Hi developers, I finally started having a look at the coolscan2 backend. For my first patch I added a new option, --quality, that may be used to activate the "high quality scan" scanner option.
The patch is against the current CVS tree. I would like to receive some comments, if anyone have enough time and will to test this patch. I tested it with black and white negative film stripes (I also used the CS2_BLEEDING_EDGE define in order to activate the --negative option) and with framed slides. My next work will be on activating a new option, --greyscale, in order to scan in greyscale instead of RGB. Thanks, Giuseppe P.S. I think that the code surrounded by #ifdef CS2_BLEEDING_EDGE could be activated without this define. I mean that my tests show that this code works. -------------- next part -------------- A non-text attachment was scrubbed... Name: sane-coolscan2-quality.patch Type: text/x-patch Size: 5904 bytes Desc: not available Url : http://lists.alioth.debian.org/pipermail/sane-devel/attachments/20070225/da4391c7/sane-coolscan2-quality.bin From [email protected] Sun Feb 25 12:32:20 2007 From: [email protected] (Giuseppe Sacco) Date: Sun Feb 25 12:29:17 2007 Subject: [sane-devel] [patch] --quality scan option for coolscan2 backend In-Reply-To: <20070225101340.GA2552@ventus> References: <1172394840.20976.7.camel@scarafaggio> <20070225101340.GA2552@ventus> Message-ID: <1172403140.20976.38.camel@scarafaggio> Hi Andras, Il giorno dom, 25/02/2007 alle 11.13 +0100, Major A ha scritto: > > I finally started having a look at the coolscan2 backend. For my first > > patch I added a new option, --quality, that may be used to activate the > > "high quality scan" scanner option. > > Thanks for taking over. I really don't have any time to spend on SANE > at the moment. But what, exactly, is the high-quality option? Do you > mean multisampling? For that to work, it's not sufficient to just set > the relevant bits before scanning, you also have to actively read out > the lines and sum them up yourself, the scanner doesn't do it for > you. Also, not that not all scanners support multisampling. Also, if > you mean multisampling, I'd call the option accordingly because > "high-quality" doesn't really mean a lot. This is not the multiread option, that you described. It is a different option. If you have the Nikon specification called "COOLSCAN V ED I/F PROTOCOL SPECIFICATIONS", its first description is in byte 5 of SET WINDOW command. The documentation doesn't describe the difference when setting or clearing the bit. The documentation also says that this bit is not used with LS-50 and LS-5000 so I don't know what scanner would/will use it. I did this patch just for studying the coolscan2 code and the SANE API. > > My next work will be on activating a new option, --greyscale, in order > > to scan in greyscale instead of RGB. > > Again, the scanner doesn't support that in hardware. And because it > doesn't, I think it's better to scan RGB and leave the conversion to > greyscale to the frontend or the user. (The scanner does have a > single-colour mode, but that isn't greyscale, you can select one of > the colour channels to be scanned exclusively, but I wouldn't call > that greyscale). You are right. I use scanimage and get ~60Mb for each scan at 4000dpi. This is a bit overkill, so I would like to save tiff images in greyscale instead of rgb colour. Currently I scan images with scanimage/coolscan2 and then convert to greyscale using netpbm or gimp. I saw that coolscan2 backend already does an exposure with different values for r (1200), g (1200) and b (1000), but I don't know what this implies when using b/w negative films. I know that ppmtopgm (from netpbm) uses .299 r + .587 g + .114 b for its conversion. Does this means that I should use the same exposure time for all tree colour components? Another question for scanimage is: could it be converted for using libtiff? This would probably increase quality and add support for, among other things, compressed tiff files. > BTW, has anyone got the LS-50/5000 working in the end? I am working with an LS-50. I also used the --negative option very extensively, but I am currently working only with b/w films. Bye, Giuseppe
