It all depends on "how" they deal with the image internally. If they load the whole image and then create a memory bitmap, an 85 Mb PNG file is expanded to a much larger file, 3, 4, 5... times larger. It should probably still be accommodated, but I am just pointing out that looking at the size of the file on the disk doesn't tell the whole story. You may want to contact them directly and ask them.
Imagination is greater than detail - Albert Einstein