Preprocessing

The images have already been corrected for bias and flat field effects by the standard STScI pipe-line reduction process. The following steps will be illuminated during the further preprocessing:

• Extraction from data base.
  • Access of the HST archive using the Starview facility. Searching and downloading at least one image (in case of time and opportunity).
  • Reading from local data base of HST images. Conversion from FITS format to Midas format.

• Reconstruction of dithered images (y, b, and v images)
  • Replication a factor 4 of all images (From 512x512 pixels to 2048x2048 pixels)
  • Alignment of images for each filter

• Removal of cosmic ray events from images
  • Adjustment of filter threshold levels

• Averaging of images
  • Usage of mask images to avoid unnecessary image modifications