blueprint for better resampling

[GoogleCodeExporter]

It more a blueprint than an issue

For raster document, it would be very wonderfull if resampling quality was 
enhanced by using better algorythm like "Bicubic interpolation"  

See attached files : the one (cropped et resampled manualy) with photoshop 
(using bicubic mode) has better readability/quality 

This filter exist in freeimage lib :
http://freeimage.sourceforge.net/fnet/html/494E93DF.htm
http://freeimage.sourceforge.net/fnet/html/2B709885.htm

If this is too complicated, a workaround could be to add an option in the 
config file to prevent resampling

I'm using the last version of papercrop 0.43 rev 19
I've tryed all options and to change lua code but i can't find a way to obtain 
good resampling nor prevent resampling

Original issue reported on code.google.com by leg...@gmail.com on 28 Dec 2010 at 8:18

Attachments:

• original.pdf
• with_papercrop.pdf
• with_photoshop.pdf

[GoogleCodeExporter]

I do not use any resampling in the code. The output images are directly 
rasterized from the poppler PDF library.
I could do supersampling + resampling but it would improve only scanned 
documents (or bitmap fonts), so it would be low priority for me. 
PaperCrop support only rasterized PDF outputs at the moment.
I would like to implement preserving original PDF objects, but I don't have 
much time these days.
Sorry,

Original comment by taesoob...@gmail.com on 29 Dec 2010 at 4:07

[GoogleCodeExporter]

[deleted comment]

[GoogleCodeExporter]

just FYI, if aliasing is problematic for most pdf files on your ebook devices, 
it could mean that the output resolution setting doesn't exactly match your 
ebook device.
For instance, most major ebook readers' optimal resolutions are slightly 
smaller than 600x800. (I don't remember exact resolution. My ebook reader 
support fullscreen.)
It is actually very tricky to find the right resolution that gives one-to-one 
pixel mapping, but it is possible. This setting is critically important to get 
satisfactory results.

Original comment by taesoob...@gmail.com on 29 Dec 2010 at 4:20

[GoogleCodeExporter]

Optionally added supersampling functionality at the svn repository. 
(Binary will be uploaded in a month after adding a few new features.)

Original comment by taesoob...@gmail.com on 11 Feb 2011 at 2:41

• Changed state: Accepted