The image reconstructed after quantization to 4 bits is visibly degraded, but the essential details are still obvious. Consequently, it seems likely that the quantization of UVAI frames will reduce the quality of reconstructed images. The severity of this effect will depend on the dynamic range and contrast of each image. Application to stars Although the UVAI data is less than ideal in several respects there are also mitigating features. Many images contain the Earth and auroral features of interest on a wider background of space and stars.
Star measurements are extremely useful for deblurring, as they are basically point sources.
Any smearing or blurring will be very obvious in the star field, and the success of image reconstruction can be judged by how point-like stars in the final image appear. The nearly uniform background around the stars is also of value, as it provides an additional constraint on reconstruction techniques. Any severe oscillations will be especially apparent in this region and will indicate problems with the reconstruction. A star from frame 23 in orbit 560. Figure 8 shows a star in frame 23 from orbit 560.