This routine has been replaced with the GramSchmidtPanSharpening task.

This procedure performs Gram-Schmidt spectral sharpening, which sharpens a low spatial resolution multispectral image using associated high spatial resolution panchromatic bands. These two datasets are coregistered on the fly if they are both georeferenced. You can specify the low spatial resolution spectral band, or it can be determined from the low spatial resolution multispectral image.

Ensure that you have adequate disk space before performing a Gram-Schmidt transformation, because this process creates an output file and several temporary files. An error message will appear during the process if you do not have adequate disk space.

Syntax

ENVI_DOIT, 'ENVI_GS_SHARPEN_DOIT', DIMS=array, FID=file ID [, FILTER_FID=variable] [, FILTER_POS=array] [, HIRES_DIMS=array], HIRES_FID=file ID, HIRES_POS=array, /IN_MEMORY [, INTERP={0 | 1 | 2}] [, LORES_DIMS=array] [, LORES_FID=array] [, LORES_POS=array] [, M_FID=file ID] [, M_POS=array] [, MASK_VALUE=value], METHOD={0 | 1 | 2 | 3} [, OUT_BNAME=string array], OUT_NAME=string, POS=array [, R_FID=file ID]

Keywords

DIMS

The “dimensions” keyword is a five-element array of long integers that defines the spatial subset (of a file or array) to use for processing. Nearly every time you specify the keyword FID, you must also specify the spatial subset of the corresponding file (even if the entire file, with no spatial subsetting, is to be processed).

  • DIMS[0]: A pointer to an open ROI; use only in cases where ROIs define the spatial subset. Otherwise, set to -1L.
  • DIMS[1]: The starting sample number. The first x pixel is 0.
  • DIMS[2]: The ending sample number
  • DIMS[3]: The starting line number. The first y pixel is 0.
  • DIMS[4]: The ending line number

To process an entire file (with no spatial subsetting), define DIMS as shown in the following code example. This example assumes you have already opened a file using ENVI_SELECT or ENVI_PICKFILE:

  envi_file_query, fid, dims=dims

FID

The file ID (FID) is a long-integer scalar with a value greater than 0. An invalid FID has a value of -1. The FID is provided as a named variable by any routine used to open or select a file. Often, the FID is returned from the keyword R_FID in the ENVIRasterToFID routine. Files are processed by referring to their FIDs. If you work directly with the file in IDL, the FID is not equivalent to a logical unit number (LUN).

FILTER_FID (optional)

Use this keyword to specify a named variable representing the filter file ID to be used with METHOD=2 or 3. The filter file is in the form of a spectral library and contains the spectral response functions for the bands in a multispectral image. This file is only needed if the functions do not already exist in ENVI Classic.

FILTER_POS (optional)

Use this keyword to specify a scalar representing the index (position/location) of the filter function in the specified spectral library. If you do not specify a value for FILTER_POS, the default value is 0, and the first filter function in the library is used.

HIRES_DIMS (optional)

Use this keyword to specify the spatial dimensions of the high spatial resolution panchromatic band. HIRES_DIMS is a five-element array of long integers with the following definitions:

  • HIRES_DIMS[0]: A pointer to an open ROI; use only in cases where ROIs define the spatial subset. Otherwise, set to -1L.
  • HIRES_DIMS[1]: The starting sample number. The first x pixel is 0.
  • HIRES_DIMS[2]: The ending sample number
  • HIRES_DIMS[3]: The starting line number. The first y pixel is 0.
  • HIRES_DIMS[4]: The ending line number

HIRES_FID

Use this keyword to specify the file ID for the high spatial resolution panchromatic file. This value is returned from the keyword R_FID in the ENVI_OPEN_FILE procedure. FID is a long integer with a value greater than 0. An invalid file ID has a value of -1.

HIRES_POS

Use this keyword to specify the band position of the high spatial resolution panchromatic band. HIRES_POS is an array of long integers, ranging from 0 to the number of bands minus 1.

IN_MEMORY

Set this keyword to specify that output should be stored in memory. If you do not set IN_MEMORY, output will be stored on disk and you must specify OUT_NAME (see below).

INTERP (optional)

Set this keyword to one of the following values to specify the resampling method:

  • 0: Nearest neighbor
  • 1: Bilinear interpolation
  • 2: Cubic convolution

The low spatial resolution images are resampled to the high resolution space using the specified resampling method. The default method is nearest neighbor.

LORES_DIMS (optional)

Use this keyword to specify the spatial dimensions of the low spatial resolution spectral band. You must specify LORES_DIMS if METHOD=1. LORES_DIMS is a five-element array of long integers with the following definitions:

  • LORES_DIMS[0]: A pointer to an open ROI; use only in cases where ROIs define the spatial subset. Otherwise, set to -1L.
  • LORES_DIMS[1]: The starting sample number. The first x pixel is 0.
  • LORES_DIMS[2]: The ending sample number
  • LORES_DIMS[3]: The starting line number. The first y pixel is 0.
  • LORES_DIMS[4]: The ending line number

LORES_FID (optional)

Use this keyword to specify the file ID for the low spatial resolution multispectral file. You must specify LORES_FID if METHOD=1. This value is returned from the keyword R_FID in the ENVI_OPEN_FILE procedure. LORES_FID is a long integer with a value greater than 0. An invalid file ID has a value of -1.

LORES_POS (optional)

Use this keyword to specify the band position of the low spatial resolution spectral band. You must specify LORES_POS if METHOD=1. LORES_POS is an array of long integers, ranging from 0 to the number of bands-1.

M_FID (optional)

Use this keyword to specify the file ID of the mask file. This value is returned from the keyword R_FID in the ENVI_OPEN_FILE procedure. M_FID is a long integer with a value greater than 0. An invalid file ID has a value of -1.

M_POS (optional)

Use this keyword to specify the band position of the mask band. M_POS is a long integer with a value greater than or equal to 0.

MASK_VALUE (optional)

Use this keyword to specify the output value for the masked pixels. MASK_VALUE is only used when you specify M_FID and M_POS. The default value is 0.

METHOD

Use this keyword to specify the method for creating the low spatial resolution simulated panchromatic image. Set METHOD to one of the following values.

  • 0: Average all the bands specified by POS to simulate a low resolution simulated panchromatic image
  • 1: Use the low spatial resolution spectral band specified by LORES_FID, LORES_DIMS, and LORES_POS. The algorithm assumes that the low spatial resolution spectral bands correspond to the high spatial resolution panchromatic band.
  • 2: Create a low spatial resolution simulated panchromatic image using a high spatial resolution panchromatic filter function. If you specify this value, you must use the keyword F_FID. The low spatial resolution spectral bands must fall in the range of the high spatial resolution panchromatic band or they will not be included in the resampling process.
  • 3: Create a low spatial resolution simulated panchromatic image using a user-defined filter function. If you specify this value, you must use the F_FID keyword. The low spatial resolution spectral bands must fall in the range of the high spatial resolution panchromatic band or they will not be included in the resampling process.

OUT_BNAME (optional)

Use this keyword to specify a string array of output band names.

OUT_NAME

Use this keyword to specify a string with the output filename for the resulting data. If you set the keyword IN_MEMORY, you do not need to specify OUT_NAME.

POS

Use this keyword to specify an array of band positions, indicating the band numbers on which to perform the operation. This keyword indicates the spectral subset of bands to use in processing. POS is an array of long integers, ranging from 0 to the number of bands minus 1. Specify bands starting with zero (Band 1=0, Band 2=1, etc.) For example, to process only Bands 3 and 4 of a multi-band file, POS=[2, 3].

POS is typically used with individual files. The example code below illustrates the use of POS for a single file with four bands of data:

  pos=[0,1,2,3]
                  
envi_doit, 'envi_stats_doit', dims=dims, fid=fid, pos=pos, $
                  
comp_flag=3, dmin=dmin, dmax=dmax, mean=mean, stdv=stdv, hist=hist

But what if you need to create an output file consisting of data from different bands, each from different files? Library routines such as CF_DOIT and ENVI_LAYER_STACKING_DOIT can accomplish this, but they use the POS keyword differently. Suppose you have four files, test1, test2, test3, and test4, with corresponding FIDs of fid1, fid2, fid3, and fid4, respectively. In the following example, you want Band 3 from test1 in the first position, Band 2 from test2 in the second position, Band 6 from test3 in the third position, and Band 4 from test4 in the fourth position. The code should be as follows:

  fid_array = [fid1,fid2,fid3,fid4]
                  
pos=[2,1,5,3]
                  
envi_doit, 'cf_doit', dims=dims, fid=fid_array
                  
out_name='test_composite_file'

R_FID (optional)

ENVI Classic library routines that result in new images also have an R_FID, or “returned FID.” This is simply a named variable containing the file ID to access the processed data. Specifying this keyword saves you the step of opening the new file from disk.