithm.
Image.SCALE_REPLICATE: Use the image scaling algorithm embodied in the ReplicateScaleFilter class.
See the Javadoc for more info.
We’re doing this to create thumbnails of images:
BufferedImage tThumbImage = new BufferedImage( tThumbWidth, tThumbHeight, BufferedImage.TYPE_INT_RGB );
Graphics2D tGraphics2D = tThumbImage.createGraphics(); //create a graphics object to paint to
tGraphics2D.setBackground( Color.WHITE );
tGraphics2D.setPaint( Color.WHITE );
tGraphics2D.fillRect( 0, 0, tThumbWidth, tThumbHeight );
tGraphics2D.setRenderingHint( RenderingHints.KEY_INTERPOLATION, RenderingHints.VALUE_INTERPOLATION_BILINEAR );
tGraphics2D.drawImage( tOriginalImage, 0, 0, tThumbWidth, tThumbHeight, null ); //draw the image scaled
ImageIO.write( tThumbImage, “JPG”, tThumbnailTarget ); //write the image to a file