>To all
>A new problem appeared this week which is disconcerting.
>We have a Biorad MRC-1000 and use Confocal Assistant 3.10 to
>convert biorad .pic files to .tif files so that they can be used for
>image manipulation on other computers. In the past few days some of
>the converted .tif files will not open in Photoshop on  Macs (at
>least 5 different Macs have been tried). The error message is -
>"Could not open [file name] because an unexpected end-of-file was
>encountered. -39" Not all files that are in the batches have this
>problem, some do and some do not. Those that do not open on the Macs
>open fine on the Biorad PC computer. Also none of my PC users have
>this problem. If you try to convert the files a second time it
>sometimes works, but usually does not.  If you look at the sizes of
>the files that open vs. those that do not, the ones that do not open
>are 10-20% smaller than the ones that do open. Since Zip disks are
>the exchange and storage medium, we tried different Zip disks to no
>avail. It seems that if some tag is missing on the files that do not
>open, is there a fragmentation problem, is it a MacLink problem.
>Any suggestions would be appreciated.


You need to look more closely at the problem.  Are all the images the
same size in pixels?  CAS doesn't use compression when it writes TIFF
files so all should come out the same size.  If some files are coming
out short then an error is occurring - either in the writing or the
transfer.  A flaky disk, bad link or whatever.  Since you give no clue
how the images are getting to macs and PCs (what links are common and
what are different?) its hard to know at this distance.

What software will and will not open the images?  A TIFF file (like
almost any other image file) tells the software what size the image
should be.  But what a piece of software will do with a truncated
file will vary.  A quick look suggests that a CAS TIFF file has its
header information all at the front so all is not lost if the file
is truncated.  Therefore a program can either do the best it can and
display as much of the image is there or give up and say (correctly)
that the image is incomplete.

Are the images still different sizes on the PC that WILL open them?
If so, the bottom of the picture should be blank or rubbish (maybe
this is off the screen, though).

I've assumed throughout that the original images were all one size.
If this is not so, and the images which won't open are supposed to
be smaller (Biorad pics can be any size) there are other possibilities.
Some versions of Thruview generated files which were one pixel shorter
than the original image (which means they were odd numbers and therefore
would not fit into integers) and some software seriously disliked
images with such dimensions.

You are welcome to email me (not the list!!!) copies of the offending
images and I'll see if I can spot what's wrong.

                                                Guy Cox

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