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Image Processing Methods
Procedures in selection, registration, normalization and enhancement of satellite imagery in coastal wetlands

1.1.1 Season
1.1.2 Water Level
1.1.3 Cloud cover
1.1.4 Simultaneous coverage
1.1.5 Specifications
1.2.1 Download raw imagery
1.2.2 Check header file
1.2.3 Visual check
1.2.4 Line replacement
and destriping
1.3.1 Coordinate System
1.3.2 Ground control in image
1.3.3 Ground control in field
1.3.4 Create model
1.3.5 Satellite image
1.3.6 Accuracy check
1.4.1 Radiometric correction
1.4.2 Atmospheric correction
1.4.3 Aerosol correction
1.5.1 Vegetation Index
1.5.2 Wetness Index
1.5.3 Temperature
1.5.4 Water Reflectance
2.2.2 GCPREP
2.2.3 SMODEL
2.2.4 CIM2 - New file
2.2.5 GEOSET - georeference
2.2.6 SORTHO - satellite image
2.2.7 Inter-scene accuracy check
2.3.1 TMRAD
2.3.2 RAYRAD -
Rayleigh radiance
2.3.3 Dark object
2.4.1 Bitmap creation
2.4.2 Vegetation Index
2.4.3 Wetness Index
2.4.4 Thermal band 6
2.4.5 Water reflectance
2.4.6 Brightness
Image Pre-Processing Outline
Sample Header File
Data Storage
Chapter 2
Image processing software procedures


Many of the image pre-processing steps are conducted within an image-processing software package. The Center for Coastal Geology group uses PCI, Inc. The following chapter includes specific instructions on running the procedures. It should serve as a guide to the basic steps required within this program.

Initial scene selection and ordering is conducted outside of the image processing package. A flow chart (Plate 4) is provided to help the novice follow the different kinds of steps involved and the order in which they are conducted. The check list in Appendix A should become the basis for your own notes, including adjustments and new developments.


Imagery is downloaded from the CD-ROM disk with CDNLAPS or CDEOSAT, depending on the format of the disk. Important information is included in the header file. Take time to learn to read the header file with the instructions accompanying your order. Look for format (NLAPS or EOSAT), band sequential or pixel interleaved (BSQ, BIL), number of pixels and lines, date and time of acquisition, resampling scheme (NN, CC, BL), and so on.

Once downloaded to a .pix file, examine each band at full resolution for missing lines or blocks of missing data, heavy clouds, and the histogram of dn values. Each band should exhibit a normal range and distribution for the season and region covered. Now is the time to repair or return an image with serious problems.

Table 3 shows the parameters set for CDNLAPS. Table 4 shows parameters set for LRP to fix line number 100 in band 2 with the mean from the line above and the line below. The EASI procedure, LRP, requires the operator to specify the missing line(s) +1 to correctly identify the lines to be replaced. If destriping is attempted, read about DSTRIPE in EASI help.


The orbital segment created in CDEOSAT or CDNLAPS contains information used in an adjustment between the estimated latitude/longitude of the raw imagery and the desired coordinate system. SMODEL creates a model from the orbital segment and a ground control point segment. The ground control segment is created in GCPWORKS.


Imagery for the Florida Wetlands is rectified with ground control collected with GPS units and is reprojected to the UTM coordinate system. Ground control selection is described in Chapter 1, and can be conducted in any image display program, including PCI's IMAGEWORKS. Once the ground control has been identified and field collected, run GCPWORKS to enter the coordinates at their respective locations in the image. The satellite orthorectification option is selected to permit the use of the orbital segment in the model.

Select "Collect/review GCPs only", "Satellite Ortho Correction", "User Entered Coordinates", and then "Select Uncorrected Image". Enter the path and filename of the nlaps.pix file. Load three bands, usually natural color (3,2,1) or false color (4,3,2) are preferred for display. Set the units to meter, and the coordinate system to UTM, zone 17, row R and ellipsoid WGS84. Obviously, the zone and row will change depending on the region. Identify the location of 8 to 12 ground control points and enter the corresponding UTM coordinates collected with the GPS unit.

During the identification of ground control within GCPWORKS, watch the RMS error for each ground control point and the total RMS in both x and y. Within reason, it is possible to adjust the location of the ground control in the imagery to achieve optimal positioning and distortion-free rectification.

In GCPWORKS it is possible to also enter accuracy check points at this time. If not working in this program, these check points are set aside for a post-rectification accuracy check. The 10-12 accuracy check points must be of equally high quality and well-distributed about the scene. Care is given to treat these positions and the associated error objectively, as they eventually provide a measure of the model's accuracy. These positions should be entered at the end, when the ground control points have been securely identified to avoid adjusting the model to fit the check points. When the operator is satisfied with the location of the ground control and the total RMS error, the ground control point segment is saved within GCPWORKS. Ideally, this will be segment #3.

Table 3. CDNLAPS procedure parameters
CDEOSAT CD EOSAT Fast Format                    V6.0 EASI/PACE  12:31 16-Feb-97
NLAPSHD - NLAPS Header File Name          :/cdrom/cdrom1/filename.hd
FILE    - Database File Name              :path/newfile.pix
CDIC    - CD Input Channel List           }        1        2        3        4        5        6        7   
TEX1    - Database Descriptive Text 1     :path_row_location
REPORT  - Report Mode: TERM/OFF/filename  :path/newfileorb.rep

Table 4. LRP, line replacement parameters
LRP     Image Line Replacement                  V6.0 EASI/PACE  08:29 17-Feb-97 
FILE    - Database File Name              :pathname/filenlaps.pix
DBOC    - Database Output Channel List    }        2
DBOW    - Database Output Window          >      101
RMOD    - Replacement Mode: ABOV/BELO/MEAN:MEAN
LINC    - Line Increment Factor           >        1

2.2.2 GCPREP

A report documenting the ground control point segment as collected is obtained by running GCPREP. This produces a text file showing the list of ground control points, their pixel/line locations, the user-entered coordinates, and errors. The UTM coordinates of the ground control is exactly what was entered within GCPWORKS. This will change when the model is run in SMODEL. Remember, in GCPWORKS, the satellite orthorectification was selected. This forces the orbital segment to be referenced while developing the model. GCPREP does not refer to the orbital segment, and thus does not reflect it's influence on the ground control. The output from another procedure, GCPWRIT, may be useful in creating a vector segment. It requires a little editing and then running VREAD. The vector may be displayed in subsequent displays to help relocate the ground control points for new imagery.

2.2.3. SMODEL

SMODEL draws on both the orbital segment and the ground control point segment to create the model, and must always be run on the whole scene. It is ineffective to run on a partial scene. If check points were entered along with the ground control, SMODEL will also produce a table showing the accuracy of the check points in meters. Run SMODEL as shown in Table 5. Both the orbital segment, 2, and the ground control point segment, 3, must be specified in the procedure. SMODEL produces a model segment, normally 4, which will be applied in the image rectification, SORTHO.

SMODEL also produces a report showing the accuracy of the check points in meters. Examine the report for values outside of the range of expected and desired accuracy (see Appendix C). Excessive values below the original 10 m accuracy of the GPS positions may introduce distortion to the final image rectification. Values greater than 20 m, or 2/3 pixel, suggest the overall registration may not meet inter-scene registration requirements. Note also that the UTM coordinates shift by the RMS error.

Values for positional accuracy in this project are acceptable between 8-20 m. The rectification of a TM scene will technically meet 1:25,000 map accuracy standards, provided that 90% or more of the individual accuracy check points are within 20 m or less of their desired location. With 12 check points, only one can be 20 m from its true location. Although we achieve the reported level of map accuracy, TM imagery will always be printed at scales of 1:50,000 or smaller to avoid the blocky appearance of the pixels.

Table 5. SMODEL procedure parameters
SMODEL  Satellite Model Calculation             V6.0 EASI/PACE  10:57 19-Feb-97
FILE    - Database File Name              :path/newfile.pix
DBGC    - Database Ground Control Segment >        3
ORBIT   - Orbit Segment Number            >        2
MODEL   - Satellite Model Segment         >
MODINPUT- Modify Input                    :NO
ELLIPS  - Ellipsoid for the Earth         :E012
ERRUNIT - Error Unit: Pixel/Metre         :METRE
REPORT  - Report Mode: TERM/OFF/filename  :path/smodel.rep

2.2.4 CIM2 - New file creation

New imagery files are created in CIM2, a file format which creates a separate file for each band, all associated by the header or .pix file (Table 6). The size of a fully-processed full size Landsat TM scene makes this option appealing for ease of movement and disk-space issues. The example shows the standard size of the north Big Bend image, path 18, row 39. The size includes the removal of ~1100 lines in the state of Georgia and the enlargement of the file to reproject the region into the UTM coordinate system (see Figure 3). All north scenes will be created in the same manner. If working in another region, establish a standard file size based on the full extent of the UTM eastings and northings and the pixel size.

Table 6. Creation of new file for rectification in CIM2
CIM2    Create Database and Image Channel Files V6.0 EASI/PACE  14:14 16-Feb-97
FILE    - Database File Name              :path/newortfile.pix
TEX1    - Database Descriptive Text 1     :p18r39
TEX2    - Database Descriptive Text 2     :sortho file/northern Big Bend
DBSZ    - Database Size: Pixels, Lines    >     7556     5412
PXSZ    - Pixel Ground-Size in Metres     >       28.5       28.5
DBNC    - No. of Channels: 8U,16S,16U,32R >        7

2.2.5 GEOSET - georeference segment

Every file in PCI has a georeferencing segment created automatically as segment 1.

The geographic boundaries, the UTM zone, and the ellipsoid are set for the georeferencing segment of the newly created CIM2 file with GEOSET. An example for the north Big Bend is shown in Table 7. The coordinates given are applied to each corresponding image, making overlays and inter- scene analysis a simple task.

Table 7. Georeferencing segment set with GEOSET procedure in PCI
GEOSET  Set Georeferencing Segment              V6.0 EASI/PACE  14:10 19-Feb-97
FILE    - Database File Name              :path/newortfile.pix
UPLEFT  - Upper Left Position for Database>  3317100   201900
LORIGHT - Lower Right Position for Databas>  3085020   447000
MAPUNITS- Map Units: PIXEL/UTM/others     :UTM 17 R E012

2.2.6 SORTHO - satellite image orthorectification

Orthorectification of imagery is conducted in PCI with the SORTHO procedure which applies the model segment to the nlaps image file and reprojects the seven bands of data into the empty bands of the newly created and georeferenced .pix file. See Table 8 for SORTHO parameters.

Due to the minimal topographic variation along the Big Bend coast of Florida, we do not employ a DEM file. Instead, we estimate an average value for elevation as the width of one pixel with no offset (ESCALE). Elevations do not exceed ~60 m in the area, and this appears to be sufficient for positional accuracy and inter-scene registration. The need for elevation must be determined on a region-by- region basis. The SORTHO procedure may take up to 6 hours on a SUN SPARC 20 and is usually run overnight.

Table 8. Parameters for satellite orthorectification procedure
SORTHO  Satellite Image Orthorecification       V6.0 EASI/PACE  14:22 16-Feb-97
FILI    - Database Input File Name        :path/nlapsfile.pix
FILO    - Database Output File Name       :path/newortfile.pix
FILEDEM - Database DEM File Name          :
DBIC    - Database Input Channel List     }        1        2        3        4        5        6        7
DBOC    - Database Output Channel List    }        1        2        3        4        5        6        7
DBEC    - Database Elevation Channel List >
BACKELEV- Background Elevation Value      >
ESCALE  - Elevation Scale and Offset      >     28.5        0
DBIW    - Database Input Window           >
MODEL   - Satellite Model Segment         >        4
PXSZOUT - Output Pixel Ground-Size        >     28.5     28.5

2.2.7 Inter-scene accuracy check

The inter-scene registration accuracy check is conducted manually within an image display program. Run IMAGEWORKS with a full-resolution window ~600 x 800 with 6 image planes. Display 3-5 well-distributed regions in the window, each time loading the newly registered image (4,3,2) and the base image (4,3,2) with the same input window.

For instance, in image planes 1,2,3 load the new image (4,3,2) with an input window of 300, 300 (x,y offsets), 600, 800 (x,y window size). Then load the base image to image planes 4,5,6 (4,3,2) using the same full-resolution window. Examine the images first with a single band from each of the images in a RGB display mode. An example may be viewed in Plate 3. Look for truly horizontal or vertical roads and evaluate obvious offsets. A poorly registered image as shown to the left in Plate 3 is not worth evaluating further. Note the direction of the offsets, check other regions to confirm the offsets, and return to GCPWORKS to redo the ground control point segment.

If horizontal and vertical roads align well in the first input window, switch to a flicker state with each image displayed 4,3,2 as RGB. Select 3-5 right-angle road intersections for evaluation. See Plate 2 for selection of road intersections. Flicker to the base image and zoom in on a selected intersection. Place the cursor at the center of the intersection, drawing two imaginary lines N/S and E/W to determine the exact location. Leaving the cursor in position, flicker to the newly registered image. Again, mentally draw two lines and determine the exact center of the new intersection. Do not move the cursor. Evaluate if the cursor is exactly on target, off by 0.5 pixel, 1.0 pixel, or > 1.0 pixel in both the x and y directions. See Plate 1 for evaluation of cursor location.

Complete a table as follows, with 12-20 road intersections across the scene. The table will highlight regional or full-scene offsets. If all regions, and the whole scene meet expectations of ± one pixel inter-scene alignment, then the new file is acceptable, and image processing proceeds. If, however, a region or the whole scene exceeds one pixel offset in either direction, then GCPWORKS, SMODEL and SORTHO must be repeated. The table may be used to help guide the adjustment of the ground control points.

For example in a TM scene:
Region   x offset (pixel)   y-offset (pixel)
NW 1		0 		0.5 -
NW 2		0.5 +		0.5 -
NW 3		1.0 +		0.5 -
NE 1		0		0.5 -
NE 2		0.5 +		0
NE 3		0.5 +		0.5 -
SE 1		0.5 +		1.0 -
SE 2		0.5 +		0
SE 3		0		0.5 -
SW 1		0.5 +		0.5 +
SW 2		0.5 +		0.5 +
SW 3		0.5 +		0.5 +


The following sections illustrate the EASI procedures used for radiometric calibration and atmospheric correction. Information from the header file is employed in the procedures. A bitmap is created first to mask the non-image pixels of the *ort.pix file. Typically the mask can be obtained by selecting all pixels in band 1 or band 2 with values greater than zero. The mask is subsequently used for the creation of indices and other analysis. Limiting the processing to the image area of the file shortens processing time and eliminates the formation of anomalous features outside of the image area. The EASI thresholding procedure, THR may be used for creating the bitmap (Table 9). If necessary a similar mask may be created for the non-image area by setting the COMP parameter to "ON". The complement is used to fix anomalous data sometimes found in band 6.

Table 9. Bitmap creation with THR
THR     Thresholding Image to Bitmap            V6.0 EASI/PACE  09:34 17-Feb-97
FILE    - Database File Name              :fltms/fileort.pix
DBIC    - Database Input Channel List     }        1
DBOB    - Database Output Bitmap          }
TVAL    - Threshold Value (Min,Max)       >        1      255
COMP    - Complement: ON/OFF              :OFF
DBSN    - Database Segment Name           :imageon
DBSD    - Database Segment Descriptor     :image bitmap excluding non-image border

2.3.1 TMRAD

Seven additional empty channels are added using PCIADD2. These are the output channels for the radiometrically enhanced bands, 8-14. TMRAD is an in-house EASI procedure which solves equations 1 and 2 in section 1.4.1. Sample parameters are set in Table 10. Latitude and longitude are given in decimal degrees, and longitude is a negative value in the western hemisphere. TMSLOPE and TMBIAS may be obtained from the newer header files as Gain/10 and Bias/10, respectively. The solar constants (from Markham and Barker, 1986) and scale factors will change for different imagery and satellites. TEXT may be set to "stat" for a check on the output values Table 11, which is also saved to a text file for reference.

Table 10. EASI procedure TMRAD
TMRAD - radiometric correction of TM imagery    V5.3 EASI/PACE  09:10 15-Aug-95
FILE    - Database File Name              :/imagery/tm95/TM19950402
DBIC    - Database Input Channel List     >      1      2      3      4      5      6      7   
DBOC    - Database Output Channel List    >      8      9     10     11      12     13     14
DATESITE   -,  GMT,  lat, long (W < 0) >       92     1511  28.8686 -82.4237
TMSLOPE - Slope for TM or MSS band        >   0.0632   0.1254   0.0964   0.0907
                                              0.0125   0.0055   0.0067
TMBIAS  - TM or MSS offsets for channels 1>   -0.118  -0.1935  -0.1697  -0.1628
                                             -0.0248   0.1238  -0.0125
TMSOLAR - TM or MSS solar constants 1 - 7 >    195.7    182.9    155.7    104.7
                                               21.93        1    7.452
SCALEF  - Scale factor for units to counts>    500    500    500    500    500    100    
TEXT    - Text input                      :seg

Table 11. TMRAD output
Julian Day (year-day)=       92
             Time (GMT)           =     1511
             Lat/long             =  28.8686  -82.4237
***          Solar zenith angle   =   40.5686  degrees  ***
***          Solar azimuth angle  =  119.377   degrees  ***
***          Earth-sun distance   =   0.999353  a.u.    ***
cos(sza) = 0.759628
band #        1         10.00133387
    slope    bias    solar  irradiance  refl/ct
  0.0632   -0.118    195.7     148.852   0.00133387
band #        2         20.00283185
    slope    bias    solar  irradiance  refl/ct
  0.1254  -0.1935    182.9     139.116   0.00283185
band #        3         30.00255726
    slope    bias    solar  irradiance  refl/ct
  0.0964  -0.1697    155.7     118.427   0.00255726
band #        4         40.00357806
    slope    bias    solar  irradiance  refl/ct
  0.0907  -0.1628    104.7      79.636   0.00357806
band #        5         50.00235428
    slope    bias    solar  irradiance  refl/ct
  0.0125  -0.0248    21.93     16.6802   0.00235428
band #        6         6  0.0055
    slope    bias    solar  irradiance  refl/ct
  0.0055   0.1238        1    0.760612     0.0055
band #        7         70.00371355
    slope    bias    solar  irradiance  refl/ct
  0.0067  -0.0125    7.452     5.66808   0.00371355

2.3.2 RAYRAD - Rayleigh radiance

The Rayleigh correction factor is calculated with RAYRAD. Calculations may be found in Stumpf (1992). The procedure requires operator input as in Table 12, and produces output as in Table 13. The scale factor should be the same as that used in TMRAD.

Bands 1 - 4 are corrected by subtracting the Rayleigh values from each band respectively. The Rayleigh values are the last column in Table 13, rounded to the nearest whole number. Values for bands 5 and 7 are insignificant, and for band 6, irrelevant. The model used to accomplish the subtraction is shown in Table 14. The bitmap is specified with "%%2" and band 8 as "%8". Keep in mind that the radiometrically enhanced bands, 8 - 14, are equivalent to TM bands 1 - 7.

Table 12. RAYRAD input
/pci/usgs/bin: rayrad
 enter latitude (decimal degrees)
 enter longitude (decimal degrees, where west < 0)
 enter time in GMT, (hhmm)
 enter Julian day
 enter scalefactor (conversion of reflectance to counts for processed imagery)

Table 13. RAYRAD output
channel  radiance    reflectance    counts
1      3.5128        0.0571        28.5
2      1.6372        0.0285        14.2
3      0.7739        0.0158         7.9
4      0.1991        0.0060         3.0
5      0.0026        0.0004         0.2

solar constants       tau r          tau g
196.0             0.17110         0.01
183.0             0.08920         0.03
156.0             0.04840         0.02
105.0             0.01850         0.02
21.7             0.00110         0.00
solar declination =    14.686262184445
solar zenith angle =    31.398820329709
solar azimuth =    113.20862349932

Table 14. Rayleigh subtraction model
doc     *************************************************************
doc     Correction of the radiance values gathered from using the
doc     rayrad program.  This program will allow corrections of the
doc     digital numbers for bands 1 through 7
doc     *************************************************************
monitor = "ON"
report = "TERM"

file = "/path/fileort.pix"
see file
MODEL ON  file
35      if (%%2 = 1) %8 = %8-29
rem 36  print "29 subtracted from dn for band 1"
40      if (%%2 = 1) %9 = %9-14
rem 41  print "14 subtracted from dn for band 2"
45      if (%%2 = 1) %10 = %10-8
rem 46  print " 8 subtracted from dn for band 3"
50      if (%%2 = 1) %11 = %11-3
rem 51  print " 3 subtracted from dn for band 4"
55      if (%%2 = 1) %12 = %12
rem 56  print " 0 subtracted from dn for band 5"
60      if (%%2 = 1) %13 = %13
rem 61  print " 0 subtracted from dn for band 6"
65      if (%%2 = 1) %14 = %14
rem 66  print " 0 subtracted from dn for band 7"
100 return

2.3.3 Dark object subtraction

Table 15.
Darkwater values:
Channel 1: 16
Channel 2: 12
Channel 3: 8
Channel 4: 6
Final atmospheric correction values are selected manually from a full-resolution display of bands 1 - 4, focused on areas of dark water. The subtraction itself can be conducted with EASI procedure, ARI, or with a model similar to
Table 14. The values shown in Table 15 are in the normal range for the region of the Big Bend coast. All channel descriptors (image layer histories) are renamed using MCD to more accurately describe the contents of the channel based on the pre-processing applied.


Several indices are calculated at the final point in processing. An additional band is added to the .pix file for each index desired. Be sure to specify the correct band number when calculating an index. The examples below are based on the radiometrically enhanced data residing in bands 1-7. It is possible to protect previously processed image channels from accidental overwrites with the LOCK procedure.

2.4.1 Bitmap creation

A mask is employed to permit processing and modeling of image-only pixels. . The mask is created by selecting all pixels with a value of > 0 in TM band 1 or 2. The new bitmap segment is on at every image pixel and off at all non-image pixels. It is important that the operator check the band at full-resolution to ensure there are no zero values in the image area itself before running this procedure. The results can be checked afterwards on full-resolution display. Failure to check may result in missing data in the index channels. The mask is created by running THR as in Table 9. The mask allows the operator to run processes on image data only, maintaining values of zero in non-image areas of the file.

2.4.2 Vegetation Index

The vegetation index, NDVI may be calculated in the EASI procedure, RTR (Table 16). Alternatively, a model can be written to take the input channels 3 and 4 and write output NDVI to channel 8. Differences in NDVI between two years may range from ~-90 to +90. These values are re-scaled to range from 1 - 200.

%8 = 100 * (%4 - %3) / (%4 + %3)

2.4.3 Wetness Index

The wetness index may be calculated with EASI procedure, ARI (Table 17). It may also be run as an EASI model:

%9 = %5 - %2

2.4.4 Thermal band 6 temperature

Temperature is calculated from TM thermal band 6 (Markham and Barker, 1986) to degrees Celcius plus 5. We add 5 degrees to adjust for close to freezing temperatures which may occasionally occur in the Big Bend region. The model is run from a file as follows:

MODEL ON "/pathname/filename.pix
if %%2 = 1  %10 = 

where segment 2 is a bitmap, masking image- only pixels.

2.4.5 Water reflectance

Water reflectance can be calculated with EASI procedure, ARI, (Table 18) or as follows:

%11 = %2 - %4

2.4.6 Brightness

Brightness is merely TM band 2 with the appropriate adjustments for radiometric enhancement and atmospheric corrections. This is sufficient for comparison of brightness between scenes.

Table 16. Calculation of NDVI using EASI RTR
RTR     Real Database Channel Ratioing          V6.0 EASI/PACE  14:54 16-Feb-97
FILE    - Database File Name              :path/fileort.pix
CNUM    - Channels for Ratio Numerator    }       4       3
WNUM    - Weights for Ratio Numerator     >        1       -1
NCON    - Constant for Ratio Numerator    >        0
CDEN    - Channels for Ratio Denominator  }       4       3
WDEN    - Weights for Ratio Denominator   >     0.01     0.01
DCON    - Constant for Ratio Denominator  >        0
DBOC    - Database Output Channel List    >       8
SMOD    - Scaling Mode: NONE/AUTO/LOGS    :NONE
MASK    - Area Mask (Window or Bitmap)    >        2
ZERODIV - Value for Division by Zero      >      255

Table 17. Calculation of the wetness index with EASI ARI
ARI     Image Channel Arithmetic                V6.0 EASI/PACE  14:34 16-Feb-97
FILE    - Database File Name              :path/fileort.pix
CNST    - Input Scalar                    >        0
MASK    - Area Mask (Window or Bitmap)    >        2
DBIC    - Database Input Channel List     }       5      2
DBOC    - Database Output Channel List    >       9
ZERODIV - Value for Division by Zero      >      255
AUTO    - Autoscaling mode: ON/OFF/USER   :OFF
RVAL    - Function Min,Max, Output Min,Max>

Table 18. Calculation of water reflectance with EASI ARI procedure.
ARI     Image Channel Arithmetic                V6.0 EASI/PACE  14:34 16-Feb-97
FILE    - Database File Name              :path/fileort.pix
CNST    - Input Scalar                    >        0
MASK    - Area Mask (Window or Bitmap)    >        2
DBIC    - Database Input Channel List     }        2       4
DBOC    - Database Output Channel List    >       11
ZERODIV - Value for Division by Zero      >      255
AUTO    - Autoscaling mode: ON/OFF/USER   :OFF
RVAL    - Function Min,Max, Output Min,Max>

Coastal and Marine Program > St. Petersburg Coastal and Marine Science Center > Research by Theme > Gulf of Mexico Tidal Wetlands > Image Processing Methods - OFR 97-287 > Chapter 2

U.S. Department of the Interior, U.S. Geological Survey, St. Petersburg Coastal and Marine Science Center
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Updated January 04, 2013 @ 10:28 AM (THF)