| Re: Scale the psf on images. [message #90012 is a reply to message #89968] |
Wed, 14 January 2015 23:13   |
anes.tziamtzis
Messages: 9
Registered: January 2015
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Junior Member |
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Well perhaps i will get the award for the dumbest person in the world for this.
On the following link there is an fft example
http://www.exelisvis.com/docs/fftreducebackgroundnoise.html
As you said Mats they do something to reduce the noise. The problem is by using this method, again the final image doesnt make sense. There is no structure actually and the pixel values vary from -1e7 to 1e7. This is the code
fits_read, 'Image1.fits',image1,header1
fits_read, 'Image1.fits.psf.1.fits',image2,header2
fits_read, 'Image2.fits',image3,header3
fits_read, 'Image2.fits.psf.1.fits',image4,header4
;Compute the difference kernel
p1=fft(image2)
p2=fft(image4)
; Compute the power spectrum of the transform and apply a log scale.
powerSpectrum = ABS(p1)^2
scaledPowerSpect = ALOG10(powerSpectrum)
powerSpectrum2 = ABS(p2)^2
scaledPowerSpect2 = ALOG10(powerSpectrum2)
; Scale the power spectrum to make its maximum value equal to 0.
scaledPS = scaledPowerSpect - MAX(scaledPowerSpect)
scaledPS2 = scaledPowerSpect2 - MAX(scaledPowerSpect2)
surface,powerSpectrum2
mask = REAL_PART(scaledPowerSpect) GT -5
psf1_trans = p1*mask
mask2 = REAL_PART(scaledPowerSpect2) GT -5
psf2_trans = p2*mask2
kernel = REAL_PART(FFT(psf1_trans/psf2_trans, /INVERSE, /CENTER))
image3_prime = convol(image3, kernel)
diff = image1 - image3_prime
WRITEFITS,'im_conv.fits',diff,header3
end
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