[sane-devel] Fwd: HP scanjet IIcx /t resolution

Peter Kirchgessner peter@kirchgessner.net
Mon, 06 Sep 2004 20:51:52 +0200


the HP SCL documentation says that the IIcx has a native resolution of 
400 dpi and that it supports grayscale and color scans of 8 bits per 
channel. So scanning at more than 400 dpi does not give more details.
When selecting to do color scans, it will scan with 3x8 bits = 24 bits 
which is about 16.777.216 possible colors. More colors are not supported.


George Georgalis schrieb:
> On Mon, 6 Sep 2004 15:22:42 +0100, Martin Collins <martin@mkcollins.org> wrote:
>>On Sat, 4 Sep 2004 18:21:11 -0400
>>George Georgalis <georgalis@gmail.com> wrote:
>>>It's spec says 600 dpi but somewhere between 300 and 400 dpi it
>>>starts to do double passes (exactly when it starts depends on the
>>>image). I think I understand what's happening, though I don't know
>>>the vocabulary to explain it (software gets a higher resolution than
>>>the optical quality requiring multiple passes).
>>You are thinking of "software interpolation". That's not it though.
>>I would call this behaviour "backtracking" and like Abel says it is
>>probably due to a bottleneck in the data path.
>>Are you using the SCSI card that came with the scanner? Does it have
>>a serial-port style connector or a proper SCSI connector?
>>If the former this is probably the problem. Getting a proper SCSI card
>>will fix it. I recommend Iwill as good value for money.
> Thanks for both responses -- makes sense, not  interpolation but,
> channel bandwidth.
> Seems I was scanning different widths when scanning different images.
> But I still find this odd as I have scsi-2 controller, (Buslogic
> FlashPoint) connected to the older "scsi-1" scanner. It's unfortunate
> and strange that the scanner is faster than the the bus on it...
> apparently.
> More importantly it I've not been able to set the bit depth to greater
> than 8, I think the scanner is rated to 16. There have been times I've
> adjusted xsane settings when the bit depth has gone to 1, and even
> restoring the old settings will not make 8 bit depth available again,
> I have to fix the setting and restart it.
> In the viewer console it says "1 bit/color, 3 colors"  ...I'm don't
> think the image is more than 8 bit but I think is is that many. So I
> seem stuck with 256 colors, what could be wrong? (BTW - this box has
> 1Gb memory)
> // George

Peter Kirchgessner