On 2017-12-29 at 10:40:46 +0900, Olaf Meeuwissen wrote: > Reinhard Kotucha writes: > > > [...] > > I could probably improve the results if anybody tells me what these > > values mean and how to apply them: > > > > FilmMatR 1.4234 -0.3230 0.0061 -29.7088; > > FilmMatG 0.0600 0.9677 0.0719 -31.3147; > > FilmMatB 0.1562 -0.5104 1.4530 -28.9059; > > I'm not sure about the rightmost column but this is a color correction > matrix. You apply it on the incoming (or gamma corrected?) RGB values > via matrix multiplication like so > > R' = 1.4234 * R + -0.3230 * G + 0.0061 * B + -29.7088 > G' = 0.0600 * R + 0.9677 * G + 0.0719 * B + -31.3147 > B' = 0.1562 * R + -0.5104 * G + 1.4530 * B + -28.9059 > Hi Olaf, thanks for the hint. I assumed something like this but was confused by the fourth column.
I wrote a Lua script which allows me to modify each pixel within a PNM file. I first applied the lookup-table (sensor specific) and then the matrix (film material specific). It seems that colors are correct now. When I apply the matrix first, colors are completely wrong. I don't know whether the range of values in the fourth column is [0..255] or [0..99]. Since there is no significant difference between these values (all values are abt. -30), it's nearly impossible to determine visually which range is correct. I assumed [0..255]. The pictures can still be improved with an external tool like ImageMagick. They look better with increased values of brightness and contrast, at least on screen. Thanks again, Reinhard -- ------------------------------------------------------------------ Reinhard Kotucha Phone: +49-511-3373112 Marschnerstr. 25 D-30167 Hannover mailto:reinhard.kotu...@web.de ------------------------------------------------------------------ -- sane-devel mailing list: sane-devel@lists.alioth.debian.org http://lists.alioth.debian.org/cgi-bin/mailman/listinfo/sane-devel Unsubscribe: Send mail with subject "unsubscribe your_password" to sane-devel-requ...@lists.alioth.debian.org