Recommended tweaks for combine and imcombine help files
Jason Quinn wrote on Nov 19, 2009
Couple of recommended help file tweaks for combine and imcombine.
1) When scaling by exposure, combine seems to scale relative to the average exposure time while imcombine seems to scale relative to the first image in the input list. This should be explicitly mentioned in the scaling section of the documentation. And perhaps with a note that the two act differently. (I always use imcombine but some other group members use combine.... is imcombine the more "fundamental" of the two? It says in the help that combine is derived from imcombine but I don't know how much code they share.)
2) The help files for both imcombine and combine in the explanation of the minmax algorithm both talk about
This should be changed because the variables nlow and nhigh are being used inconsistently leading to possible confusion. Perhaps:
Somehow I only just yesterday even realized that the combine tasks change my choices for how many pixels get rejected according to a dynamic formula. Ugh.
3) When exposure scaling is used by combine, by default it seems to look for an "exptime" keyword and there is no way to change it (there is the !keyword mechanism but it acts differently). By contrast, imcombine allows the specification of a exptime keyword. It should say in the documentation, what keyword is used with combine when exposure is chosen.
1) When scaling by exposure, combine seems to scale relative to the average exposure time while imcombine seems to scale relative to the first image in the input list. This should be explicitly mentioned in the scaling section of the documentation. And perhaps with a note that the two act differently. (I always use imcombine but some other group members use combine.... is imcombine the more "fundamental" of the two? It says in the help that combine is derived from imcombine but I don't know how much code they share.)
2) The help files for both imcombine and combine in the explanation of the minmax algorithm both talk about
As an example with 10 input images and specifying nlow=1 and nhigh=2 the fractions to be rejected are nlow=0.1 and nhigh=0.2 and the number rejected as a function of n is:
This should be changed because the variables nlow and nhigh are being used inconsistently leading to possible confusion. Perhaps:
As an example with 10 input images and specifying nlow=1 and nhigh=2 the fractions to be rejected are 0.1 and 0.2, respectively, and the number rejected as a function of n is:
Somehow I only just yesterday even realized that the combine tasks change my choices for how many pixels get rejected according to a dynamic formula. Ugh.
3) When exposure scaling is used by combine, by default it seems to look for an "exptime" keyword and there is no way to change it (there is the !keyword mechanism but it acts differently). By contrast, imcombine allows the specification of a exptime keyword. It should say in the documentation, what keyword is used with combine when exposure is chosen.
Mike Fitzpatrick wrote on Nov 19, 2009
Hi Jason,
I'll leave it to Frank to comment on the specifics, but I've put this on the list for the next release. Thanks.
-Mike
I'll leave it to Frank to comment on the specifics, but I've put this on the list for the next release. Thanks.
-Mike
Last post on Nov 19, 2009