[sane-devel] uploading color transformation matrix on HP 4c/3c

[Michal Maruška]

Peter Kirchgessner <peter at kirchgessner.net> writes:

> Hello Michal,
> 
> you need to set mode color to use matrix-rgb. It is not available for
> mode greyscale.

it should be available. Reference manual of HP SCL (v8.0) says:

> on a color scanner, the grayscale data before being modified by the tone map
> is taken from the output of the green channel going through the coefficient
> matrix.

So, where is the problem? 

...so we need to to change just 1 row of the matrix. It would be nice to scan a
color sample (let's say i have hundreds of documents written in red on green
paper), select (in some GUI) the most suitable transformation RGB->greyscale
(as a vector representing it), and then scan in greyscale!



> Please tell me if it works. I never tried that.
i've realized the importance of this matrix just after thousands of scans :(


> Where did you find <pkirchg at aol.com> ? This address is no longer valid.
in sane-backends/backend/hp.README