Re: scanning negatives using HP4850 and genesys backend
Ralph Little <[email protected]> Fri, 31 Jul 2026 10:18:26 -0700
| Newsgroups | gmane.comp.graphics.scanning.sane.devel |
|---|---|
| Message-ID | <[email protected]> |
This is a multi-part message in MIME format. --------------nwM98YrI2zhOGEX7o2EBiKwU Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit Hi, There are other backends that support transparency but the genesys chips are pretty much a world of their own. On the upside, the GL646 is pretty well documented. I believe the main ways in which the transparency support would be invoked would be via the source and options related to capture type. I don't see any specific image capture type-related options in the backend but some would have to be added I suspect (e.g. for selecting between positive and negative, IR etc). The main challenge with genesys-based devices is that every model is different to every other in implementation. The Genesys chips are very flexible and offer all sorts of driving options and they need to be set up for the particular hardware that they are matched with. The main way to tackle this task is to observe Windows driver behaviour through capturing traffic and looking at the register values that are set. It's a little more involved but that is the main gist. I have had some dealings myself with looking at a GL646 device before although it was a fairly superficial look at motor stepping tables but I may be able to look at it in the future sometime. One thing you *can* do (if you have the inclination) is to make some USB captures on Windows and post them to an issue at our GitLab issue tracker (https://gitlab.com/sane-project/backends/-/work_items), if you don't intend to do the implementation yourself. That way someone could pick up the issue at some point. Ideally a developer needs the hardware at hand, but a rough stab could be made by looking at the traffic. Cheers, Ralph On 2026-07-31 10:01, [email protected] wrote: > > Ralph, > > Thanks for the reply. > > I looked at the Genesys Datasheet for the chip (GL646USB) that is used > in the HP4850. I see the register that appears to control the slide > scanning lamp. > > Is there another backend that has support for a similar feature? > Possibly I could use that as a template to better understand how > support for this feature might be implemented in the genesys backend. > > Thanks again, > > Jon > > > On 7/31/26 11:21 AM, Ralph Little wrote: >> Hi, >> According to our Supported Scanners list >> (http://www.sane-project.org/sane-supported-devices.html) the genesys >> backend doesn't yet support the slide scanning feature of this >> device. It requires additional code to drive the extra hardware involved. >> We don't have an active maintainer for the genesys backend at the >> moment unfortunately, so I don't know when someone would be able to >> get to this task in the future. :( >> >> Regards, >> Ralph >> >> On 2026-07-30 20:58, [email protected] wrote: >>> >>> |I recently acquired an HP Scanjet 4850 scanner. The document >>> scanning works with no problems. This particular scanner has a >>> negative/slide scanning component built in to the lid of the >>> device. This includes a separate lamp to illuminate the film for >>> scanning. The lamp in the lid comes when I run a hardware self test >>> procedure but I have not discovered any way to have the lamp come on >>> when scanning using sane. >>> >>> Is this capability supported? >>> >>> info about my setup --- >>> >>> HP Scanjet 4850 >>> >>> $ scanimage -V >>> scanimage (sane-backends) 1.4.0; backend version 1.4.0 >>> >>> genesys backend >>> >>> Fedora Linux 44 (Workstation Edition) >>> Linux 7.1.5-200.fc44.x86_64| >>> >> --------------nwM98YrI2zhOGEX7o2EBiKwU Content-Type: text/html; charset=UTF-8 Content-Transfer-Encoding: 8bit <!DOCTYPE html> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> </head> <body> Hi,<br> There are other backends that support transparency but the genesys chips are pretty much a world of their own. On the upside, the GL646 is pretty well documented.<br> I believe the main ways in which the transparency support would be invoked would be via the source and options related to capture type. I don't see any specific image capture type-related options in the backend but some would have to be added I suspect (e.g. for selecting between positive and negative, IR etc).<br> <br> The main challenge with genesys-based devices is that every model is different to every other in implementation. The Genesys chips are very flexible and offer all sorts of driving options and they need to be set up for the particular hardware that they are matched with. The main way to tackle this task is to observe Windows driver behaviour through capturing traffic and looking at the register values that are set. It's a little more involved but that is the main gist.<br> <br> I have had some dealings myself with looking at a GL646 device before although it was a fairly superficial look at motor stepping tables but I may be able to look at it in the future sometime.<br> One thing you *can* do (if you have the inclination) is to make some USB captures on Windows and post them to an issue at our GitLab issue tracker (<a class="moz-txt-link-freetext" href="https://gitlab.com/sane-project/backends/-/work_items">https://gitlab.com/sane-project/backends/-/work_items</a>), if you don't intend to do the implementation yourself. That way someone could pick up the issue at some point. Ideally a developer needs the hardware at hand, but a rough stab could be made by looking at the traffic.<br> <br> Cheers,<br> Ralph<br> <br> <div class="moz-cite-prefix">On 2026-07-31 10:01, <a class="moz-txt-link-abbreviated" href="mailto:[email protected]">[email protected]</a> wrote:<br> </div> <blockquote type="cite" cite="mid:[email protected]"> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <p>Ralph,</p> <p>Thanks for the reply.<br> <br> I looked at the Genesys Datasheet for the chip (GL646USB) that is used in the HP4850. I see the register that appears to control the slide scanning lamp.</p> <p>Is there another backend that has support for a similar feature? Possibly I could use that as a template to better understand how support for this feature might be implemented in the genesys backend.</p> <p>Thanks again,</p> <p>Jon</p> <p><br> </p> <div class="moz-cite-prefix">On 7/31/26 11:21 AM, Ralph Little wrote:<br> </div> <blockquote type="cite" cite="mid:[email protected]"> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> Hi,<br> According to our Supported Scanners list (<a class="moz-txt-link-freetext" href="http://www.sane-project.org/sane-supported-devices.html" moz-do-not-send="true">http://www.sane-project.org/sane-supported-devices.html</a>) the genesys backend doesn't yet support the slide scanning feature of this device. It requires additional code to drive the extra hardware involved.<br> We don't have an active maintainer for the genesys backend at the moment unfortunately, so I don't know when someone would be able to get to this task in the future. :(<br> <br> Regards,<br> Ralph<br> <br> <div class="moz-cite-prefix">On 2026-07-30 20:58, <a class="moz-txt-link-abbreviated moz-txt-link-freetext" href="mailto:[email protected]" moz-do-not-send="true">[email protected]</a> wrote:<br> </div> <blockquote type="cite" cite="mid:[email protected]"> <meta http-equiv="content-type" content="text/html; charset=UTF-8"> <p><code>I recently acquired an HP Scanjet 4850 scanner. The document scanning works with no problems. This particular scanner has a negative/slide scanning component built in to the lid of the device. This includes a separate lamp to illuminate the film for scanning. The lamp in the lid comes when I run a hardware self test procedure but I have not discovered any way to have the lamp come on when scanning using sane.<br> <br> Is this capability supported?<br> <br> info about my setup ---<br> <br> HP Scanjet 4850<br> <br> $ scanimage -V<br> scanimage (sane-backends) 1.4.0; backend version 1.4.0<br> <br> genesys backend<br> <br> Fedora Linux 44 (Workstation Edition)<br> Linux 7.1.5-200.fc44.x86_64</code></p> </blockquote> <br> </blockquote> </blockquote> <br> </body> </html> --------------nwM98YrI2zhOGEX7o2EBiKwU--