🚀 go-pugleaf

I just found comp.lang.postscript which seems like it might be a better
group to post this on.  So I've posted it there as well.

John.

"John Stewart" <john.stewart@_RE_MOVE_tentechnologies.com> wrote in message
news:eF_8c.44596$Oo5.41524@twister.nyroc.rr.com...
> I'm using the image operator with a dictionary to render TIFF files
resident
> on disk.  For /DataSource I use a file (created by opening the TIFF file
and
> setting the file position to the start of the data) and the appropriate
> filter based on the TIFF compression type.  This is all working great.
>
> I'm now working on a striped TIFF file where the data is saved as multiple
> strips in the TIFF file.  It's easily processed by reading the TIFF header
> to determine the number of strips, bytes per strip and the strip offsets.
>
> My problem is that I need to modify my /DataSource from a single filtered
> file to a procedure that processes all of the strips of data.  My current
> /DataSource looks something like this for an LZW file where f1 is the
input
> TIFF file with it's file position set to start of the data:
>
> /DataSource f1 /LZWDecode filter
>
> So for my striped file all I get from this is the first strip of data
> rendered (the strip appears to have an EOD at the end so everything
buttons
> up nicely).  I can see how to render the whole image by calling image once
> for each strip and translating between each call.  But it seems like I
> should also be able to modify my /DataSource to return all (n) strips of
the
> file.  This has the advantage that my supporting code would be no
different
> regardless of the type of file processed.
>
> And this is where I lose it.  I'm having trouble understanding the Data
> Source construction enough to write a procedure which will do this.  All I
> need to do is, for each strip,  <f1 StripOffset setfileposition f1
> /LZWDecode filter> and repeat for each strip.  But I can't figure out how
to
> do this as part of the /DataSource of the image dictionary.
>
> Does anybody have an examples of a /DataSource that does anything like
this
> or have any comments about my problem?
>
> Thanks in advance for any input.
>
> John Stewart
> Ten Technologies.
>
>