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Re: envi_setup_head for TIFF [message #56153 is a reply to message #56152]

Fri, 05 October 2007 11:33

Leonardo R. Sbaraini is currently offline

Leonardo R. Sbaraini
Messages: 26
Registered: October 2007

Junior Member

Jeff, I tried ENVI_OPEN_FILE plus ENVI_FILE_QUERY but it did no
reuturn the header size that is my goal.
By other way, I had success in reading some labels using the IFD
offset in the header (field #3), but after byte 8 (after header) the
data was supposed to be there....I read one single value (float) and
it returned a value different from that ought to be.

Well let me explain better:
TIFF Header :

Byte Order | TIFF Identificator | IFD Offset
(2bytes) (2bytes) = 42 (4 bytes)

Normally the image values will be the next data.

; ************************************
; Piece of code to read a single value
; ************************************
point_lun, fu, 8
readu, fu, data
print, 'data:', data

IDL prints:
1.2748951e-310

Real value in SRF file created before: 0.000000

This TIFF was generated by Envi Menu (Save as..)

The reason to read by this way (using point_lun) is that I have big
huge images here that cannot be stored in a IDL variable, so I cannot
use READ_TIFF. And other reason is that I need to output rect pieces
into file.

Any help is welcome.

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[Message index]

		Re: envi_setup_head for TIFF By: Leonardo R. Sbaraini on Fri, 05 October 2007 12:45
		Re: envi_setup_head for TIFF By: Jean H. on Fri, 05 October 2007 11:54
		Re: envi_setup_head for TIFF By: Leonardo R. Sbaraini on Fri, 05 October 2007 11:33
		Re: envi_setup_head for TIFF By: Jeff N. on Fri, 05 October 2007 07:30

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