[sane-devel] option threshold without effect for fujitsu backend since 1.0.24-1

[m. allan noah]

Mickael, thank you for the report. I thought I had fixed this problem
previously, but I am apparently wrong. I will investigate.

allan

On Mon, Oct 3, 2016 at 12:13 PM, PELUARD Mickael
<mickael.peluard at smart-rx.com> wrote:
> Hello,
>
>
>
>                 we used Fujitsu scanner (fi-5110 / fi-5120 / fi-6110) for a
> long time with an old linux plateform and sane (1.0.22-9). These scanners
> used the fujitsu backend.
>
>
>
>                 We have recently changed to RHEL-6 with sane-backends-1.0.21
> and to Debian with libsane-1.0.25.
>
>
>
>                 We scan in lineart mode and we only put the threshold option
> to reduce the size of document : scanimage –d ‘fujitsu:XXX:XXX’ --resolution
> 150  --mode lineart  --threshold 140
>
>                 Then we convert the image to PDF-A1. With the old plateform
> and rhel-6, no problem. But with Debian and sane-1.0.25, the size of the
> documents increase a lot.
>
>
>
> Using a reference document, we get the following results with a fi-6110 :
>
> -          Rhel-6 / sane-1.0.21 = around 50 ko
>
> -          Debian / sane-1.0.25-2 = around 350 ko
>
> It’s quite the same problem if we used a fi-5110c and fi-5120c.
>
>
>
> I downgrade the libsane package and look the result :
>
> -          Debian / libsane-1.0.22-7 = good
>
> -          Debian / libsane-1.0.23-3+b1 = good
>
> -          Debian / libsane-1.0.24-1 = NOT GOOD
>
> -          Debian / libsane-1.0.24-8u5 = NOT GOOD
>
> -          Debian / libsane-1.0.26Git = NOT GOOD
>
>
>
> I change the value of threshold on Debian with sane-1.0.25 : threshold 0 or
> 200. But the image don’t change. It’s look like the threshold option has not
> effect.
>
> To reduce the problem, I play with the contrast and brightness option but
> the result is not entirely satisfactory.
>
>
>
> I think the problem is on the threshold option of the fujitsu backends.
>
>
>
> It is probably the same bug but it don’t lokk corrected in 1.0.26 :
>
> https://alioth.debian.org/tracker/?group_id=30186&atid=410366&func=detail&aid=315069
>
>
>
> Cordially.
>
>
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