BCC Match Grain Tutorial

What The?

Why so grainy?  CCDs used in scanners are famous for being noisier in the blue channel when scanning color negative film. This is because the transmittance through the film is lowest in that channel. For an explanation see:

www.aim-dtp.net/aim/technology/sensitometry/

The grainy blue channel is actually a blessing because it provides us with a good reference to match our grain to. If you were not happy with the results yielded by the Sample Controls default settings, you can sample a region yourself.

Sampling Grain for optimal results

8. While still viewing the Blue Channel, move the CTI to a frame where the grain is clearly visible and unobstructed. I chose the 2 second mark of the Timecode (or frame 60).

9. Go to the Sample Frame # parameter and enter frame 60.

10. Go to the Sample Size parameter and double the size to 64.  You now have twice the pixel area to sample from.

11. Go to the Sample Center parameter and click the cross hairs to activate the onscreen controls.

12. Repeatedly click on several areas of the frame until the grain that appears on the sphere is the best match to the grain on the background.  The best results I could get were the Sample Center positioned at X = 339.0 and Y = 129.0, covering an area of 64 pixels (our Sample Size).

13. You can also view your sampled region by changing the View menu to Sample Layer.

above: Sample layer view

« back l next »

• Training Home
• Boris TV
• Tutorials
• Webinar Replays
• Training DVD's
• Training Centers
• Demo Scripts