Message-Id: <200109042208.f84M87b02704@sitelicense.arizona.edu> Date: Tue, 4 Sep 2001 16:05:56 -0600 From: Tim Au Yeung <mailto:ytau@UCALGARY.CA> Subject: Re: unexpected end-of-file encountered To: mailto:IMAGELIB@LISTSERV.ARIZONA.EDU
<pre>
I've run into it many times -- the problem lies in the size of the files.
Usually this isn't a problem on smaller files but with large files, you can
encounter a buffer overrun or underrun that isn't properly reported in the
CD writing software -- it looks like it's written properly but it hasn't.
The solution is usually to set the speed of the writer to a slower speed.
Also try creating disk image prior to writing to the CD-R. However, always
stay at 2x and above; I've seen some lit. suggesting that the current CD-Rs
don't write well at 1x. As well, there's the typical suggestions for
improving CD-writing performance such as not running anything in the
background like antivirus during the write, defragmenting the hard drive,
not writing across a network, etc.
Another problem is in bad bits; if the bad bits aren't that substantial,
Photoshop can sometimes recover but large portions of bad bits can cause a
file to go south.
A technique I use to ensure good CD writes is to generate a CRC-32 value for
images prior to writing to CD; once written I generate a CRC value on the
files on CD -- a quick comparison of the two shows if the write is
successful. It's worked like a charm; I once did a write that had a couple
files with wildly different CRCs. I opened up the CD and the hard drive
versions and they both looked fine at first gloss. After a fair bit of
searching, I was able to identify 6 pixels that had dropped out due to bad
bits.
Also Photoshop is very finicky about properly written file formats; if you
do need to try to recover a corrupted file, try one of the file conversion
utilities. I've generally had better luck with things like Irfan View and
the like than Photoshop.
Tim
--------------------------------
Tim Au Yeung
Manager, Digitization Initiatives
Information Resources (Press)
University of Calgary
voice: (403) 220-8975
e-mail: ytau (at) ucalgary.ca
----- Original Message -----
From: "Guenter Waibel" <mailto:guenter@UCLINK4.BERKELEY.EDU>
To: <mailto:IMAGELIB@LISTSERV.ARIZONA.EDU>
Sent: Tuesday, September 04, 2001 3:31 PM
Subject: Re: unexpected end-of-file encountered
>
> Hi Julie & all,
>
> yes, I have run into this problem before, and posted to various lists
> (including this one), and unfortunately, nothing turned up. Then I
> e-mailed Bruce Fraser, (co-)author of the Real World Photoshop series
> and general digital imaging guru. He essentially said that once that
> error occurs, there's nothing that can be done unless you want to
> engage in some extremely time-consuming excavation of the hex code
> itself. At that point, I wrote off the files, gave up the quest. I
> still get e-mail from folks who find my old posts and are looking for
> a solution to this exact same problem themselves.
>
> All of this to say: you're not alone, Julie (if that's any
> consolation), but this error is bad news, and the files to my best
> knowledge are beyond resurrection. I'd love it if somebody could
> prove me wrong on this one, but after all the fruitless digging and
> posting, I doubt it.
>
> I've lost about 120 low-res image files sitting on a server to this
> error, and 2 high-res 100 MB tiff files. The circumstance which
> trigger the error are still unclear, which actually is what bothers
> me the most. The files were easily refreshed from back-up, but I'd
> like to be able to prevent the problem from occurring in the first
> place. I guess the story just re-inforces the same old lesson: make
> more than one back-up.
>
> best,
> Guenter
>
>
> At 1:14 PM -0500 9/4/01, Julie Dees wrote:
> >I have run into a problem with some PC-format, RGB TIFFs I have been
> >trying to back up to CD-ROM using Adaptec's Easy CD Creator 4.05. Ten of
> >the thirteen images copy fine and can be opened in Photoshop 5.5 (the
> >same program I used to create and save the original images) with no
> >trouble. Three images can't be opened from the CD and give me an
> >"unexpected end-of-file encountered" error message. I can open the hard
> >drive and server copies of these three TIFFs with no trouble, but the
> >three times I have tried to copy the thirteen images to CD I have
> >received the same error message on the same three images. What could be
> >causing the problem? Has anyone run into this before?
> >
> >Many thanks in advance for your assistance,
> >Julie Dees
> >Archival Reformatting Unit
> >Mississippi Department of Archives and History
>
> --
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
> Guenter Waibel
> Berkeley Art Museum & Pacific Film Archive
> Digital Media Developer http://www.bampfa.berkeley.edu/
> Digital Imaging SIG Chair, MCN http://www.mcn.edu/visig_subscribe.taf
> mailto:guenter@uclink4.berkeley.edu
> Phone 510-643-8655
> Fax 510-642-4889
> ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>
</pre>
This archive was generated by hypermail 2b29 : Tue Sep 04 2001 - 17:23:36 CDT