How to isolate the film grain from a scan

I hope I use the right term "isolate".

 

I have a color negative scan I want to use as a background image. Then I want to add some layers to the image that are shot from the same situation but with a digital camera.

 

My question is, how to dig the original nice film grain from the bacgroud layer and apply it on the entire image. Or is there a way?

Using a film camera, shoot an out-of-focus picture of a plain white wall to produce a blank frame. Then scan the frame at the same resolution as your digital photo and merge them together as layers. You can shoot the wall at different exposures to get different amounts of grain. (With color negative film, underexposure produces more grain; b&w negative film is the opposite.) The important thing is not to have any detail in the blank frame. Set the lens at infinity and shoot close up to throw any wall texture out of focus.

 

If your scanner resolution doesn't match your digital-photo resolution, try up-sampling or down-sampling one of the images to get a match. But resampling the film negative might distort the grain.

 

If you shoot several blank frames at different exposures to produce different amounts of graininess, you can scan and save them for future use with any photos.

Why not just use one of the various digital PS/LR plugins that give you all sorts of simulated film grain. Silver Efex etc etc.? They work very well and you can always fine tune the presets. Tom's plan is OK, but that, presumably, is what these plugins have already accomplished, so you would be duplicating effort, and I bet your home-grown version would not be as successful.

Just use PhotoShop's "add noise" filter on the digital images. You should be able to find a setting that gives a good facsimile of the film grain.

 

Scanned images often don't give a true representation of film grain anyway, due to aliasing effects between the regular pixel spacing and the random scatter of colour film dye globules or B&W silver particles. (In colour film you're not seeing true "grain", but little patches of cyan, yellow and magenta dye.)

 

If the Add Noise filter is too saturated you could create a mid-grey layer and use add noise on that. Then use a suitable blend mode to combine the noise at whatever opacity works best.

Edited March 22, 2017 by rodeo_joe|1

"original nice film grain"

I am quite happy to see that @+#! grain, that I have worked hard to eliminate on my photos, becoming "nice"...