Re: Which Image quality should I use ?

[Hans Hagen <pragma@wxs.nl>]

On 7/15/2014 7:03 PM, Peter Münster wrote:
> On Sun, Jul 13 2014, Pol Stra wrote:
>
>>> I can be done automatically for example by using this module:
>>> http://modules.contextgarden.net/grph-downsample
>>
>> Thank you, it looks interesting. Is there a documentation somewhere or could
>> you provide an example about how to use it ?
>
> Hi,
>
> Here an example: http://wiki.contextgarden.net/Catalogue_raisonné
>
>
>> Also, it changes the resolution only at inclusion into the pdf or it does it
>> on original files ? My concern is to give the sources in attachment of the
>> document, so if I don't change those files, the document will still be huge.
>
> The downscaled images are kept on disk in the "cache" sub-directory.
>
>
>> There is a way to include the source without duplicates images ?
>
> Yes.
>
>
> There is also an old module t-degrade.tex but I don't know, if it still
> works with recent ConTeXt versions.

so you have several options:

- using build in
- using specific modules

built in boils down to something

\startluacode

figures.converters["png"] = {
     ["lowres.png"] = function(oldname,newname,resolution)
         os.execute(string.format('gm convert -depth 1 "%s" 
"%s"',oldname,newname))
     end,
}

-- figures.suffixes["lowres.png"] = figures.suffixes.png -- suffix is 
automatically done

\stopluacode

\starttext
     \externalfigure[mill.png][conversion=lowres.png]
\stoptext

in nearly all our projects we get images that need to be converted 
(color -> bw, downsampling, removing crap from pdf, etc) but in most 
cases we also convert to pdf then because that is normally the fastest 
way to include an image (which is why one can also define a prefix and 
cache)

what method you choose depends on how much control you want (it's hard 
to predict demands) ... btw, many of these build-in mechanism are 
derived from mkii methods, where we also had resource manipulators and 
so (we still have figure databases btw)

Hans

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                                           Hans Hagen | PRAGMA ADE
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