regdiff(7)

💖 RegDiff — wait, the manual calls it regdiff(7) 💖

okay bestie, so this is one of the SAORD Documentation pages, and honestly? it's giving "lore drop." sit down, grab a boba, because we're talking about the differences between Funtools and IRAF regions. 🫶

✨ NAME ✨

RegDiff — Differences Between Funtools and IRAF Regions 🌸

✨ SYNOPSIS ✨

It describes the differences between Funtools/ds9 regions and the old IRAF/PROS regions. that's the whole vibe. no flags, no drama, just tea. 💅

✨ DESCRIPTION ✨

so basically, the Funtools girlies tried to make Funtools regions compatible with their predecessor, IRAF/PROS regions. and for simple regions and simple boolean algebra between regions? there should be no difference between the two implementations at all. slay. ✨

but here's the list of differences and incompatibilities between the two, and yes you need to know all of them:

• If a pixel is covered by two different regions expressions, Funtools assigns the mask value of the first region that contains that pixel. that is, successive regions do not overwrite previous regions in the mask, the way it was back in the day with the original PROS regions. 😭 which means you have to define overlapping regions in the reverse order in which they were defined in PROS. if region N is fully contained within region M, then N should be defined before M, or else it's gonna be "covered up" by the latter. 🙈 this change is necessitated by the use of optimized filter compilation, i.e., Funtools only tests individual regions until a proper match is made.
• The PANDA region has replaced the old PROS syntax where a PIE accelerator was combined with an ANNULUS accelerator using AND. so like, this:

ANNULUS(20,20,0,15,n=4) & PIE(20,20,0,360,n=3)

has been replaced by this:

PANDA(20,20,0,360,3,0,15,4)

because the PROS syntax was inconsistent with the meaning of the AND operator. periodt. 💅

• The meaning of pure numbers (i.e., without format specifiers) in regions has been clarified, and so has the syntax for specifying coordinate systems. 👑 if you want the general discussion on Spatial Region Filtering for more information, go read that.

fr fr, if you're porting old PROS region files over, the first bullet is the one that will humble you. reverse the order. trust. 🫶

✨ SEE ALSO ✨

See funtools(7) for a list of Funtools help pages. 🦋

and that's the whole page, bestie — version 1.4.5, dated April 14, 2011, from the SAORD Documentation crew. iconic behavior honestly, mwah 💋🎀