Has DigiKam a limit on file sizes?

[Remco Viëtor]

On samedi 21 janvier 2017 09:11:11 CET jdd wrote:
> > Em 20 de jan de 2017 18:07, "Arran" <digikam.bruno at arranmarketing.com
> > 
> > <mailto:digikam.bruno at arranmarketing.com>> escreveu:
> >     Hello
> >     I am scanning pictures my wife draws analogue with crayons, some
> >     coloured
> >     and some black/white. They all base on an good and strong A4 paper.
> >     I scan
> >     them (Epson) with 2400 dpi, and receive usually files of about 4 to
> >     7 MB as
> >     *.png files. Saved with TIFF is usually over 30MB, but several tests
> >     we
> >     produced are not showing any real improvement.
> 
> most photocopy machine use as low as 150 dpi, 300 dpi for an A4 is more
> than enough
> 
> >     printing. However, the original scaned *.pdf
> 
> you said you scanned as *png*. png are images, pdf are not. jpg is
> probably enough for your use.
As 'Arran' is scanning drawings, i.e. basically line-art, jpg is not a 
recommended format at all due to the "ringing" it always will cause near sharp 
edged. That "ringing" is a direct result of the compression method and cannot 
be avoided (look up Fourier or Cosine transform). 

My choice would also have been png, as it's lossless, supports 16 bit/channel 
and alpha. For such single layer images I see no reason to use TIFF (and 
several reasons to avoid it: size and number of dialects).

But PDF is indeed an odd choice to store images in. You'll probably need it to 
print the image, and might want to keep it as a kind of cache, but it's not 
good as a master image (that would be the original .png with the modified 
.xcf).

Remco