[sane-devel] terrible (systematically corrupted) jpg at 1200dpi

ken gebser at mousecar.com
Wed Jan 28 18:53:39 UTC 2015

I already opened up a bug report on this: 
https://bugs.launchpad.net/hplip/+bug/1415121, if anyone's interested.

On 01/28/2015 01:44 PM, ken wrote:
> What I wrote already in the prior email makes it clear this is a 1200dpi
> scanner.
> "4 pixels per dot" would correspond to 3 colors + a B/W bit for each
> dot-- what would be required for color scanning at 1200dpi.  "Pixel" is
> a rather slippery term.  Perhaps the tech should have said "sensel". But
> this was tier-one tech support after all, not a developer I was talking
> with.  And she had to look up that much.
> On 01/28/2015 10:33 AM, m. allan noah wrote:
>> "4 pixels per dot" is a meaningless statement. A dot is a pixel. You
>> would have to ask the hplip guys if they can get 1200 dpi out of this
>> scanner.
>> allan
>> On Wed, Jan 28, 2015 at 9:39 AM, ken <gebser at mousecar.com> wrote:
>>> On 01/28/2015 07:23 AM, m. allan noah wrote:
>>>> at least in lineart mode, the scanner maximum is 300dpi. Try scanimage
>>>> --mode=color --help
>>>> allan
>>> According to specifications published by HP, this scanner's hardware and
>>> optical resolution is 1200x1200 dpi.  I just called HP tech support to
>>> confirm this and was told this is correct and that, further, there
>>> are "4
>>> pixels per dot", meaning that the scanner handles both color and B/W
>>> at that
>>> resolution.  So I don't know why scanimage would report that 300dpi
>>> is the
>>> maximum resolution.

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