Choose direction of convolution separately from subtraction in 'ppSub'

[Michael Wood-Vasey]

This is a request to add the option to choose the direction of convolution separately from the direction of subtraction in 'ppSub'. The choice of which was is better can be handled by the wrappers that will call 'ppSub'.

Thanks,
Michael

[Michael Wood-Vasey]

Oh, I see, the '-reverse' command does this if one reads the arguments to ppSub as

ppSub imageToNotChange imageToConvolve

with a default output of

outputImage=imageToNotChange-imageToConvolve

but '-reverse' that allows

outputImage=imageToConvolve-imageToNotChange

OK. I guess this addresses the technical ability but the documentation and help message isn't clear that this is what would happen. I suggest then that the help message be changed to clarify this behavior sinc it currently referse to

Usage: ppSub INPUT.fits REFERENCE.fits OUTPUT_ROOT

and everyone will assume REFERENCE.fits primarily means the image to subtract rather than the image to convolve. Alternatively, the structure of the options and behavior could be changed to always subtract OUTPUT=INPUT-REFERENCE but with an option to reverse the image that is _convolved_.

Thanks,
Michael

[Paul Price]

I added a line to the help output that states the sense of the subtraction (in CVS head). Also, perhaps "template" is a better name for the "reference"?

Current help message:

Pan-STARRS PSF-matched image subtraction

Usage: ppSub INPUT.fits REFERENCE.fits OUTPUT_ROOT

[-psf REFERENCE.psf.fitspsflist REFERENCE.list]

This subtracts the convolved REFERENCE from the INPUT, by default.

Optional arguments, with default values:
[...]

[Michael Wood-Vasey]

Thanks.

As far as I'm concerned, "template" and "reference" effectively mean the same thing. The difference (at least in the various groups I've been involved with) is a matter of cultural usage rather than technical distinction. I personally prefer "reference" because to me "template" implies some level of standardization or whatnot, but I don't think it's an important distinction.