[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Re: Another IDL twist

edward.s.meinel@aero.org wrote:

> Does anyone know the rhyme or reason for the calling methods for the
> built-in IDL READ_* procedures? Sometimes it is:

I don't know why, but I do know it drove me bananas.  I wrote the
following as a wrapper for most of the READ_* procedures. It is in the
form of a FUNCTION rather than PROCEDURE.  I've only tried it on TIFF,
JPEG and GIF so far.  If you try and have suggestions, please send them



; ReadImage
; This function returns the 2 or 3 plane image specified by the file
; The utility of this function is that the user doesn't need to remember
; image reading procedures are actually fumctions.  The user can
; query the image only, or return the query structure and the image.
The _extra
; keyword is applied each of the apllicable image input procedures that
have keywords.
; Input/Output
; Result = ReadImage()
; All inputs are optional keywords.  If file is not specified the user
is prompted to selected one
; File: A string specifying the location of the image.  If not provided,
the user
;  is prompted to select a file.
; Query:  Set this keyword to a named vaiable that, on output, will
contain the info
;  structure retruned from the QUERY_IMAGE fucntion.
; JustQuery:  Set this keyword to a non zero scalar to simply return the
Query structure.
;  In this case, Image is returned as -1.
; Red, Green ,Blue:  Set these keywords to named variables that, on
output, contain
;  the red, green and blue color vectors stored with the image.   If the
;  has no color vectors stored these values are undefined.
; ColorTable:  Set this keyword to a named varaible that, on output
contains the
;  the 3,n color table array.  This feature is available for JPEG images
only.  If the image
;  have a defined colortable stored, this value is undefined.
; _Extra:  This keyword allows the user to set any of the many different
;  for each image type. See documentation fpor each image type for
;  that can be passed.
; Cancel: This keyword is set to 1 if the user cancels the
dialog_pickfile prompted, it is set to
;  0 (zero) otherwise.
; The ReadImage function returns the image specified by the file
keyword.  If the JUSTQUERY
; keyword is set, the user cancels the Dialog_PickFIle prompted, or an
error occurs then
; the fucntion returns -1.
; None.
; None known.
; Requires the function ParseFileName.
; The following returns the image 'c:/images/image.tif', the red, green,
and blue
; color tables associated with the image (if any.)  Also returned are
the GeoTiff structure
; (if the image is GeoTiff format) and the Info Structure returned by
; function QUERY_TIFF.
; Result = ReadImage( File='c:/images/image.tif', Red = Red, Green =
Green, Blue = Blue,$
;  Query= Query, GeoTiff = GeoTiff)
;  Written by: Ben Tupper  26 SEP 99
; Pemaqid River Company
; email pemaquidriver@tidewater.net
; tel:  (207) 563 - 1048
;   248 Lower Round Pond Road
; POB 106
; Bristol, ME 04539-0106

FUNCTION ReadImage, File=File, $
 Query = Query, _Extra = _Extra, $
 Red=Red, Green = Green, Blue = Blue, ColorTable = ColorTable,$
 JustQuery = JustQuery, cancel = cancel

Image = -1
Query = -1
Cancel = 1

If n_elements(JustQuery) EQ 0 Then JustQuery = 0
if n_elements(File) EQ 0 Then File = Dialog_PickFile()

if File EQ '' Then Begin
 Return, Image

FileName = StrLowCase(ParseFileName(File[0]))

Extension = FileName[2]

Case Extension of

 'bmp':  Result = Query_BMP(File, Query)
 'dcm':  Result = Query_DICOM(File, Query)
 'gif':  Result = Query_GIF(FIle, Query)
 'jpg':  Result = Query_JPEG(File,Query)
 'pic': Result = Query_PICT(FIle, Query)
 'png': Result = Query_PNG(FIle, Query)
 'ppm': Result = Query_PPM(File,Query)
 'pgm':  Result = Query_PPM(File,Query)
 'srf': Result = Query_SRF(File, Query)
 'tif':  Result = Query_TIFF(File,Query)


If Result EQ 0 Then Return, Image

Cancel = 0

If (JustQuery NE 0) Then Begin
 Return, Image

Case Extension of

 'bmp':  Image = Read_BMP(File, Red, Green, Blue,Ihdr,_Extra = _Extra)
 'dcm':  Image = Read_DICOM(File, Red,Green,Blue, _Extra=_Extra)
 'gif':  Read_GIF,FIle, Image, Red,Green,Blue, _Extra=_Extra
 'jpg':  Read_JPEG,File,Image, ColorTable, _Extra=_Extra
 'pic': Read_PICT, FIle, Image, Red, Green, Blue
 'png': Image = Read_PNG(FIle, Red, Green, Blue, _Extra=_Extra)
 'ppm': Read_PPM, File,Image, _Extra=_Extra
 'pgm':  Read_PPM, File,Image, _Extra=_Extra
 'srf': Read_SRF, File, Image, Red, Green, Blue
 'tif':  Image  = Read_TIFF(File,Red, Green, Blue, _Extra=_Extra)


Cancel = 0

Return, Image


Ben Tupper
Pemaquid River Company
248 Lower Round Pond Road
POB 106
Bristol, ME 04539

Tel: (207) 563-1048
Email: PemaquidRiver@tidewater.net