[sane-devel] Scanning with 16 bits color depth (2 bytes/color)

[René Rebe]

Hi,

yes, at least some frontends definitely support this, my avision backend
supports 16 bit channels (including upscaling 10 and 12 bit to 16 bit
for devices which support that) for years.

However, I do not remember which frontends worked well, maybe most
worked to some degree, but IIRC the xscanimage preview had issues
receiving 16bit data, but maybe most other frontends worked fine as
I do not have exceptionally bad memory to this topic :-)

Yours,
  René

Nicolas wrote:
> Ok, thanks a lot for this clarification, I understand that 16 bits per
> color images are supported by the standard, so no special scaling would
> be necessary. 
>
> But do you or someone knows if scanimage or Xsane can handle 16 bits per
> color appropriately ?
>
> Nicolas
>
> Le vendredi 03 octobre 2008 à 08:20 +0900, Olaf Meeuwissen a écrit :
>   
>> Nicolas <nicolas.martin at freesurf.fr> writes:
>>
>>     
>>> So my question is: I know Sane standard defines image format to be RGB,
>>> 8 bits/color.
>>>       
>> Not completely correct.  See below.
>>
>>     
>>> But is it possible to request a Sane frontend to get a 16 bits/color
>>> image format and deal with that, or do I have to transform this 48 bits
>>> image format into 24 bits in the backend, before returning the image
>>> data to the frontend ?
>>>       
>> >From the SANE 1.0 API specification, section 3.2:
>>
>>   A SANE image is a rectangular area. The rectangular area is
>>   subdivided into a number of rows and columns. At the intersection of
>>   each row and column is a quadratic pixel. A pixel consists of one or
>>   more sample values. Each sample value represents one channel (e.g.,
>>   the red channel). Each sample value has a certain bit depth. The bit
>>   depth is fixed for the entire image and can be as small as one
>>   bit. Valid bit depths are 1, 8, or 16 bits per sample. If a device's
>>   natural bit depth is something else, it is up to the driver to scale
>>   the sample values appropriately (e.g., a 4 bit sample could be
>>   scaled by a factor of four to represent a sample value of depth 8).
>>
>> So the answer is yes.
>>
>> Hope this helps,
-- 
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