Hello Michal, Michal Marus(ka wrote:
> Peter Kirchgessner <[email protected]> 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? > I am talking about the hp-backend of SANE. Some options are only active under certain conditions. When I had a look at the backend, it seemed to me that option --matrix-rgb is only active when --mode Color is selected. But that is not true. If you want to use the --matrix-rgb, you need to rebuild SANE (or at least the hp-backend) from source. You need to modify hp.h: Change line #define ENABLE_10BIT_MATRIXES to #undef ENABLE_10BIT_MATRIXES Change line #undef ENABLE_CUSTOM_MATRIX to #define ENABLE_CUSTOM_MATRIX After these changes rebuild SANE (be sure to remove all hp*o from the backend's directory). Now the option --matrix-type has a new choice "Custom". You need to use it along with --matrix-rgb: scanimage -d hp:/dev/sg0 --mode Grayscale --matrix-type Custom --matrix-rgb 1.98,1.98,1.98,0,0,0,0,0,0 > scan.ppm This creates a grayscale scan where the data represents the data from the red channel. > ...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! > > You can start xscanimage and switch to matrix-type Custom. Then you see what is used to enter the values for matrix-rgb. This was the reason why custom matrix has been disabled. Using 9 sliders would be an alternative. > > >>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 <[email protected]> ? This address is no longer valid. >> > in sane-backends/backend/hp.README > > I see. At that place it is ok. --Peter -- Peter Kirchgessner http://www.kirchgessner.net mailto:[email protected]
