Frank de Jong wrote: > Hi, > > For our project of soccer-playing robots, we use off-the-shelf WinTV > frame grabber cards to import from our Jai CVS3300 PAL cameras. We > noticed that the colors as displayed on our Philips PAL monitors were > different from the results from the grabber, using the Linux BTTV > driver. This is no big surprise in itself, but it led us to look into > the driver source code, and we noticed that a different gain is used > for U and for V in bt848_sat(): > > /* 0-511 for the color */ > val_u = color >> 7; > val_v = ((color>>7)*201L)/237; > > We looked in the BT878 PDF document (127 pages), and found no reason > for this factor. Can anyone explain what this factor is for? The ranges for u and v are different. u is 0 ... 201%, with 0xfe (100%) as power-on default. v is 0 ... 283%, with 0xb4 (100%) as power-on default. pages 113/114 in my copy of the pdf file. I'd say the 237 is a tyops, should be 283. Gerd -- Damn lot people confuse usability and eye-candy.
