On 5/31/05, Brad Fuller <[EMAIL PROTECTED]> wrote: > good idea. > But, doesn't this just test the capture ability of the card? > Furthermore, I would expect that a capture via composite and then via RF > would show differences.
Essentially correct -- that is why (sorry, I don't think I explained this well), you use an image editing program to check that the card is capturing the image correctly -- i.e. if the test pattern is supposed to have a 75% saturated red, green, and blue bar, when you load it up in the GIMP and use the eyedropper to select the colour, it should give you 75% saturation, with a hue (er, I think -- sorry, don't know gimp) that is fully red. Of course, you won't get this bangon the first time, which is why you tweak the capture settings a bit to try and get it closer to accurate, then capture the test image again and check the colours in GIMP. Once you know it is capturing correctly, you can output a captured test pattern via your video card and adjust the video card's colour controls until the image displays on the TV the way it is supposed to. (Your DVD should have come with coloured filters you view it through through to adjust the hue -- except, you've already adjusted the TV to the DVD player, so you adjust the video card hue controls until the image that comes out on the TV is correct) To clarify on what I've said above: > Wouldn't you also need to calibrate the output of the card with images > that are known to be correct? > If true, how does one calibrate the input and also the output of video > cards? Yes. Capturing the DVD test pattern, and checking the values in GIMP will tell you whether it is capturing correctly -- once you have the capture settings accurate, you have a known good image that you can output to the video card. There might be differences in the RF input. Of course, there might (will) be differences between between different composite sources. And to make it worse, there will be difference between channels on RF input. But, if you'd like to calibrate the RF input, after you've gotten everything else done, find a channel that runs a test pattern during the night (many local network affiliates will), and capture a test clip -- check the values in GIMP, adjust, rinse, repeat. No, it's not a lot of fun. :) And yes, my description was extremely confusing. Sorry. :( -- Ian Trider [EMAIL PROTECTED] _______________________________________________ mythtv-users mailing list [email protected] http://mythtv.org/cgi-bin/mailman/listinfo/mythtv-users
