gllssical

This program is used to radiometrically correct flight images using a linear model of the light-transfer function. This program is specific to the Galileo SSI camera. References: 1) D-4264 MIPL Software Structural Design for the Instrument Calibration of GLL SSI Science Processing. 2) K. Klaasen, "Reduction in Number of Unique SSI Calibration Files", 29 May 1987. 3) 625-210,"Galileo SSI Calibration Report Part 1", K. Klaasen, H. Breneman, November 1, 1988. This program will radiometrically correct the input image, converting the input DN values to some specified radiometric unit. The program requires a radiometric file generated from calibration data acquired at the same filter position as the input image, and a dark-current file acquired at the same camera gain-state, frame-rate, PNI, and BPM settings. Also, extended exposure mode frames require an extended-exposure mode dark-current file. This program extracts the filter position, exposure time, and frame-rate from the label of the input file to determine the required gain file to use. The file $ISIS3DATA/galileo/calibration/gll_gain.sav defines the gain file to use for the given filter, gain state, and frame mode. The file $ISIS3DATA/galileo/calibration/gll_dc.sav defines the DC file to use for the given, gain state, frame mode, frame rate, blemish protection mode, clock mode, and extended exposure mode. This program performs the following processing steps on each pixel: 1. The radiometric correction is applied: e = z(d - dc) where z is retrieved from the Radiometric File and dc is retrieved from the Dark-Current File. 2. The output pixel is scaled to radiometric units R. S1 K r = e * -------- * --- (D/5.2)**2 A1(t-to) Ko where S1 = filter-dependent conversion factor from ft-Lamberts to I/F units for a reference distance of 5.2 AU from the Sun. t = commanded exposure time of the input image (msec). to = line-dependent shutter offset. K = system gain constant for the gain-state of the image. Ko = system gain constant for the calibration file gain-state. D = target distance from the Sun (in AU). 5. The output DN is usually in the range of 0.0 to 1.0. If the uneven bit weighting correction is enabled, the input DN values (d) will be corrected for uneven-bit-weighting due to the ADC. If the input dark-current file is in byte format (i.e. an individual dark-current frame), then the correction will be applied to the dark-current as well. The current correction table was supplied by Herb Breneman, 2 Mar 89, and is based on 1975 calibration data.