Welcome to iraf.net Friday, March 29 2024 @ 06:44 AM GMT


 Forum Index > Help Desk > Applications New Topic Post Reply
 fconvolve
   
anestis_tziam
 01/21/2015 02:01PM (Read 1616 times)  
+----
Newbie

Status: offline


Registered: 01/14/2015
Posts: 8


I have created a 2nd order psf in daophot. When i do imhead on the psf file i get the following: 4U1543-624_36_sh.fits.psf.1.fits[30,30,6][real]: PSF for image: 4U1543-624_36_sh.fits

I want to use this psf image on the fconvolve task. I tried the following
fconvolve 4U1543-624_1_sh.fits 4U1543-624_36_sh.fits.psf.1.fits out.fits

and i got the following error.

ERROR: FT pkg: illegal number of axes - must be 1 or 2

Any tip on what i have to use in order to complete the convolution?


Here is what i got on epar Thanks a lot in advance

PACKAGE = fourier
TASK = fconvolve

input1 = 4U1543-624_1_sh.fits first input image
input2 = 4U1543-624_36_sh.fits.psf.1.fits input PSF image
output = out.fits output image
(inreal1= yes) use real part of 1st input image?
(inimag1= no) use imaginary part of 1st input image?
(inreal2= yes) use real part of input PSF image?
(inimag2= no) use imaginary part of input PSF image?
(outreal= yes) create real part of output image?
(outimag= no) create imaginary part of output image?
(pad = yes) use sum of sizes of input images?
(inmemor= yes) currently ignored
(len_blk= 256) currently ignored
(verbose= yes) print actual image names?
(mode = al)

 
Profile Email
 Quote
fitz
 01/21/2015 03:33PM  
AAAAA
Admin

Status: offline


Registered: 09/30/2005
Posts: 4040
The image is 3-D so you need to use an image section to specify a 2-D plane to be used, e.g.

cl\$this->_split2($m[0]) fconvolve 4U1543-624_1_sh.fits[*,*,1] 4U1543-624_36_sh.fits.psf.1.fits[*,*,1] .........

to convolve the first slice of each image. Whether that is the appropriate slice to use, or whether you need to do all 6 individually depends on the data.

 
Profile Email
 Quote
anestis_tziam
 01/21/2015 03:39PM  
+----
Newbie

Status: offline


Registered: 01/14/2015
Posts: 8
Thanks a lot. May i ask what is the physical meaning of each slice?


 
Profile Email
 Quote
fitz
 01/21/2015 03:49PM  
AAAAA
Admin

Status: offline


Registered: 09/30/2005
Posts: 4040
I have no idea. Is the input image you used t make the psf also 3-D? What task did you use? What instrument is this? I would have expected an input 3-D image to generate a similar error when making the psf image. Is there a physical meaning to the slices in the input image? If so, then you should use the same image section trick to remake the psf using just the 2-D section needed (i.e. some instruments include variance planes or bad pixel masks in the data which wouldn't be appropriate to use).

 
Profile Email
 Quote
anestis_tziam
 01/21/2015 04:01PM  
+----
Newbie

Status: offline


Registered: 01/14/2015
Posts: 8
The input image is 2-D and it comes from Magic at the Magellan telescope. I constructed the psf using daophot. In daopars i used this setting

PACKAGE = daophot
TASK = daopars

(functio= gauss) Form of analytic component of psf model
(varorde= 2) Order of empirical component of psf model
(nclean = 3) Number of cleaning iterations for computing psf
(saturat= no) Use wings of saturated stars in psf model comput
(matchra= 3.) Object matching radius in scale units
(psfrad = 65.) Radius of psf model in scale units
(fitrad = 20.5) Fitting radius in scale units
(recente= yes) Recenter stars during fit?
(fitsky = no) Recompute group sky value during fit?
(groupsk= yes) Use group rather than individual sky values?
(sannulu= 0.) Inner radius of sky fitting annulus in scale uni
(wsannul= 30.) Width of sky fitting annulus in scale units
(flaterr= 0.75) Flat field error in percent
(proferr= 5.) Profile error in percent
(maxiter= 50) Maximum number of fitting iterations
(clipexp= 6) Bad data clipping exponent
(clipran= 2.5) Bad data clipping range in sigma
(mergera= INDEF) Critical object merging radius in scale units
(critsnr= 1.) Critical S/N ratio for group membership
(maxnsta= 10000) Maximum number of stars to fit
(maxgrou= 60) Maximum number of stars to fit per group
(mode = ql)

 
Profile Email
 Quote
fitz
 01/21/2015 04:06PM  
AAAAA
Admin

Status: offline


Registered: 09/30/2005
Posts: 4040
From the daophot.psf help page:


The output PSF image psfimage is normally a 2D image containing
the image header parameters, "XPSF", "YPSF", "PSFMAG" and "PSFRAD"
which define the centroid, magnitude and size of the PSF model, the
parameters "FUNCTION", "PSFHEIGH", "NPARS", and "PAR#" which define
the analytic component of the PSF, and a single look-up table of
residuals from the analytic fit subsampled by a factor of 2 with
respect to the parent image.

If the DAOPARS parameter varorder = -1, the PSF is fit by the
analytic function and psfimage has no pixel file.

If the DAOPARS parameter varorder = 1 or 2, then two or five
additional lookup tables are computed and psfimage is a 3D image
with 3 or 6 planes respectively. The first two additional look-up
tables contain the first derivatives of the PSF wrt the x and y
positions in the image (varorder = 1), and the next three contains
the second derivatives with respect to x ** 2, xy, and y ** 2
(varorder = 2).

The positions and magnitudes of each of the stars contributing to
the PSF model are also stored in the PSF image header.

 
Profile Email
 Quote
anestis_tziam
 01/21/2015 04:14PM  
+----
Newbie

Status: offline


Registered: 01/14/2015
Posts: 8
So if I understood this correctly, I should run the convolve task twice?

One like this

fconvolve 4U1543-624_1_sh.fits 4U1543-624_36_sh.fits.psf.1.fits[*,*,1]

and then like this

fconvolve 4U1543-624_1_sh.fits 4U1543-624_36_sh.fits.psf.1.fits[*,*,2]


and check which one gives the best result?

 
Profile Email
 Quote
fitz
 01/21/2015 04:52PM  
AAAAA
Admin

Status: offline


Registered: 09/30/2005
Posts: 4040
I think you either mean planes 2 and 3 (the first derivative wrt x and y), or else just the first plane which is the psf image itself. I can't say for sure, I've never used the task in this way.

 
Profile Email
 Quote
   
Content generated in: 0.25 seconds
New Topic Post Reply

Normal Topic Normal Topic
Sticky Topic Sticky Topic
Locked Topic Locked Topic
New Post New Post
Sticky Topic W/ New Post Sticky Topic W/ New Post
Locked Topic W/ New Post Locked Topic W/ New Post
View Anonymous Posts 
Anonymous users can post 
Filtered HTML Allowed 
Censored Content 
dog allergies remedies cialis 20 mg chilblain remedies


Privacy Policy
Terms of Use

User Functions

Login