Convert high-resolution images to low-resolution

Question

I am doing a web project on media manager. I upload high resolution images and need to convert these images to low resolution, so that the resulting image is compressed into a smaller size. How is this possible using Java?

Please post source code, if possible.

Thanks, Naveen

Answer 1

not sure if I got it right, but if you want to change the size of an image, the Image class has a getScaledInstance method:

Image theImage = ...
Image scaled = theImage.getScaledInstance(32, -1, Image.SCALE_FAST);

For details see the documentation of Image

Answer 2

I've seen JAI used for this purpose.

Answer 3

You could add an parameter onto your image reader if you don't need to do anything with the high-res image, e.g.

ImageReadParam param = reader.getDefaultReadParam();
param.setSourceSubsampling(4, 4, 0, 0);
img = reader.read(0);

This will skip 3 out of 4 rows/column in the source data.

Answer 4

If you're running on a Linux server with the imagemagick binaries installed, you could just do an Runtime.getRuntime.exec() on /usr/bin/convert. Just make sure you read/write to unique names (you can use File.createTempFile() to ensure that).