USGS MIPS Wtcmbo Documentation

USGS MIPS Wtcmbo Documentation

This program is used to generate the sum of multiple images using different weights and offsets for each image. The following equation is used to calculate the output DNs :

Out = (In1 - O1) * C1 + 
      (In2 - O2) * C2 +
          .
          .
          .
          .
      (In7 - O7) * C7 +
       ADDBACK

Where,

In(i)   is the ith input image
O(i)    is the ith offset
C(i)    is the ith multiplicative coefficient
ADDBACK is an overall output additive constant

The offsets, multiplicative coefficients, and addback values which are specified by the user can be any real number. Therefore, by using negative values for selected multiplicative coefficients subtration operations can be applied(i.e., create a difference image), or the average of a set of images can be generated by using values less than one.

Files

This program uses as input a one to seven unsigned 8-bit , signed 16-bit , or 32-bit floating point image files; all input files must be of the same data type. It generates one output image file that has the same data type as the input images. The following label information is transferred from the first input file to the output file(if appropriate):

Image labels
Mosaic labels
Projection labels
Sonar labels
Navigation file
History file

Parameters

C and O: These parameters are arrays for setting the multiplicative coefficients and offsets for each input image. For example, if four input images are being used then each array would have four elements: C1-C4 and O1-O4. The default value for multiplicative coefficients is 1 and for offsets is 0.
ADDBACK: This parameter is an overall additive constant for the output results, with default values of zero. It is generally used to keep the output dn values in the proper range for the given bit type(e.g., 0 to 255 for unsigned 8-bit images). For example, if either the sum of several 8-bit images exceeds 255 the user can subtract a constant or if the difference of two 8-bit images generates negative values, -200 and +127 could be used, respectively.

Uses

For example, to create the difference of two images the following parameters can be used:

C1 = 1, C2 = -1, O1 = 0, O2 = 0, ADDBCK = 127

Note, integer values can be used or real numbers such as 1.0 or 0.75. The difference image will be centered about 127 and major differences will have dn values above and below the 127 mid-range/no-difference dn value.

Examples

From left to right, Landsat TM Band 3, Landsat TM Band 4, and the difference image generated using C=(1,-1) and ADDBACK=127.

[Example Image]

From left to right, Landsat TM Band 3, Landsat TM Band 4, and the sum image generated using C=(1,1) and ADDBACK=0.

[Example Image]

From left to right, Landsat TM Band 3, Landsat TM Band 4, Landsat TM Band 5, and the average image generated using C=(.333,.333,.333) and ADDBCK=0.

[Example Image]