iraf.net

Hi allI'm having trouble making an rgbcolour image with rgbsun..
First thing is I have three images: _I ,_V and _B filters but when I try rgbsun I am told that images must all be of the same size.. images differ by at most one pixel for given dimension eg. one is (1340X1300) and another is (1341X1301). I actually thought that when I used geomap and the parameters xmin/xmax ymin/ymax set to the dimensions of my reference image and subsequently using geotran would automatically resize my images to the dims. of my ref.image...but apparently not, with that in mind can anyone tell me what is the best way to resize an image and hopefully keep the alignment? Also with another set of images (again _I, _V, _B filters), this time the image size is the same for all (1340X1300) when I try rgbsun I am told ERROR: floating point invalid operation..I suspect that this has to do with the fact that my imstats are fairly off the wall eg. MEAN=-3.105E7 MIN=-6.503E13 MAX=1.094E13, can anyone how I can shift all these values so that my MIN=0 and I think that may fix the problem..ThanksAndrew

[quote:7a221dc44a]First thing is I have three images: _I ,_V and _B filters but when I try rgbsun I am told that images must all be of the same size.. images differ by at most one pixel for given dimension eg. one is (1340X1300) and another is (1341X1301). I actually thought that when I used geomap and the parameters xmin/xmax ymin/ymax set to the dimensions of my reference image and subsequently using geotran would automatically resize my images to the dims. of my ref.image...but apparently not, with that in mind can anyone tell me what is the best way to resize an image and hopefully keep the alignment? [/quote:7a221dc44a]You can use image sections to make the sizes the same, e.g. "i.fits[1:1340,1:1300]". You can use this when specifying the image to the task directly, or else IMCOPY out the section to a new image. You'll need to determine where the extra pixel is to keep the alignment, i.e. the section may need to be [2:1341,1:1300] or somesuch so you don't shift the objects by one pixel.[quote:7a221dc44a]
Also with another set of images (again _I, _V, _B filters), this time the image size is the same for all (1340X1300) when I try rgbsun I am told ERROR: floating point invalid operation..I suspect that this has to do with the fact that my imstats are fairly off the wall eg. MEAN=-3.105E7 MIN=-6.503E13 MAX=1.094E13, can anyone how I can shift all these values so that my MIN=0 and I think that may fix the problem.. [/quote:7a221dc44a]Tasks like IMARITH or IMEXPR can be used to scale the values or add a constant, but simply shifting the mean still means your pixels have a range of 10^26 and these values are beiing mapped to at most 256 grey levels.Have a look at the EXPORT task in the DATAIO package as another way to create color images: It allows expressions to be used that let you scale the data independently, e.g. to add a constant, take a sqrt(), divide by 10^9, etc.
See the help page for examples.[/quote]