Use this procedure to perform HSV and color-normalized sharpening on an image.


This example performs color-normalized sharpening on an image.

; Start ENVI
e = ENVI()
; Open a high-resolution panchromatic image
File1 = Filepath('qb_boulder_pan', Root_Dir = e.Root_Dir, $
   Subdir = ['data'])
HighResRaster = e.OpenRaster(File1)
; Return a file ID for the high-resolution raster
HRFid = ENVIRasterToFID(HighResRaster)
; Query the high-resolution image
ENVI_File_Query, HRFid, DIMS=Hdims
; Open a low-resolution multi-band image
File2 = Filepath('qb_boulder_msi', Root_Dir = e.Root_Dir, $
   Subdir = ['data'])
LowResRaster = e.OpenRaster(File2)
; Return a file ID for the low-resolution raster
LRFid = ENVIRasterToFID(LowResRaster)
; Query the low-resolution image
ENVI_File_Query, LRFid, DIMS=Ldims
; Determine an output file
OutFile = e.GetTemporaryFilename()
; Perform color-normalized sharpening
ENVI_Doit, 'Sharpen_Doit', $
   FID = [LRFid, LRFid, LRFid], $
   F_FID = HRFid, $
   F_DIMS = Hdims, $
   F_POS = [0], $
   POS = [0,1,2], $
   METHOD = 1, $
   INTERP = 0, $
   OUT_NAME = OutFile, $
   OUT_BNAME = ['Red', 'Green', 'Blue']


ENVI_DOIT, 'SHARPEN_DOIT', F_DIMS=array, F_FID=file ID, F_POS=long integer, FID=file ID, /IN_MEMORY, INTERP={0 | 1 | 2}, METHOD={0 | 1}, OUT_BNAME=string array, OUT_NAME=string, POS=array, R_FID=variable



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

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


Use this keyword to specify the high resolution data file ID for the open 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.


Use this keyword to specify the band position of the high resolution sharpening band. F_POS is a single long-integer value greater than or equal to 0.


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).


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).


Use this keyword to specify an integer value corresponding to the interpolation type. Choose one of the following.

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


Use this keyword to specify the sharpening method. METHOD is one of the following long-integer values.

  • 0: HSV sharpening
  • 1: Color-normalized sharpening


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


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.


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:

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]
envi_doit, 'cf_doit', dims=dims, fid=fid_array


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.

API Version