POLAR: Regrid an Image into Polar Coordinates

Form: POLAR dest source [PA=f] [E=e] [C=(r,c)] [NORM] [SINC] [R=(rmin,rmax)]
dest
is the destination image buffer. It does not need to exist beforehand.
source
is the image buffer to transform
PA
is PA of object's major axis
E
gives its ellipticity = 1-b/a
C
gives its row and column center
NORM
renormalize pixel intensities
SINC
use high-resolution sinc interpolation.
R
gives the radial limits of the new grid

POLAR will transform the image in the `source' buffer from observed Cartesian coordinates (x,y) to polar coordinates (r,theta) in the `dest' buffer. The transformation assumes that the object is intrinsically round and projected into an ellipse in the sky plane with the given position angle, ellipticity (1-b/a) and center.

The SINC keyword instructs ROUND to use high-accuracy sinc interpolation instead of the default bilinear interpolation algorithm.

The NORM keyword is used to renormalize the pixel intensities (surface brightness/pixel) in the transformed image.

The R=(rmin,rmax) keyword is used to specify the radial limits of the r-axis of the polar deprojection. By default, if R= is not given the r-axis will run from 0 to the maximum semi-major axis of the inscribed ellipse.

See Also: ROUND