[sane-devel] HP 5590 ADF end of page

[Ilia Sotnikov]

Gentlemen,
being author of the backend let me thank you for spotting the pixel
behavior. As I mentioned somewhat earlier I discovered the duplex mode
in original Windows driver occasionally. That means there some aspects
to be discovered such as the pixel indicator one.

Meanwhile, let's account for most of use cases - can you please redo
your experiments but with grayscale/BW modes? I'm wondering if there
would be similar indicator and would interesting to see its value for
both cases.

Also, we will still need to account for nearest paper size even with
pixel indicator, otherwise scanner might drop the indicator if scan
area is smaller than actual sheet. Another set of experiments would
shed some light on this as well.

Finally, some frontends might require user to account for doubled
count of output pages vs. fed ones (eg. Xsane if I remember
correctly), some doing continuos operation should handle this well
(eg. scanadf probably).

Hence, can you please conduct the following:
- redo scanning with ADF duplex, same parameters as you did previously
but with grayscale, and look for potential pixel indicator value?
- same as previous attempt, but with BW?
- same as first one but with paper size intentionally set smaller than
sheet being fed?
Then please report back your findings.

Unfortunately, I don't have access to the scanner model so will
totally rely on your input.

---
 Ilia Sotnikov

> On Nov 8, 2014, at 15:03, Protected <spamme at modanese.net> wrote:
>
> Hello Rainer,
>
> I have actually discovered yet another trick with the blue pixels: the
> pixel's blue RGB value is not random; in fact it even signals the end of
> the document (170 when there are pages left to be scanned, and 255 at
> the end of the document).
>
> In the meantime, I have also wrote a Perl script using ImageMagick to
> crop the images properly. Still, it would be nice having the driver do
> that automatically.
>
> ADF with 150 dpi does not look bad at all on my end.
>
> Best,
>
> Augusto
>
> Rainer Keller wrote:
>> Hello Augusto,
>>
>> I tried to handle the blue pixel as a page change.
>> Additional lines will be skipped until the blue pixel is found.
>> But now the scanimage tool will not terminate properly, maybe because just
>> skipping lines like I do is not the correct way to do this.
>>
>> See attached patch.
>>
>> Given the complexity of the sane code and limited spare time I tend more to
>> write a new frontend  to handle the page change marker. It could then also
>> handle the mirrored backsides.
>>
>> I tested it with duplex and 300 dpi.
>>
>> BTW, have you tried using the ADF with 150 dpi? For me the scanned images are
>> all bad.
>>
>> - Rainer
>
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