How to create a big image file from many tiles in java?

Question

My program produces 10 x 10 tiles images of 3000x3000 pixel, one by one (currently saved to 100 files named image_x_y.jpg)

I want to assemble these 100

Answer 1

I don't know if it is possible without loading everything into memory. You can dump all your images to an uncompressed bmp, and then use some external tool to convert it to jpg.