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Re: [OT] scanned files are large in size




On Wed 02 Jan 2019 at 14:44:14 (+0000), Brian wrote:
> On Tue 01 Jan 2019 at 22:41:06 -0500, kamaraju kusumanchi wrote:
> 
> > On Tue, Jan 1, 2019 at 1:40 PM <tomas@xxxxxxxxxx> wrote:
> > >
> > > Yep. The one image is encoded as CCITT (aka Group 4, aka fax [1]), which is
> > > passable for low res B&W images, but not that much for hi-res or color (or
> > > gray scale). It compresses much worse than the other which is JPEG, which is
> > > expressly made for hi-res and color (or grayscale) images.
> > >
> > > OTOH, CCITT is lossless and JPEG lossy ;-)
> > >
> > ok, thanks.
> > 
> > > > Questions:
> > > > 1) Does the large file size have anything to do with the printer
> > > > itself? Is there anything I can do (ex:- update the driver/firmware or
> > > > something)?
> > >
> > > That depends on what is encoding the images: does the scanner itself
> > > "make" the PDF? Or some software, computer-side?
> > >
> > 
> > The scanner itself makes the pdf files.
> 
> I'm intrigued; I hadn't realised that conversion of the scanned image
> for some vendors' devices took place on the device itself. How do you
> know this happens? It is the frontend to SANE (xsane or scanimage, for
> example) which I've always associated with image aquisition conversion.

It really is rather easy. You insert a USB stick into the scanner,
press scan, and later observe that a JPEG or PDF file has appeared
on the stick, as appropriate.

Cheers,
David.