Aikawarazu, TOA is offering Discordian calenders (http://sinxpi.wordpress.com/2012/07/02/discordian-calendar-request-thread/). There's a lot of talented artists here (Net, Epi, et al) so I'm thinking it could be worthwhile getting out shit together to offer ten quality visual arts pieces and call it the PDcom Calender. My quality creativity is pretty limited to words so I can't really offer more that inspiration, but there you go.
There are only five seasons. Why ten images?
Also, I tend to do art in the physical world. I don't understand the dimensions he requested.
He breaks each Season into 2 calender spreads (image on top, calender on the bottom). So, that's the 10 images.
The other statements mean:
"at least 583 x 830" -> minimum dimensions are 583x830 pixels (the actual resoultion will depend on the Pixels-Per-Inch when you scan stuff)
"with an aspect ratio of approximately 1:1.42367" -> If the image is 1,000 pixels wide then it should be around 1,424(ish) pixels tall. Example: a 8.5x11 paper has an aspect ratio of (11/8.5 = ) 1:1.294~, an 8x10 photo has an aspect ratio of (10/8 = ) 1:1.25.....