Data Set Overview : This data set contains products acquired by the Mastcam  instruments. There are two cameras in this set with 34  and 100 mm focal lengths referred to as MAST_LEFT and  MAST_RIGHT, respectively. This data set uses the Committee on Data Management and Computation (CODMAC) data level numbering system. The MSL Mastcam RDRs are considered Level 4 or Resampled. The RDRs are created from EDR images and contain irreversibly transformed data due to the nature of JPEG decompression. Processing : After extracting and decompressing (if needed) EDR products, 2 RDR products are created for each EDR. These are generated from validated data. The products are: (1) decompressed and radiometrically calibrated (16-bit), (2) decompressed, radiometrically calibrated, and color corrected (8-bit). Data  : The RDRs produced 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 RDR formatted products. There are 2 zstack data types (1 image, 1 thumbnail) 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 RDR 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, Mastcam 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. Focus merge images are always JPEG 444 color images based on the 2 to 8 source images. 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 Mastcam images are ever sub-sampled. The following is a table of the different zstack product types generated by Mastcam which are contained within the raw camera data record.  Type Product Format Pixel bits ----------------------------------------------------- R Focus Merge Image JPEG 444 48 T Focus Merge Thumbnail JPEG 444 48 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 Mastcam data products and RDR processing.

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