photom Documentation

photom - Apply photometric correction

The "photom" program applies the file created by PHOTOMPR which defines
the photometric transformation from input brightness to output
brightness to the input image.  PHOTOM uses the simple gray level
interpolation scheme known as nearest neighbor interpolation.  The input
file can be in any geometric projection.  If OPTION = PHOTOM, the
following correction will be performed:
	     OUTPUT BRIGHTNESS = INPUT BRIGHTNESS * A + B

If OPTION = ALBEDO, an additional albedo-dependent phase angle
correction, which varies with the value of each input DN is performed.
You must run PHOTOMPR with FUNC = MOONPR prior to running PHOTOM and
choosing the ALBEDO option.  The final output value when the ALBEDO
option is chosen is the reflectance at incidence and phase angles of
30 degrees and emission angle of 0 degrees.  The parameters D, E, F,
G2, XMUL, WL, H, BSH1, XB1, and XB2 are used only if OPTION = ALBEDO.
The program will enter a default value for each of these parameters
if the planet is the "moon" and the user leaves the paramter blank.
The lunar defaults are as follows:
  D = 0.14
  E = -0.3575 * WL - 0.0607 if WL is less than 1.0; otherwise -0.4179
  F = 0.55
  G2 = -0.9585 * WL + 0.98 if WL is less than 1.0; otherwise 0.02
  XMUL = 1.0
  WL = will be read from the cube label
  H = 0.048
  BSH1 = 19.89 - 59.58 * WL + 59.86 * WL**2 - 20.09 * WL**3
  XB1 = -0.0817
  XB2 = 0.0081

If OPTION = NOALBEDO, the following correction will be performed:
	     OUTPUT BRIGHTNESS = INPUT BRIGHTNESS * A

The user should enter the same SFROM value as was used for PHOTOMPR.
There is no check for the same SROM value, however your results
may not be what you expect if a different SFROM is used for the
two programs.

PROGRAMMER: Jim Mathews

Input cube file name
 (Default extension is .cub)

NONE

 Input subcube specifier

--

Output cube file name
 (Default extension is .cub)

NONE

Transformation file
 (No default file extension)

sun.dat

Choose a program option
  PHOTOM, ALBEDO, or NOALBEDO

PHOTOM

Empirically derived coefficient
  Used only with OPTION=ALBEDO

--

Empirically derived coefficient
  Used only with OPTION=ALBEDO

--

Empirically derived coefficient
  Used only with OPTION=ALBEDO

--

Empirically derived coefficient
  Used only with OPTION=ALBEDO

--

Used to convert radiance to
  reflectance or apply
  calibration fudge factor
  Used only with OPTION=ALBEDO

--

Wavelength in micrometers
  Used only with OPTION=ALBEDO

--

Empirically derived coefficient
  Used only with OPTION=ALBEDO

--

Empirically derived coefficient
  Used only with OPTION=ALBEDO

--

Empirically derived coefficient
  Used only with OPTION=ALBEDO

--

Empirically derived coefficient
  Used only with OPTION=ALBEDO

--

Output pixel type
    0 = input type
    1 = 8 bit
    2 = 16 bit
    3 = 32 bit

0

Output min/max data range

0,1

ADDITIONAL NOTES:

Parm	Description
FROM	Input cube file name. If the file extension is omitted, then ".cub" will be assumed.
SFROM	SFROM specifies the subcube using a single string for all three dimensions of the cube. The order of the three dimensions is always "samples:lines:bands". If a dimension is left blank, all the data for that dimension is selected. The default value of NULL for SFROM selects the entire cube. Any application below can be used for any dimension. To select specific data from any dimension: "10-100(3):11,12,15-20:1-10(2)" = This example will select every third sample starting with sample 10 thru 100. It selects lines 11 and 12, and 15-20. It selects every other band, starting with band 1 thru 10. There are special characters that can be used for selecting a subcube efficiently, such as "*","#", and "~". For examples type "help sfrom" in TAE. **NOTE** For more examples and explanation of the many features of the SFROM parameter, tutor the sfrom.pdf or refer to Introduction To ISIS, Section 6, of the ISIS User's Manual **
TO	Output cube file name. If the file extension is omitted, then ".cub" will be assumed.
TFILE	Name of the Transformation file
OPTION	Choose the option the program will use. PHOTOM will perform the photometric correction. ALBEDO will perform the photometric correction plus an albedo-dependent phase angle correction. NOALBEDO will perform the correction without applying the additive value B. For more information see the general help above.
D	Empirically derived coefficient
E	Empirically derived coefficient
F	Empirically derived coefficient
G2	Empirically derived coefficient
XMUL	Used to convert radiance to reflectance or apply calibration fudge factor.
WL	Wavelength in micrometers
H	Empirically derived coefficient
BSH1	Empirically derived coefficient
XB1	Empirically derived coefficient
XB2	Empirically derived coefficient
OTYPE	Output pixel data type. Permitted values are: 0 = output type is same as input file pixel type 1 = 8-bit (integer with type conversion parameters) 2 = 16-bit (integer with type conversion parameters) 3 = 32-bit (floating point) When processed data are being written back into the input file, the output pixel type must be the same as the existing pixel type in the input file.
ORANGE	Output pixel data range. If ORANGE is (0,0), then the CORE_BASE and CORE_MULTIPLIER in the output file will be set to represent the same range of data as the input file. If OTYPE=1 (8-bit) or OTYPE=2 (16-bit), then the CORE_BASE and CORE_MULTIPLIER in the output file will be set to values that allow representing the specified range of output values. Output values outside this range will be stored as a special "representation saturation" value. The ORANGE parameter is ignored if OTYPE=3 (32-bit) since the CORE_BASE and CORE_MULTIPLIER are not applicable to floating point pixel values. **NOTE** For a more detailed explanation of ORANGE, tutor the orange.pdf.