hi2isis

Converts a single channel HiRISE EDR into an Isis Cube file. The observation image data from the EDR is transfered into the Isis Cube data. The observation line prefix and suffix data will be combined into a single Isis table named "HiRISE Ancillary". The calibration image data will be placed into an Isis table named "HiRISE Calibration Image", and the calibration line prefix and suffix data will be combined into a single Isis table named "HiRISE Calibration Ancillary".

8 bit EDR pixels are checked for invalid values in the following order: gaps (255 = 0xFF), high instrument saturation (254 = 0xFE), and low instrument saturation (0 = 0x00). See the following table for what these values are converted to. Once the special pixels have been delt with the 8 bit data is processed in one of two ways depending on the UNLUT parameter. If UNLUT is false then the 8 bit values are simply moved into a signed 16 bit integer without modifying their magnitude. If UNLUT is true, the 8 bit values are converted to their 14 bit value by applying the lookup table and stored in a signed 16 bit integer. The lookup table from the EDR labels contaings 256 pairs of 14 bit values. The first pair is the range of 14 bit pixels that were compressed to 8 bit pixel value zero (0). The second pair is the range compressed to pixel value one (1), and so on. 8 bit pixels are mapped to the corresponding average of the 14 bit lookup table range.

8 bit EDR pixel mapping and stats

Input DN	Output DN	Counter	Explanation
255 (0xFF)	NULL	Gap	Downlink data gaps are filled with 255s
254 (0xFE)	HIS	HIS	Sensor saturated on the high end
0 (0x00)	LIS	LIS	Sensor saturated on the low end

16 bit EDR pixels are checked for invalid values in the following order: gaps (-1 = 0xFFFF), low order byte appears to be the beginning of a gap (0x??FF), outside of unsigned 14 bit range (0 to 16383), high instrument saturation (16383 = 0x3FFF), and low instrument saturation (0 = 0x0000). Since the byte order of all HiRISE EDR products is most significant byte first all integer values within the EDR will be converted to the native byte order of the machine running "hi2isis" unless the cube attribute specifies otherwise.

16 bit EDR pixel mapping and stats

Input DN	Output DN	Counter	Explanation
-1 (65535) (0xFFFF)	NULL	Gap	Downlink data gaps are filled with 255s (0xFF)
(0x??FF) followed by (0xFFFF)	NULL (possibly)	Suspected	Beginning of a gap (see LSBGAP parameter)
0 < pixel > 16383	NULL	Invalid	The pixel is not in the unsigned 14 bit legal range
16383 (0x3FFF)	HIS	HIS	Sensor saturated on the high end
0 (0x00)	LIS	LIS	Sensor saturated on the low end

The line prefix and suffix data for the calibration and observation image are converted and stored into their respective tables in the same manner as the image pixels. The Isis tables which hold prefix and suffix data have four, four byte integer fields. These are "Gap Flag", "LineNumber", "BufferPixels", and "DarkPixels". The BufferPixel field contains twelve integers and the DarkPixel field contains sixteen integers. Other information from the EDR prefix tables such as the synchronization pattern are not transfered to the Isis file.

The "GapFlag" is taken directly from byte zero of the EDR line prefix data and is stored in the least significant byte of the four byte field integer. The upper three bytes are set to all zeros. The byte from the EDR has two possible values, all zeros and all ones. This means the Isis GapFlag value as an integer has two possible values, 255 and zero (0).

The "LineNumber" is taken from bytes three, four and five of the EDR line prefix data and is stored into a single four byte integer with the most significant byte set to zero.

The twelve values for "BufferPixels" are taken from the EDR line prefix buffer pixels. 8-bit buffer pixels are converted to 16 bit values in exactly the same way as image pixels. All buffer pixels are stored in the corresponding Isis "BufferPixels" array. All pixel values will be stored in the low order two bytes and will be swapped if the native byte order is least significant byte first.

The sixteen values for "DarkPixels" are taken from the EDR line suffix dark pixels, and are handled in the same manner as the buffer pixels.