You need to send them where
To a server, there is a library for this.
Between two instances of a sketch, you can just convert the pixels[] array to byte[], or use getImage() to have a BufferedImage (in the form of a java.awt.Image).

Edit: to convert int[] to byte[], you have various methods, from looping on the array and splitting int to bytes with bit shifting and masking (eg. Convert an int to a byte array with an answer from toxi...), or just using the awesome Java library: Java: How to convert int[] to byte[] (Jon Skeet's answer).