[sane-devel] pixels_per_line and bytes_per_line

[m. allan noah]

On Tue, 25 Apr 2006, Henning Meier-Geinitz wrote:

> Hi,
>
> On 2006-04-25 14:31, Wittawat Yamwong wrote:
>> The SANE Standard Version 1.04 under 4.3.8 states that
>>
>> c >= B * n * d/8    for d > 1
>>
>> "Note that the number of bytes per line can be larger than the minimum
>> value imposed by the right side of this equation.  A frontend must be
>> able to properly cope with such "padded" image formats."
>
> The frontend should be able, but in reality it isn't. At least I don't
> know of any frontend who could do that. You can also test that
> behaviour with the test backend by setting the option --ppl-loss to a
> value > 0.
>
>> doesn't need to throw the padding bytes away. But the output image from
>> "scanimage" is corrupted. It seems to me that the frontend works properly if
>> and only if c = B*n*d/8. What should I do in this case?
>
> Fix scanimage and all the other frontends. Or easier, do the removal
> of the padding in the backend.

the other option in this case is to change the image size as reported to 
the frontend by the sane_get_param call, so that it is a multiple of 12. 
several backends do this with binary scans that must be on 8 bit 
boundaries.

allan

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