MEX VMC Experiment Data Record (EDR)

EDR – Experiment Data Record

Instrument: Visual Monitoring Camera

PDS Data Set ID (Nominal Mission): MEX-M-VMC-2-EDR-V1

PDS Data Set ID (Extended Mission 1): MEX-M-VMC-2-EDR-EXT1-V1

PDS Data Set ID (Extended Mission 2): MEX-M-VMC-2-EDR-EXT2-V1

PDS Data Set ID (Extended Mission 3): MEX-M-VMC-2-EDR-EXT3-V1

PDS Data Set ID (Extended Mission 4): MEX-M-VMC-2-EDR-EXT4-V1

PDS Data Set ID (Extended Mission 5): MEX-M-VMC-2-EDR-EXT5-V1

PDS Data Set ID (Extended Mission 6): MEX-M-VMC-2-EDR-EXT6-V1

PDS Data Set ID (Extended Mission 7): MEX-M-VMC-2-EDR-EXT7-V1

DOI: Mars Express DOI Overview Page

For more information about VMC EDR products, see the VMC Product EAICD.

The VMC Archive EDR data products are in .RAW image format. The original data has the information of each physical pixel in a byte stream corresponding to the color filter on top of it following the Bayer pattern. The archived raw files are codified as unsigned integers with 8 bits, which means that their values range from 0 to 255. The pixels are read row by row, starting in the top left corner of the image and finishing in the bottom right corner. In some rare cases, there are missing bytes at the end of the file, and these are drawn as black. The file size is 640 x 480 bytes, corresponding to 307200 bytes, or 300 KB.

The browse products are provided for quick-look purposes in PNG format, which is a direct conversion of the raw product into an image with the Bayer pattern solved (see [VMC-DB]). Each PNG pixel has information for Red, Green and Blue. In order to keep the scientific fidelity, the way the images are processed is that each pixel keeps its original value for the corresponding Bayer grid colour and interpolated values are calculated by averaging the available adjacent pixels of the target original color (either 2 or 4 pixels).

In the Debayering process (see [VMC-DB]), each pixel keeps its original value for the corresponding colour on the Bayer filter grid, and for the other colour channels, the value is interpolated from the surrounding pixels. On the diagram in the final column, the colored squares (red, green and blue) represents an original colour value, and the grey colour represents an interpolated value for that colour channel. This means that:

  • Red in green pixels is interpolated from only 2 available adjacent red pixels.

  • Red in blue pixels from up to 4 pixels.

  • Green in red pixels from up to 4 pixels.

  • Green in blue pixels from up to 4 pixels

  • Blue in red pixels, from up to 4 pixels.

  • Blue in green pixels, from 1 or 2 pixels.

Note that this interpolation algorithm has limitations at the borders, in particular in the 2 pixel margin around each image, which should be handled carefully and taken into account for the scientific interpretation of the images.

VMC EDR products have the following file names:

VMC_TE_YYMMDD_hhmmss_ccc.RAW

where:

VMC – Visual Monitoring Camera

T – Purpose of data. S stands for Science.

E – Experiment Data Records (raw data)

YY – Year

MM – Month

DD – Day

hh – hours

mm – minutes

ss – seconds

ccc – counter of the image within an observation series

In ODE, EDR products have the following Product IDs:

VMC_TE_YYMMDD_HHMMSS_CCC.RAW

More information can be found in:

  • [VMC-DB] RE-VMC-0050-OIP/07. MEX-VMC Debayering Raw Images and Conversion to RGB images. OIP Sensor Systems. Issue 1. 2007