Re: [NTG-context] error when using externalfigure

26 Nov 2012

      This seems to me a case of garbage in, garbage out; I'd say it's the
script's job, rather than ConTeXt's, to ensure the images have the
correct dpi to get a reasonable width in inches. (Brr. I hate inches.
Disgusting, Mars-mission-wrecking way of measuring things.)

Here is some pseudocode. You'd still need a way to get
image.width_in_pixels and image.dpi from the image; I daresay either
`convert` or `exiftool` can do the job. See also this recent mail to
the list by Guy Stalnaker:
http://archive.contextgarden.net/message/20121123.232556.bf205641.en.html

projected_width = image.width_in_pixels / image.dpi
if projected_width > max_width_in_inches then
   required_dpi = image.width_in_pixels / max_width_in_inches
   shell('convert --density %f %s', required_dpi, image_name)
end

Cheers,
Sietse

On Mon, Nov 26, 2012 at 1:32 PM, Hans Hagen  wrote:
...
On 11/26/2012 11:00 AM, luigi scarso wrote:
...
On Mon, Nov 26, 2012 at 10:50 AM, Hans Hagen  wrote:
...
On 11/26/2012 10:36 AM, luigi scarso wrote:
...
On Mon, Nov 26, 2012 at 10:20 AM, Pavel Dohnal 
wrote:
...
Hello,
I have a big context source file which contains pictures from different
sources. The problem is, that there are some pictures the context
cannot
process. It displays an error message and ends. I run the context from
another script in batchmode. After finishing, the context creates a PDF
file, which contains this problematic picture but the pdf is broken. It
does
not have numbers in the table of contents and it is not arranged by
setup.
Here is a minimal example:
\starttext
\externalfigure[http://cdn-locations-images.tripomatic.com/img-poi1295-5ZTynx-s.jpg][width=26.5mm]
\stoptext
when I save the jpg  as eps from gimp
I see
width = 6096,00
height=4064,00
The first value is off for TeX.
if i print the values from the img object i get
17344.8pt
11563.2pt
so the problem is deep down in the jpg reader ... the image is crippled
in
the sense that it has no valid resolution information
something for hartmut to check in the img lib
Hm, I'm not sure. It's an image that could be correct, but TeX cannot
manage it.
It has 240x160 pixels and 1ppi, so it's 6,096 meters x 4,06400meters
and 6 meters are too much for TeX (which still has its limits around
5meters)
It's ok to print poster maybe, but then  TeX  is not the right tool.
yes, but the 1,1 resolution prevents us from doing anything useful, i.e. we
could for instance have something
if xresolution < 72 then xresolution = 72 end
but I'm not sure what the pdf backend will do as then the uses resolution
for front and backend differ too much
i'll add an overflow check but keep in mind that in that case scaling is
bases on the limited size
-----------------------------------------------------------------
                                          Hans Hagen | PRAGMA ADE
              Ridderstraat 27 | 8061 GH Hasselt | The Netherlands
    tel: 038 477 53 69 | voip: 087 875 68 74 | www.pragma-ade.com
                                             | www.pragma-pod.nl
-----------------------------------------------------------------
___________________________________________________________________________________
If your question is of interest to others as well, please add an entry to
the Wiki!
maillist : ntg-context@ntg.nl /
http://www.ntg.nl/mailman/listinfo/ntg-context
webpage  : http://www.pragma-ade.nl / http://tex.aanhet.net
archive  : http://foundry.supelec.fr/projects/contextrev/
wiki     : http://contextgarden.net
___________________________________________________________________________________

Re: [NTG-context] error when using externalfigure

Sietse Brouwer