| Description: The segment_quality attribute identifies the resultant or targeted image quality index for on-board ICER data compression. Upon return by the ICER decompress function, the output quantity segment_quality provides an indication of the quality of the reconstructed segment. Specifically, the value returned is a double for which the integer values correspond to attained min loss values, but in general is an interpolation between these values. Thus lower values of segment_quality correspond to higher reconstructed qualities, and a value of indicates lossless compression. Note that the compressed stream does not directly contain the value of min loss that was given to the compressor, but the decompressor does know how far along in the decompression process it got before it ran out of bits; this information is used to determine segment_quality. In rare circumstances the decompressor m ay not be able to determine segment_quality for a segment that it decompresses. In this case it sets segment_quality to 1.0. The reconstructed segment might be either lossy or lossless when this occurs. The technical condition under which a quality value is not determined is that the decompressor runs out of the data for the segment before decoding any bit plane information. |