User's Guide

MULLI

Reverse the effects of illumination correction

Function:

Reverse the effects of illumination correction applied to an image during calibration. This capability is necessary because if a product was calibrated with illumination correction, it should not be later atmospherically corrected without first reversing the effects of illumination correction.

Parameters:

IN
Input image. A LAS image of containing AVHRR channel 1 and 2 data respectively. These bands must contain byte data and must be scaled using "US" scaling.

DATEBAND
Composite date band. The 'date band' generated during the creation of the composite. The band signifies which acquisition image each pixel in the composite came from. This image is expected to be the same size and in the same space as the composite specified by IN.

SCALE
Scaling technique used to generate the composite.


US     US scaling technique

DATELOG
Date log. The log file associated with the DATEBAND image which specifies the scenes used to generate the composite. See User Note 2 for more information.

PERIODS
Period name(s). The period names that were included in the composite. For example, '008014' for a US composite (julian days 008 through 014). NOTE: This parameter is not used if the date log file specified in DATELOG is a 'short' format file (all entries in the date log file are assumed to be within the period of interest).

OUT
Output image. Image containing AVHRR channel 1 and 2 data without the effects of illumination correction. This image will be the same size and in the same space as the composite specified by IN. This image will always contain BYTE data, with "US" scaling applied, and will always be compressed.

Examples:

  1. LAS> mulli in="[mydir.subdir]us_098(:1,2)" dateband="[mydir.subdir]us_098(:10)" scale="us" datelog="[mydir.subdir]us_098;log" periods="098104" out="[mydir.subdir]us_098out"

    The user has requested to process bands 1 and 2 of a composite (AVHRR channels 1 and 2). The date band for the composite resides in band 10 of 'us_098'. "US" scaling will be applied to the input and the output image. The date log file to be used is 'us_098;log' (see MULLIINFO for more information). The period to consider within 'us_098;log' is "098104".

Description/Algorithm:

The effect of illumination correction on calibration coefficients for optical bands can be expressed as follows:

C_with_illum = C_without_illum * d * d / cos z

where C_with_illum = the new Calibration coefficient with illumination correction C_without_illum = the old Calibration coefficient without illumination correction d = distance between the sun and the earth z = solar zenith angle

Consequently, to 'undo' the effects of illumination correction, the following equation needs to be applied:

C_without_illum = C_with_illum * cos z / (d * d)

Nonfatal Error Message:

  1. [mulli-warn] Nonfatal error encountered

    A nonfatal error was encountered during processing. The error message that is displayed immediately preceding this message is the specific error that was encountered. Processing will continue.

Fatal Error Messages:

  1. [mulli-fatal] Fatal error encountered

    A fatal error was encountered during processing. Processing is terminated. The error message that is displayed immediately preceding this message is the specific error that was encountered.

  2. [mulli-badbnd] Invalid number of input bands (<X>) specified

    An input image was not specified with the correct number of bands. Examine the input image specification and rerun.

  3. [mulli-badimg] Invalid number of input images (<X>) specified

    The number of input images was not specified correctly. Examine the input image specification and rerun.

  4. [mulli-alloc] Error allocating dynamic memory

    An error occurred while trying to allocate memory. Contact the system administrator if the error persists.

  5. [mulli-band] Invalid date band specification

    A date band mismatch has occurred. Ensure that the date band image and date band log file coincide and rerun.

  6. [mulli-type] Input image must contain BYTE data

    The input image specified must be BYTE data. Specify an image with BYTE data and rerun.

  7. [mulli-imgs] Invalid sized input image specified

    The number of lines and samples specified within the bands of IN and DATEBAND must be the consistent (same number of lines/samples in each band). Rerun with the correct IN and DATEBAND specification.

User Notes:

  1. Typically Global 1-KM AVHRR composites have been generated without applying illumination correction at the time of calibration. Consequently, MULLI does not need to be run on these composites. Typically US AVHRR composites have historically been generated with illumination correction applied at the time of calibration (thereby making MULLI a necessary software tool).

  2. The date band log file is generated at the time the composite is generated. For a sample input date band log file, see the file 'us_232245;log' ('long' format), or the file '1992p19;log' ('short' format) stored under CVS as part of the MULLIINFO module.