HP 6950 sane driver only scans the upper part of the page with lineart mode

[Sergio Callegari]

On Kubuntu 17.04, with hplip 3.16.11 and recent sane (from sane git via the ubuntu sane ppa), trying to scan from an HP 6950 via xsane does not work in lineart mode unless JPEG compression is requested (which should be meaningless for lineart)

Specifically:

trying to scan an A4 page only the top 4cm of the page are saved

[Sergio Callegari (callegar)]

Activating the JPEG compression (which should not be available in lineart as it makes no sense for this mode) seems to relax the issue

[Sergio Callegari (callegar)]

The same happens also with hp-scan, that says
"Read 1.0 MB from scanner.
error: Did not read enough data from scanner (I/O Error?)"

[Sergio Callegari (callegar)]

As a matter of fact, with hp-scan, the matter is worse:

1) Scanning in lineart mode fail with not enough data either with and without jpeg compression. In either case, scanning an A4 page in lineart at 300 dpi, the scan ends after 1 MB of data is read. Interestingly, 1 MB of data should indeed correspond to an A4 page at 300 dpi, 1 bit per pixel. Yet when the scan ends, the progess bar is at about 1/8 of fullscale.

2) In grayscale mode, the compression switch is recognized (the textual output of hp-scan reports it correctly), but ignored. Either with or without compression scanning an A4 paper in grayscale at 300 dpi reports 8.3 MB of data which is consistent with a raw 300dpi scan with 8 bits per pixel.

[Joseph Florio (joeinslw)]

Xsane doesn't seem to support Flatbed setting either, I'm thinking there is
a bug in it, and uninstalling and reinstalling it won't work either because
the bug is in the software at the source.
I think someone is hacking into the software, planting bugs so that Linux
won't work, we get disgusted and go back to Microsoft?
Not me, NEVER, Linux needs to fix it at their end, then put out a correct
disc, then tell us the corrected software is available, it's the only way,
so Linux software won't get infected again.

On Wed, Jul 12, 2017 at 4:40 PM, Sergio Callegari <
<email address hidden>> wrote:

> Public bug reported:
>
> On Kubuntu 17.04, with hplip 3.16.11 and recent sane (from sane git via
> the ubuntu sane ppa), trying to scan from an HP 6950 via xsane does not
> work with the ADF.
>
> Specifically:
>
> trying to scan an A4 page, the page is passed through the ADF correctly,
> but only the top 4cm of the page are saved
>
> ** Affects: hplip
> Importance: Undecided
> Status: New
>
> --
> You received this bug notification because you are subscribed to HPLIP.
> Matching subscriptions: joeinslw
> https://bugs.launchpad.net/bugs/1703982
>
> Title:
> HP 6950 sane driver only scans the upper part of the page with lineart
> mode
>
> Status in HPLIP:
> New
>
> Bug description:
> On Kubuntu 17.04, with hplip 3.16.11 and recent sane (from sane git
> via the ubuntu sane ppa), trying to scan from an HP 6950 via xsane
> does not work with the ADF.
>
> Specifically:
>
> trying to scan an A4 page, the page is passed through the ADF
> correctly, but only the top 4cm of the page are saved
>
> To manage notifications about this bug go to:
> https://bugs.launchpad.net/hplip/+bug/1703982/+subscriptions
>

[Sergio Callegari (callegar)]

@ Florio

> I think someone is hacking into the software, planting bugs so that Linux won't work, we get disgusted and go back to Microsoft?
> Not me, NEVER, Linux needs to fix it at their end, then put out a correct disc, then tell us the corrected software is available, it's the only way, so Linux software won't get infected again.

Please, don't make this bug report totally useless and something the hplip devel will dislike reading.

[Sergio Callegari (callegar)]

Can someone please indicate:

1) Whether this is actually the place that upstream hplip developers use to track bugs or the ubuntu only downstream bug tracker for hplip? The hplip site seems to suggest the former, but I wonder if I am reporting the issue in the correct place.

2) Whether this issue might have been addressed in hplip 3.17.x, since the changelogs on the hplip site are extra terse and no mention of this issue appears there.

3) Whether there is a packaged 3.17.x to test. The hp hplip site claims that "Ubuntu 17.04 supplies HPLIP 3.17.5 and it does support your printer" which does not seem to be the case. On 17.04, I have hplip 3.16.11 and no option to upgrade.

These info would be quite precious to decide what to do with the printer.

Incidentally, if the issue is not fixed in 3.17.x, in case HP personnel reads this page, I suggest to modify the Officejet support page (http://hplipopensource.com/hplip-web/supported_devices/officejet.html) to say that the support for the 6950 is only partial and not full, which would guide customers better.

[Sergio Callegari (callegar)]

Made a quick test, forcing the install of libsane-hpaio_3.17.7+repack0-3_amd64.deb from artful. This makes the package manager complain a little about broken dependencies, but there does not seem to be any fundamental breakage as sane still works.

Unfortunately the issue persists and lineart (black and white) scanning remains badly broken on the 6950 even with the latest libsane-hpaio_3.17.7.

[Sergio Callegari (callegar)]

Looks like there is no activity from upstream. Please consider marking this all-in-one as only partially supported downstream since scanner does not work properly. There are a lot of HP printers that work fine and guiding the user to them seems proper.

[Sergio Callegari (callegar)]

As expected the issue is also present in ubuntu artful.

[Sergio Callegari (callegar)]

Also present in bionic.

[Sergio Callegari (callegar)]

Fixed my issue by moving to a different printer/multifunction device. From now on I will not be able to make any test about this issue. Please consider closing the issue and simply marking the HP6950 as poorly supported by HPLIP, so that people shopping for printers that work well with ubuntu can make an informed choice.

[Bill Yikes (yik3s)]

hp-scan still has this defect in version 3.22.10. Output looks like this:

Warming up...

Page 1: Scanning...
Reading data: [*****************************************************************************************************] 100% 1.1 MB
Read 1.1 MB from scanner.
error: Did not read enough data from scanner (I/O Error?)
Closing device.

[Bill Yikes (yik3s)]

Note someone duplicated this bug report here:

https://bugs.launchpad.net/hplip/+bug/1915029

[Bill Yikes (yik3s)]

I should also mention the problem manifests with the Officejet Pro 8610, since hardware model seems relevent IIUC.

[Sergio Callegari (callegar)]

Seeing your post I have just re-checked. On the Color Laserjet Pro MFP M281fdw the behavior is now rather erratic. Generally lineart scanning works with JPEG compression (that unfortunately is not exactly what you want with lineart). In a couple of occasions lineart scanning even worked even with no compression. But in most cases, with no compression it errors out or, more frequently, it causes the client program (e.g., xsane) to crash and dump core.

Would not have high hopes to see this fixed, though.

It is not only that this issue has now been open for 7 years. More generally, hplip does not appear to be maintained, at least according to the meaning that most users wouold associate to the word, no matter the existence of this tracker. The code happens see new releases as new products go to the market, but in my experience issues seen in current or old products don't get fixed and this tracker is more or less ignored. As an example, the same Color Laserjet Pro MFP M281fdw has never been capable of obeying the option to print in grayscale in Linux using the upstream hplip (and this is an "expensive" and anti-ecologic bug).

Clearly, I'd love to be proved wrong, but IMHO you should really use this tracker mostly as a means to check if something that you observe is a local issue (that can probably be addressed on your system) or a bug in hplip or the printer firmware. In the latter case, you'll probably have to live with it, even if in some cases the reporters suggest useful workarounds... Another use of the traker is obviously to avoid the most faulty models. So, please keep reporting because in any case the tracker can really be useful.

Wrt your issue, a possibility, if you have a recent enough printer, is to avoid hplip altogether. Driverless printing and scanning (escL/airscan) appears to be the future, no matter how much limiting they are wrt the potential device capabilities. For instance, driverless escL scanning works perfectly with the MFP M281fdw, saves from the use of plugins, and avoids the lineart issue altogether by not providing at all the no-compression mode and the lineart mode. May seem limiting, but in fact it is better not to advertise half-broken functionalities, at least it does not confuse users.