Web lists-archives.com

Re: [OT] scanned files are large in size




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.

> > 2) Is the difference in image sizes due to the bpc (1 vs. 8) or
> > encoding (ccitt vs jped) fields?
>
> CCITT vs JPEG, yes.
>

ok. What about bpc? Does that matter for file size?

> > 3) If yes, how to change them?
>
> Hmmm. I don't know yet whether you have to talk to your scanner
> or to your scan software...

I think there is not much I can do from the scanner's settings. But I
was wondering if I can use some software (like convert, gs etc.,) to
change the encoding, bpc etc., and reduce the file sizes without
sacrificing too much on the quality. To be honest, both files look the
same when viewed side by side.

-- 
Kamaraju S Kusumanchi | http://raju.shoutwiki.com/wiki/Blog