Re: [libdmtx-development] Unable to decode datamatrix barcode in 640x480 BMP format

[Hector G. de M. <no...@gm...>]

I agree with Nick. Try to pre process your raw image a little bit in order
to reduce some possible sources of noise. It seems that you are working
under a controlled environment,
so there should be a systematic way to pre-process your input images.


On Thu, Oct 24, 2013 at 8:06 PM, Nick Irvine <nfi...@nf...> wrote:

> I'm no expert on the subject, so grain of salt, but here's my two cents.
>
> When you scale an image down, you sharpen soft edges.  Say you've got
> a somewhat blurry edge that's 10px and has an intensity gradient of
> 25%.  Scaling the image to 50% scales that gradient, so it'll be 50%
> over 5px.    And that's how libdmtx detects edges, by the gradient
> slope, aka threshold.
>
> readdtmx has a setting for this: --threshold.  Try lowering that.
>
> Also try the --shrink option to get dtmxread to shrink the image for you.
>
>
> Nick
>
> On Thu, Sep 26, 2013 at 9:45 PM, gian hatams <gra...@gm...>
> wrote:
> > I am having problems decoding a 640x480 image using the command "dmtxread
> > 640x480.bmp". However if I ran the scaled down version of the same file
> > (i.e. 320x240) I can get dmtxread decode the barcode.
> >
> > I am using dmtxread/libdmtx version 0.7.2
> >
> > I attached both files for reference. But I must be missing something
> > fundamental here.
> >
> > I would appreciate any advice.
> >
> > Best Regards,
> > GH
> >
> >
> >
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-- 
Héctor
Webpage: http://mathtronics.wordpress.com/