This routine has been replaced with the Export method to ENVIRaster for the following formats: ENVI, NITF, and TIFF/GeoTIFF.

Use this procedure to output image data to external formats.

Syntax

ENVI_OUTPUT_TO_EXTERNAL_FORMAT [, /ARCVIEW] [, /ASCII] [, BLOCK_HEIGHT=long integer] [, BLOCK_WIDTH=long integer], DIMS=array [, /ENVI] [, /ERDAS] [, /ERMAPPER], FID=file ID [, FIELD=array] [, /IMAGINE] [, /JP2] [, /NITF] [, OUT_BNAME=string array], OUT_NAME=string [, /PCI], POS=array [, /TIFF]

Keywords

ARCVIEW (optional)

Set this keyword to specify output to ArcView format.

ASCII (optional)

Set this keyword to specify output to ASCII format. If you set this keyword, you must also specify the FIELD keyword.

BLOCK_HEIGHT (optional)

Use this keyword to specify a long integer representing the vertical size (in pixels) of the image block. This keyword is only valid when you set the IMAGINE keyword. Valid values are positive integers less than or equal to the image height. The default value is determined for each image, and is a block size (in pixels) optimized for writing from ENVI Classic.

BLOCK_WIDTH (optional)

Use this keyword to specify a long integer representing the horizontal size (in pixels) of the image block. This keyword is only valid when you set the IMAGINE keyword. Valid values are positive integers less than or equal to the image width. The default value is determined for each image, and is a block size (in pixels) optimized for writing from ENVI Classic.

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.

  • DIMS[0]: Unused for this routine; 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

ENVI (optional)

Set this keyword to specify output to ENVI Classic format. If you set this keyword, you may optionally specify band names using the keyword OUT_BNAME.

ERDAS (optional)

Set this keyword to specify output to an ERDAS .lan format.

ERMAPPER (optional)

Set this keyword to specify output to ER Mapper format.

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).

IMAGINE (optional)

Set this keyword to specify output to ERDAS IMAGINE 8.x format. Any character in the OUT_NAME string that is not valid for the ERDAS filename convention is changed to an underscore character (_) when you use this keyword.

JP2 (optional)

Set this keyword to specify output to JPEG2000 format.

FIELD (optional)

Use this keyword to specify a two-element array of long integers representing the ASCII character field width and precision, respectively. The first element of the array specifies the number of characters in the external field, and the second element specifies the number of positions after the decimal point.

NITF (optional)

Set this keyword to specify output to an NITF formatted file. To write multiple image segments, pass the FID array returned by ENVI_OPEN_DATA_FILE to ENVI_OUTPUT_TO_EXTERNAL_FORMAT. The NITF file will not be written if you pass only the FID for the composite image segment, if you pass an FID array containing FIDs from different image segments, or if you do not pass an array containing all FIDs for the file.

OUT_BNAME (optional)

Use this keyword to specify a string array of output band names. This keyword is valid only when used with the ENVI keyword (for ENVI output files).

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.

PCI (optional)

Set this keyword to specify output to PCI Geomatics format.

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'

TIFF (optional)

Set this keyword to specify output to TIFF format.

API Version

4.2