Re: shrink JPGs to some resolution (dpi) ?

[Hans Hagen <pragma@wxs.nl>]

On 3/10/2015 12:18 AM, Harald Koenig wrote:
> On Mar 09, Hans Hagen wrote:
>
>> On 3/9/2015 10:50 PM, Alan BRASLAU wrote:
>>
>>> This can be done once and is much better than getting ConTeXt to
>>> convert every time on the fly.
>>
>> Do you really think that we let context convert a big file each run
>> in a critical workflow? Context will only resample when an image
>> file changed (which happens when you have to process from
>> repositories updated by authors).
>
> I guess that's a question for me ?

More for Alan.

> of course I don't plan to run context on the big files every time -- as I know that that's still way too slow;)
> but it would be nice if I don't need magic external tools to guess
> the correct physical print size, calculate the actual number of pixels for e.g. 300 dpi, etc.

150 pixels is probably enough for color print ... if you have raw files 
you can also consider png

anyway, i need to think a bit about it but we do have all the info 
available, like

- needed width/height
- original width/height

and from that we can calculate some conversion parameters

if it would help you i can provide a tracker that will save info like 
this (per image):

  ["used"]={
   ["colordepth"]=0,
   ["depth"]=0,
   ["format"]="pdf",
   ["fullname"]="t:/sources/cow.pdf",
   ["height"]=13156352,
   ["name"]=false,
   ["pages"]=1,
   ["path"]=false,
   ["suffix"]=false,
   ["width"]=18089984,
   ["xresolution"]=0,
   ["xsize"]=18089984,
   ["yresolution"]=0,
   ["ysize"]=13156352,
  },

> finally I like the idea to be able to create the final PDF in a "single" context run
> from *original* source (== original JPGs) without lots of additional tools and steps/scripts
> (or if I want to start over "form scratch" from input files).

that is what we also prefer: only luatex/mkiv + gm / gs

Hans

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