Happens when creating a BigImage from a large jpg file (I have not tested other formats). The image is padded in black up to the next multiple of 512 pixels.
For example, I have this 1024x640 pic loaded into a BigImage. When I draw it, there is no horizontal padding (since 1024 is an exact multiple of 512) but there is a good amount of vertical padding (filling pixels 641 to 1024 which is the next multiple of 512). What's annoying is that this padding is opaque black.
Temporary workaround until the bug is resolved:
Take the BigImage object you have created, and call the subImage method on it with the image's dimensions, like this:
BigImage tempImage = new BigImage("field.jpg");
BigImage image = tempImage.getSubImage(0, 0, tempImage.getWidth(), tempImage.getHeight());
The resulting image has no padding, so apparently subImage does something good that the regular image creation does not.