PRiSM : When image translation could lead to degrade image resolution
You may have noticed that image translation leads to degrade image resolution especially when the mean FWHM accross the image is less than 2 pixels. For instance image 1, is a raw image having 1.85 of median FWHM, if one translate the image using the bilinear classic method, the star get blurred and the Fwhm has increased to a figure of 2.35 pixels. PRISM implements now (Beta 5.01.02) a Bspline translation that limits the image blurring during this process, see image 3, where FWHM is now 2.1
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| 1 . Original Image Median FWHM=1.85 |
2. Bilinéar translation (Alpha Blend) Median FWHM=2.35 |
3. Spline translation Median FWHM=2.10 |
A script has been written to measure the star blurring after translation, using different FWHMs, a plot being acheived , the X axis is the star's FHWM before translation and Y axis the FWHM increase after translation (in % related to the FWHM before translation).
