Create thumbnail using excessive memory

Question

I have the following code to read an image (in a file) and create a thumbnail image, writing it to a file:
BufferedImage originalBufferedImage = ImageIO.read(new File(imagePathAndFileName));
int originalWidth = originalBufferedImage.getWidth();
int originalHeight = originalBufferedImage.getHeight();
double scale = 0;
if (((double)75 / originalWidth) <
((double)75 / originalHeight)) {
scale = (double)75 / originalWidth;
} else {
scale = (double)75 / originalHeight;
int width = (int)(originalWidth * scale);
int height = (int)(originalHeight * scale);
BufferedImage newBufferedImage = new BufferedImage(width, height, originalBufferedImage.getType());
Graphics2D graphics2D = newBufferedImage.createGraphics();
Canvas dummyObserver = new Canvas();
Image scaledImage = originalBufferedImage.getScaledInstance(width, height, Image.SCALE_SMOOTH);
graphics2D.drawImage(scaledImage, 0, 0, dummyObserver);
javax.imageio.ImageIO.write(newBufferedImage, fileType, new File(thumbnailPathAndFileName));
With a 1.9 Megabyte image, the call to ImageIO.read() tries to allocate 15 Megabytes of memory, as seen from the log (obtained in WebSphere 5.1 by setting an ALLOCATION_THRESHOLD limit):
Allocation request for 15085072 bytes
at java.awt.image.DataBufferByte.<init>(DataBufferByte.java:87)
at java.awt.image.ComponentSampleModel.createDataBuffer(ComponentSampleModel.java:430)
at java.awt.image.Raster.createWritableRaster(Raster.java:965)
at javax.imageio.ImageTypeSpecifier.createBufferedImage(ImageTypeSpecifier.java:1146)
at javax.imageio.ImageReader.getDestination(ImageReader.java:2868)
at com.sun.imageio.plugins.jpeg.JPEGImageReader.readInternal(JPEGImageReader.java:914)
at com.sun.imageio.plugins.jpeg.JPEGImageReader.read(JPEGImageReader.java:886)
at javax.imageio.ImageIO.read(ImageIO.java:1413)
at javax.imageio.ImageIO.read(ImageIO.java:1299)
Why does it use 15M to read in an image of 1.9M ? Is there a more efficient way to create thumbnail images?

Answer 1

A 15M image correponds to a 5M-pixel RGB 24-bit image. "ImageIO.read" decodes your 1.9M compressed jpeg (beeing roughly a 5Mpixel image, right?) file to a buffered image of some in-memory RGB 24bit format making it consuming 15M. You can get away with using less memory if you can find some ImageIO plugin returning a BufferedImage of type TYPE_CUSTOM with a compressed in-memory representation of the loaded image.
Regards,
Arvid