As of OnBase 13, memory usage during printing has been greatly improved. However, when a document contains notes, the extra processing needed to render the notes onto a page requires a certain amount of memory that is dependent on the size, DPI, and bit depth of the source image. In some scenarios, a sufficiently large image will cause the available memory to fragment and will force you to close the Unity Client.
If the issue persists, consider printing through the OnBase Client or scanning images with lower bit depths.