Hi Chris,
Your example script is great. It worked very well for me and it's
fast. My tiff is 11520x5760 px and your method works in less than a
minute, which is much faster than the other method I was using to
convert the ASCII to the tiff with ArcMap, which took about an hour
and a half. Pnmtotiff complains that it can't find a 'magic number'
(the error is : " Error reading magic number from Netpbm image
stream." ) but the image comes out fine.
Thanks a lot !
Janos
On Dec 15, 2007 8:24 AM, Chris Marshall <[EMAIL PROTECTED]> wrote:
> I submitted a fix to PDL CVS yesterday that appears to work for
> 16-bit PNM and PNG file types. That should be available in the
> next PDL release. Thanks again for the report.
>
> In the meantime, you could either build from the CVS sources if
> you are comfortable with that. Otherwise, you could hand roll a
> 16-bit grayscale PNM image that could be converted by another
> utility like pnmtotiff or arcmap...
>
> Here is the sequence from the perldl shell:
>
> use PDL;
> use PDL::NiceSlice;
> use PDL::IO::Pic;
> use PDL::IO::FlexRaw;
>
> $a = sequence(256,255)->ushort;
>
> $fh = new IO::File "> test.pnm";
>
> print $fh "P5\n";
> print $fh join(' ', $a->dims) . "\n";
> print $fh "65535\n";
>
> $hdr = writeflex($fh, $a(:,-1:0));
>
> $fh->close;
>
> system('pnmtotiff test.pnm >test.tif');
>
> Hope this helps. --Chris
>
>
> János Gonzales wrote:
> > Just to close up this topic, I wasn't able to create 16-bit Tiffs from
> > PDL but I was able to print out the piddle into an ASCII file, and
> > then used another program (Arcmap) to transform that to a 16-bit
> > raster.
> >
> >
> >
> > On Dec 12, 2007 2:38 PM, Christian Soeller <[EMAIL PROTECTED]> wrote:
> >
> >> 24 bit RGB is really 3 separate 8-bit channels which does not help you.
> >> Whenever I need to preserve data with higher bit depth I use the netcdf
> >> interface (PDL::NetCDF) which is a CPAN module.
> >> Christian
> >>
> >>
> >>
> >> On 13/12/2007, at 8:41 AM, János Gonzales wrote:
> >>
> >> Hi Christian,
> >>
> >> Thanks so much for your response. Maybe I'm missing something here,
> >> but I don't understand how all the Pic code is in 8 bit, since on the
> >> PDL homepage they have an example where they transform a JPEG image of
> >> a space shuttle which is a 24 bit image. They use 'wim' to export and
> >> I thought that was a Pic subroutine. I don't necessarily have to
> >> output a TIFF, just any image format that will hold all of my values
> >> above 255. Do I have another option?
> >>
> >> Janos
> >>
> >>
> >>
> >>
> >> On Dec 12, 2007 12:14 PM, Christian Soeller <[EMAIL PROTECTED]>
> >> wrote:
> >> Hi Janos,
> >>
> >> The currently included Tiff IO code (and all other Pic code) is 8 bit only.
> >> A better interface would use libtiff for I/O but that is non-trivial due to
> >> the variety of TIFFs one encounters in the field.
> >>
> >> I once made a very simplistic 16bit TiFF reader for PDL. Somebody
> >> sufficiently knowledgeable could write a 16bit writer I suppose.
> >>
> >> Christian
> >>
> >>
> >>
> >>
> >>
> >> On 13/12/2007, at 6:34 AM, János Gonzales wrote:
> >>
> >> Hello,
> >> This is probably really easy, but I'm a newbie so I'm not sure how to
> >> do it. I'm trying to output a 16-bit Tiff, but all I get is an 8 bit
> >> tiff.
> >> Here's my pseudo code:
> >>
> >>
> >> use PDL;
> >> use PDL::NiceSlice;
> >> use PDL::IO::Pic;
> >>
> >> $blank_slate = zeroes(1800,900);
> >>
> >> .......in here i add values to the blank_slate piddle from 0 to about 3000
> >>
> >> $blank_slate->wpic("test.tif");
> >>
> >>
> >> So, if I look at test.tiff it's 1800x900 pixels, but the max value is
> >> 255 and not 3000. If it was a 16-bit tiff it could accomodate this
> >> value. I'm running this on Windows XP, and I have the netpbm binaries
> >> installed. (I noticed my wpic command calls pnmtotiff )
> >>
> >> Any ideas?
> >>
> >> Thanks much,
> >> Janos
> >>
> >> _______________________________________________
> >> Perldl mailing list
> >> [email protected]
> >> http://mailman.jach.hawaii.edu/mailman/listinfo/perldl
> >>
> >> --
> >> Christian Soeller PhD Dept. of Physiology +64 9 3737599 x82770
> >> University of Auckland Auckland, New Zealand fax +64 9 3737499
> >>
> >>
> >>
> >>
> >>
> >> --
> >> Christian Soeller PhD Dept. of Physiology +64 9 3737599 x82770
> >> University of Auckland Auckland, New Zealand fax +64 9 3737499
> >>
> >>
> >>
> >
> > _______________________________________________
> > Perldl mailing list
> > [email protected]
> > http://mailman.jach.hawaii.edu/mailman/listinfo/perldl
> >
> >
> >
>
>
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