[sane-devel] High DPi Scan using Ubuntu 18.04.3

[Povilas Kanapickas]

Hi,

On 1/4/20 11:35 PM, r. a. schmied wrote:
> Povilas Kanapickas wrote:
>> Hi,
>>
>> On 1/4/20 7:21 PM, Ralph Little wrote:
>>
>>> Hi,
>>>
>>> On 2020-01-01 11:13 a.m., Sotirios Giavis wrote:
>>>
>>>> I want to scan an area of 50 x 50 mm at 4800 dpi in full-colour 16
>>>> bits.
>>>> This should be possible with Canon Lide 210 but my system won't.
>>>>
>>>
>>> I confirmed the specifications of the scanner that it should indeed be
>>> optically capable of 4800dpi.
>>> I have one of these scanners and I just tried it out. Indeed, in Sane
>>> 1.0.28, 4800dpi is not currently supported and scanning is dropped down
>>> to 2400dpi.
>>>
>>> Looking at the code of the Genesys backend, I see this:
>>>
>>>    model.resolutions = {
>>>        {
>>>            { ScanMethod::FLATBED },
>>>            // BUG: 4800 resolution crashes
>>>            { /*4800,*/ 2400, 1200, 600, /* 400,*/ 300, 150, 100, 75 },
>>>            { /*4800,*/ 2400, 1200, 600, /* 400,*/ 300, 150, 100, 75 },
>>>        }
>>>    };
>>>
>>>
>>> That suggests that it should be supported but is buggy at the moment.
>>> If I have time this weekend, I will look into it.
>>
>>
>> I've already checked this issue and it seems to be some weird
>> interaction within the backend. The high-resolution setting does not
>> just crash, it produces noise. I suspect that somewhere we break the
>> pixel order, but haven't tried to investigate it yet.
>>
>> Regards,
>> Povilas
>>
>>
>>
>>
> Povilas and other interested saners
> 
> using an early 1.0.28 version with hacks for solaris 10; primarily for the
> old old libusb provided with that os, along with a canoscan lide200 all the
> high resolution settings (eg 4800, 2400, 1200) will generate correct 16bit
> .pnm image data if a 16 bit png lib is used and the image display also uses
> the 16 bit png lib.
> 
> in my situation only imagemagic display 7.0.8-29 Q16 sparc 2019-03-04
> correctly displays hi-res 16bit pnm images.  8-bit images of any res
> are no problem with xv, xzgv and display.
> 
> hope this helps with your investigation, but note the lide200 is the
> genesys gl847 stuff and not the gl124 that is used for the lide210.
> 

Yep, LiDE 100 and 200 are the only genesys scanners that can do 4800 dpi
currently.

Regards,
Povilas