interpolation task in IRAF?

AndrewS · Posted: Sun Mar 18, 2012 1:23 am Post subject: interpolation task in IRAF?

Hi there

can any1 recommend is there a task available in IRAF similar to fixpix except that it could perform types of interpolation other than linear?

Thanks

fitz · Posted: Sun Mar 18, 2012 1:27 am Post subject:

Try IMEDIT

AndrewS · Posted: Wed Mar 28, 2012 3:12 pm Post subject:

I have just a quick follow up question!

When using fixpix, if the gap to interpolate over is equal in both the horizontal and vertical directions, you can specify if you want fixpix to interpolate using either good pixels along a row or along a column (by using a specific value for the flag in the mask.). What I am not sure of though is how fixpix interpolates in the diagonal case, ie. conside a 3X3 block of pixels with good pixels at each of the corners:

G I G
I ..I .. I
G I G

above is my rough attempt at representing, where "G" represents Good pixels and "I" represents pixels to be interpolated over. clearly the "I" pixels on the border will be interpolated over using the adjacent "G" pixels. But what is done for the central pixel? is an interpolatiion done along the two diagonals, ie. all 4 "G" pixels are involved in the interpolation?

fitz · Posted: Thu Mar 29, 2012 4:23 am Post subject:

Unless you specifically set the linterp/cinterp params to specify the direction, the task will attempt to choose the narrowest dimension, or all things being equal, will preferentially work along lines. AFAIK, diagonals aren't ever used.