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Date Posted: 07:13:35 07/24/00 Mon
Author: Michel
Subject: Re: Envision Library Oddities (but new user as well!)
In reply to: Chris Swinney 's message, "Envision Library Oddities (but new user as well!)" on 07:43:17 07/18/00 Tue

Dear Chris,

I apologies for the delay. I have been on vacation and was planning to continue working on

Envision, but I took the time off instead.

About the scanning, you should not run it from the IDE; I have had that problem before; I

think the twain message loop interferes with the IDE. Most scanners will return ifColor256

with gray scale images. A gray scale image is really a color image, where the palette

entries have the same R, G, and B values. The only way to know for sure is to look at the


For reading the TIFF file with JPEG compression, I'm not sure what the error you are

receiving is. The first possibility is that the exception is raised internally and handle by

the library itself. Does the TIFF file load properly with the compiled Demo.EXE program?

Best regards,


> Hi,
> I'm just putting together a simple archiving
> application using your Envison Library. I have come
> accross a few problems (I think) that I am unsure of
> how to solve.
> Firstly, when running the application (or demo) in the
> compiler and scanning, an External Exception error
> C0000008 is created when calling the CallTriplet
> function within the finnaly section of the
> TScanner.Acquire procedure. Everything seems fine when
> running the exe so I'm not sure how much of a problem
> this is, but I can't test multiple scans then in the
> compiler. This happens under NT and 2000, but haven't
> checked 98 (using HP ScanJet 5200C).
> Secondally, after a little bit of fiddling I managed
> to get the Scanned image to return a ifGray256 image
> as requested, by changing the Look up value in the
> GetImageFormat Procedure. Is there a better way of
> checking the exact pallet to determine whether a
> scanned image is GrayScale or Colour?
> Thirdly, after returning the Gray scale image, I can
> compress using tcJPEG, and if the image is multipage
> then write to a Tiff file using Jpeg compression.
> However, in the demo when trying to read a tiff file
> that uses JPEG compression, I recieve the error
> "Unsupported compression tag 6". I even manage to fool
> the thing into recogising this tag as Jpeg, but it
> falls of later on. At this point I gave up. The
> written file is fine, however, and can be read by
> other programs like Windows Imaging.
> Sorry if this goes on a bit, but I try to give you the
> fullest picture. Otherwise, this has been an
> invaluable purchase and I hope that the package keeps
> getting better.
> Once Again,
> Thanks,
> Chris.

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