Removing image grain in post using compositing -- questions

vitamin_D wrote on 12/30/2004, 11:29 AM
Posted this elsewhere, but given the creative types here, I figured someone might be able to help. Thanks if you can...

I've had a pet project for about a year now making a low cost alternative to the P&S Technik devices -- as a group, we're doing these for under $500 (*shhh*)

We've gotten to the point where all but the faintest grain has been removed, and now someone has achieved a breakthrough in removing grain in post. Their method is, loosely:

1. Take your camera with your static mini35 and 35mm lens attached. Make sure your on-camera lens is perfectly focused on the gg.

2. Shoot a well lit piece of paper (a bright gray wall, fridge door, whatever). Make sure the target area is evenly exposed and that the white area fills the frame. If possible, use a monitor (rather than a viewfinder) to judge the lighting conditions. Do not overexpose. Shoot the target out of focus to minimize any detail that it might have. The more out of focus the better. To minimize the camera video noise, do not use gain.

3. Now grab your cam and shoot stuff. Slow pans, out-of-focus shots and hand-held stuff is the best, because that's where the ground glass texture is most evident.

4. Capture all of that into your computer.

5. Import the gg test into your NLE timeline, desaturate it and export a single frame into an uncompressed format like tiff or bitmap. That's your gg noise pattern.

6. Import your test footage (described in p.3) into a software like AfterEffects. Also import the gg test pattern frame, have the software treat it as a clip.

7. Place both items on the timeline, with the gg test pattern as the top layer.

8. Change the gg test pattern transparency mode to 'soft light'.

9. Invert it.

10. Change opacity to 50%.

11. Tweak the opacity level until you are satisfied with the result. It also helps to add a bit of contrast to the grain pattern at this point, but it may not always be necessary.

12. You're done! Export the cleaned up clip into a new file.

My question is, can this technique be achived in Vegas? If so, how?

I've been using the Mask Generator, set to Luminance, with the "invert" box checked, but the results aren't showing themselves. I've even created an inverted grain image in Photoshop, and it hasn't helped.

Perhaps one of the pros here, looking over the technique, could tell me what filters I should look into in order to emulate the "soft light" transparency mode?

Any help would be greatly appreciated...

- jim


No comments yet - be the first to write a comment...