# Re: only negative output with scanimage (Canon Canoscan 300)

Denis Prost (denis.prost@wanadoo.fr)
Tue, 25 May 1999 17:47:28 +0200

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Le mar, 25 mai 1999, vous avez écrit :
>-----BEGIN PGP SIGNED MESSAGE-----
>
>
>
>On Fri, 21 May 1999, Andreas Beck wrote:
>
>> > Scan Mode:
>> > (...)
>> > --negative Negatives|Slides [inactive]
>> > Selects the film type, i.e. negatives or slides
>> > (...)
>> > Extra color adjustments:
>> > --negative[=(yes|no)] [yes]
>> > Swap black and white
>>
>> It is a backend bug to have two options with the same name. Maybe we should
>> document that in the SANE specs ... ???
>>
>> Bug the backend maintainer about that. One option should be renamed.
>
>
>Hi. I am the backend author. I hereby consider myself bugged :-) This will
>be corrected in the next version.
>
>Denis: you can try the option "--negative Negatives" or "--negative
>Slides", even if it at first sight does not seem to apply to your scanner.
>Do try both "Negatives" and "Slides" and see which one gives you the
>correct colors.
>
>Another possibility, in case that does not work, would be to specify and
>inverted gamma curve, something like this:
>
> scanimage -d canon:/dev/sgb \
> --custom-gamma=yes \
> --analog-gamma-bind=yes \
> --analog-gamma \
> `perl -p 'for($i=255;$i;$i--){print "$i,"}print 0'`
> --(...other options...)
>
>>
>> > By the way, to temporarily work around this problem, does anyone know a
>> > program that can convert a negative pbm image into a positive one ?
>>
>> pnminvert ?
>>
>
>You can also use:
>
> convert -negate (in the ImageMagick package)
>
Hi Andreas and Manuel,

Thanks a lot for your answers.

"convert -negate" works fine and I'll use it till the next release fixing the
problem.

Cheers,

Denis

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