Because each of the three A900 images above is 2016 pixels wide, this means that, if printed at 150 pixels per inch, each print would be 13.44 inches wide. Therefore, if the full A900 image width of 6048 pixels is printed at 150 pixels per inch, the print will be 40.32 inches wide.

Some of the printers used by photographers have a maximum print width of say, 19 inches. Therefore, by making three equal-sized prints, the photographer can produce a triptych which has the equivalent print width of a single print that is about, say, 40 inches wide, without the need to use a much larger printer.

If the three images are mounted on photo blocks that are thick enough to stand on their own, the two outer blocks can be turned inwards slightly to give a semi-circular impression of the image that appears to provide more depth.

Of course, you can, if you prefer, split the image into two panels and make a diptych rather than a triptych!

The triptych has been around for a long time as an accepted work of art, as discussed here:

http://en.wikipedia.org/wiki/Triptych

The above article says that the "triptych form arises from early Christian art, and was a popular standard format for altar paintings from the Middle Ages onwards".

A triptych can take the form of one picture split into three parts, as shown above, or it can be three separate compatible pictures displayed together, as shown in this article about the triptychs of Francis Bacon:

http://en.wikipedia.org/wiki/Triptychs_of_Francis_Bacon