[NZLUG] Stitching 2x A4 images into A3

cr cr at orcon.net.nz
Sat Mar 26 13:26:09 NZDT 2016

On Sat, 26 Mar 2016 01:04:05 Volker Kuhlmann wrote:
> Thanks everyone, very helpful!
> > > > you'll never get the alignment bang-on-perfect, so you'll need to 
> > > > some
> > > > manual adjustments. which means gimp is the way to do it.
> Is there a function in gimp to kind of snap the alignment into place, or
> is it totally manual a la move/rotate until it looks like it fits?
I'm not sure about the 'snap-to' function, but what I found was that, when 
scanning, the page scanned was never quite 'square' to the image.   So 
there was nothing Gimp could 'get a grip' on to snap it into line.   I'd have 
to rotate the scan visually (which is where the superimposed grid was so 
useful), then crop it which automatically resulted in a squared-up image.   
Critical of course when joining maps edge-to-edge.

> > > > nb, adjusting the rotation will result in loss of detail, so you'll
> > > > need
> > > > to scan at a higher resolution than you think you'll need.
> Have you actually observed this? I didn't think re-sampling causes a
> noticable quality loss. Rotating things straight in vuescan must
> re-sample the data too and I haven't observed a visible difference.

I hadn't noticed a significant quality loss, there may have been some.   This 
was on colour maps; line diagrams might show it up more.

> > > Dedicated A3 scanners are horribly expensive, but some 'all-in-one'
> > > printer-copier-scanners are quite modestly priced (like my Epson
> > > WF-7510).
> That's an interesting tip, thanks. The current model seems to be 
> and can be had for $220. Maybe these days they are much better in
> scanning.
> Does anyone in Christchurch have something like this and would allow 
> to visit for a test scan? [offlist]
I just tried a colour photo - visiting card in my 7510  and the quality looked 
good to me.    Fairly slow at high resolutions, but good progressive 
contrast range.  But a test scan of your actual material would be a good 

> > Volker, I have a Fuji Xerox printer/scanner at work that does A3. If I can
> > assist at all, let me know. It'd have to be by arrangement as the 
> > is used pretty fulltime at work, but we could work something out.
> Thanks Nick, I'll keep it in mind, appreciate the offer but might have
> easier access to other offices.
> My experience with the scanning capabilities of big office machines
> about 4 years ago is very bad. They're fast, but that's all. The scan
> area doesn't match the plate position, output format can't be controlled
> (what's the point of creating a tiff with jpeg compression??), issues
> with print screens, and the worst was brightness/contrast control was
> not controllable and tuned to what photocopiers usually do. I'm not too
> hopeful that these things have changed, but it was using the device on
> its own. Using a scan program on the computer might knock it into 
> Something to test.

I found exactly the same with big office machines.    Quite hard to get a 
readable scan of a page of pencilled notes.    My old cheapie bought-in-
Foodtown(!) Artec 48 USB - slow as a wet week - was much better quality.

FWIW, Epson have a downloadable program called ScanImage! for Linux, 
seems to be a front-end for XSane.     I've used it and it works.   

(Disclaimer:  I don't have shares in Epson!   I believe Brother do a similar 


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