Data Set Overview : This data set contains products acquired by the MAHLI instrument.  This data set uses the Committee on Data Management and Computation (CODMAC) data level numbering system. The MSL MAHLI EDRs are considered Level 2 or Edited Data (equivalent to NASA Level 0). The EDRs are reconstructed from Level 1 or Raw Data. Processing : After receipt on Earth, processing at JPL begins with the reconstruction of packetized telemetry data (raw telemetry packet SFDU's with CFDP headers) into depacketized binary data products and associated Earth metadata files. MMMEDRGEN combines the Earth metadata with additional data extracted from the binary data files to create an EDR with the corresponding label. (SFDU - Standard Formatted Data Unit; CCSDS - Consultative Committee for Space Data Systems; CFDP - CCSDS File Delivery Protocol) Data :  The EDRs produced contain raw, uncalibrated data and have detached PDS-compliant labels. The Mast Camera (Mastcam), Mars Hand Lens Imager (MAHLI), and Mars Descent Imager (MARDI) Experiment Data Record (EDR) and Reduced Data Record (RDR) PDS Data Products Software Interface Specification contains a detailed description of the EDR formatted products. There are 8 video data types (5 images, 3 thumbnails) that can be wrapped into the original data format that is transferred from the cameras. Some of these are compressed in a format which can reproduce an image identical to the original image on the instrument (lossless compression), some are transferred in lossy format, some are full-scale and others sub-sampled (the only sub-sampled is by a factor of 8, used to produce thumbnail images). The EDR data file includes the camera mini-header generated by the camera, followed by original image data as formatted by the camera. Not including sub-framing, MAHLI can take a variety of image data formats and accomplish this by internal processing. The cameras always acquire raw 12-bit data. Normally, the 12-bit raw data are converted from 12-to-8-bits through the use of a variety of companding (compress/expand) lookup tables, the most generally used being a modified square-root encoding scheme that allocates additional values to low DNs. These companded, 8-bit images can then be processed either immediately, and stored into each camera's 8-Gbyte buffer, or they can be stored unprocessed in the buffer, and then later processed in response to downlink commands. It is this flexibility that leads to the complexities of the raw data format and its description. In addition to the 12-to-8-bit companding, on-board processing includes the following capabilities: Bayer pattern interpolation, lossless compression, and JPEG compression. Except for thumbnails, the cameras do not support sub-sampling or resampling, but do support sub-framing. Thumbnails are produced by creating a scratch JPEG image, and extracting the lowest order coefficients of the discrete cosine transform 8x8 pixel compression block, or minimum compression unit (MCU), which is essentially the average of the 8x8 spatial domain MCU. These coefficients are then assembled into a smaller image which is then JPEG compressed. The extraction of these coefficients is the only way MAHLI images are ever sub-sampled. The following is a table of the different video product types generated by MAHLI which are contained within the raw camera data record.  Type Product Format Pixel bits ------------------------------------------- J Video Raster 8 K Video Lossless 8 L Video JPEG gray 8 M Video JPEG 422 24 N Video JPEG 444 24 O Thumbnail Raster 8 P Thumbnail JPEG gray 8 Q Thumbnail JPEG 444 24 Refer to the Mast Camera (Mastcam), Mars Hand Lens Imager (MAHLI), and Mars Descent Imager (MARDI) Experiment Data Record (EDR) and Reduced Data Record (RDR) PDS Data Products Software Interface Specification for further details on the MAHLI data products.

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