Scaling down the resolution of used pictures

Scaling down the resolution of used pictures

[Cecil Westerhof]

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At the moment it is not very important, but my other question remembered me
about an old situation.

I do not use graphics a lot in my ConTeXt files. But some time ago I used
several pictures with a very high resolution. This made the resulting PDF
very big. I did not expect the PDF printed on a printer with a higher
resolution as 1200 DPI. Is there a way to have the included graphics not be
bigger as necessary (without changing the original pictures)?

Again, at the moment it is not urgent. But when I come in the same situation
again, it would be nice if the resulting PDF was not five times as big as
necessary. And maybe the answer is useful for someone else also. ;-}

-- 
Cecil Westerhof

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Re: Scaling down the resolution of used pictures

[Martin Schröder]

2011/6/29 Cecil Westerhof <cldwesterhof@gmail.com>:
> I do not use graphics a lot in my ConTeXt files. But some time ago I used
> several pictures with a very high resolution. This made the resulting PDF
> very big. I did not expect the PDF printed on a printer with a higher
> resolution as 1200 DPI. Is there a way to have the included graphics not be
> bigger as necessary (without changing the original pictures)?

Use a program for image manipulation, e.g. ImageMagick.

Best
   Martin
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Re: Scaling down the resolution of used pictures

[Cecil Westerhof]

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2011/6/29 Martin Schröder <martin@oneiros.de>

> > I do not use graphics a lot in my ConTeXt files. But some time ago I used
> > several pictures with a very high resolution. This made the resulting PDF
> > very big. I did not expect the PDF printed on a printer with a higher
> > resolution as 1200 DPI. Is there a way to have the included graphics not
> be
> > bigger as necessary (without changing the original pictures)?
>
> Use a program for image manipulation, e.g. ImageMagick.
>

That would be a possibility, but I was wondering if there was a way to let
ConTeXt do it. Saves a lot of time. Also: when changing from A4 to A5, you
have to do it all over again.

-- 
Cecil Westerhof

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Re: Scaling down the resolution of used pictures

[Henning Hraban Ramm]

Am 2011-06-29 um 17:01 schrieb Cecil Westerhof:

> That would be a possibility, but I was wondering if there was a way  
> to let ConTeXt do it. Saves a lot of time.

There once was t-degrade module: http://modules.contextgarden.net/t-degrade
I guess the modern way would be using t-filter: http://modules.contextgarden.net/filter


Greetlings from Lake Constance!
Hraban
---
http://www.fiee.net/texnique/
http://wiki.contextgarden.net
https://www.cacert.org (I'm an assurer)

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Re: Scaling down the resolution of used pictures

[luigi scarso]

On Wed, Jun 29, 2011 at 5:01 PM, Cecil Westerhof <cldwesterhof@gmail.com> wrote:
> 2011/6/29 Martin Schröder <martin@oneiros.de>
>>
>> > I do not use graphics a lot in my ConTeXt files. But some time ago I
>> > used
>> > several pictures with a very high resolution. This made the resulting
>> > PDF
>> > very big. I did not expect the PDF printed on a printer with a higher
>> > resolution as 1200 DPI. Is there a way to have the included graphics not
>> > be
>> > bigger as necessary (without changing the original pictures)?
>>
>> Use a program for image manipulation, e.g. ImageMagick.
>
> That would be a possibility, but I was wondering if there was a way to let
> ConTeXt do it.
still not without an external program, but I hope for Porquerolles.

-- 
luigi
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Re: Scaling down the resolution of used pictures

[Hans Hagen]

On 29-6-2011 5:01, Cecil Westerhof wrote:
> 2011/6/29 Martin Schröder<martin@oneiros.de>
>
>>> I do not use graphics a lot in my ConTeXt files. But some time ago I used
>>> several pictures with a very high resolution. This made the resulting PDF
>>> very big. I did not expect the PDF printed on a printer with a higher
>>> resolution as 1200 DPI. Is there a way to have the included graphics not
>> be
>>> bigger as necessary (without changing the original pictures)?
>>
>> Use a program for image manipulation, e.g. ImageMagick.
>>
>
> That would be a possibility, but I was wondering if there was a way to let
> ConTeXt do it. Saves a lot of time. Also: when changing from A4 to A5, you
> have to do it all over again.

You can plugin in a converter. However, it only works for one to anothe 
format so you need to patch a line in grph-inc.lua:

line 416: local converter = (newformat ~= format or resolution) and 
converters[format]

(I'll figure out something better for this so it's a temp hack.)

Such a plugin looks like:

\startluacode
figures.converters.png = {
     png = function(oldname,newname,resolution)
         local command = string.format('gm convert -depth 1 "%s" 
"%s"',oldname,newname)
         logs.report(string.format("running command %s",command))
         os.execute(command)
     end
}
\stopluacode

\externalfigure[mill.png][resolution=lowres,conversion=png]


Hans

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Re: Scaling down the resolution of used pictures

[Aditya Mahajan]

On Wed, 29 Jun 2011, Hans Hagen wrote:

> Such a plugin looks like:
>
> \startluacode
> figures.converters.png = {
>    png = function(oldname,newname,resolution)
>        local command = string.format('gm convert -depth 1 "%s" 
> "%s"',oldname,newname)
>        logs.report(string.format("running command %s",command))
>        os.execute(command)
>    end
> }
> \stopluacode

Don't you need to use 'resolution' somewhere in the function?

> \externalfigure[mill.png][resolution=lowres,conversion=png]

Aditya
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Re: Scaling down the resolution of used pictures

[Hans Hagen]

On 29-6-2011 7:20, Aditya Mahajan wrote:
> On Wed, 29 Jun 2011, Hans Hagen wrote:
>
>> Such a plugin looks like:
>>
>> \startluacode
>> figures.converters.png = {
>> png = function(oldname,newname,resolution)
>> local command = string.format('gm convert -depth 1 "%s"
>> "%s"',oldname,newname)
>> logs.report(string.format("running command %s",command))
>> os.execute(command)
>> end
>> }
>> \stopluacode
>
> Don't you need to use 'resolution' somewhere in the function?

Well, not 'need' but it would make sense of course to use that info, for 
instance to set the depth or resolution but I wasn't in the mood for 
studying the man pages (and I always forget the command line arguments), 
so I leave that 'as an exercise for the reader'.

Hans

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                                           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
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Re: Scaling down the resolution of used pictures

[Peter Münster]

On Wed, Jun 29 2011, Hans Hagen wrote:

>> That would be a possibility, but I was wondering if there was a way to let
>> ConTeXt do it. Saves a lot of time. Also: when changing from A4 to A5, you
>> have to do it all over again.
>
> You can plugin in a converter. However, it only works for one to anothe format
> so you need to patch a line in grph-inc.lua:

Could img.copy() help here perhaps?

-- 
           Peter
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Re: Scaling down the resolution of used pictures

[Hans Hagen]

On 29-6-2011 9:43, Peter Münster wrote:
> On Wed, Jun 29 2011, Hans Hagen wrote:
>
>>> That would be a possibility, but I was wondering if there was a way to let
>>> ConTeXt do it. Saves a lot of time. Also: when changing from A4 to A5, you
>>> have to do it all over again.
>>
>> You can plugin in a converter. However, it only works for one to anothe format
>> so you need to patch a line in grph-inc.lua:
>
> Could img.copy() help here perhaps?

that's unrelated,

Hans

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                                           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
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