Test images for connected components sequential region labelling.

Test images used in development of multithreaded sequential region labeling.<br>1. A spiral in the <i>xz</i> plane, to test that disconnected foreground chunks are reconnected during collision resolution.<br>2. s10up: A series of images of natural particles, derived from an X-ray microtomography dataset of a geological material or concrete, original author unknown. The smaller images are cropped out of the largest image, without any other transformation. The main value of this image is that there is a single large foreground particle with complex connections, along with a large number of smaller and intermediate-sized particles, with simpler connections.<br>Performance benchmarking results on a dual-CPU Dell T7920 workstation are included in a spreadsheet, performance_test_table.ods, generated using code at Git commit 718c7e.<br>