SFD images are prepared from long and short exposure FFIs to extend the
dynamic range of a given image to about 
. The program MK_SFD is used
for this purpose. These images are used to make
the SXT ``movie'' and are especially valuable for surveying the data archive.
Users should recognize that the SFD images are automatically prepared on a
production line basis as part of the data reformatting process and should
be alert for artifacts and features which are not of solar origin. Also,
some areas of the images will have smoothed data inserted to replace
saturation-bleed regions.
While, in general the SFD data are quantitatively correct, quantitative analysis should generally resort to the original SFR files which, for a variety of reasons, will often have images which are not made into SFD images. Users wishing to make their own composite images from 2 or 3 images of different exposure are referred to the program SXT_COMPOSITE.