- Post
- #562620
- Topic
- Laserdisc players - screenshot comparison
- Link
- https://originaltrilogy.com/post/id/562620/action/topic#562620
- Time
OK, so who remembers this thread?
I've recently revisited this test pattern again. Here it is again, after a multi-frame average and black and white levels corrected in Avisynth:
Now, from reading up about the components of this pattern, I believe the background is supposed to be a 50% grey. This background is too bright. Since the black and white points are correct, we'll use a gamma adjustment to darken it:
The grey bars above the colour bars end up being approx 75% after this adjustment - this is what they're supposed to be. This is to match the intensity of the colour bars as a reference. This works as follows: let's convert to RGB and show just the blue channel:
If everything was calibrated correctly, the colour bars would alternate black-blue; the blue bars would be the same intensity as the bars above and the blacks would be pure black. Now you see that some of the blacks have a little blue in them, and the blue bars are darker than the bars above. The first problem is fixed with a minor hue tweak, the second by a little saturation boost, now we get:
Not perfect, but pretty close. You can check the red and green channels too, if you wanted. So what effect does these further tweaks have on the final image?
There you have it - capture calibration complete!