Noise and sharpening slide scans

[Dread Pirate Roberts]

Is anyone else less than happy with their coolscan?:(

Mine produces unacceptably noisy scans? I don't really think it's just my settings. Compared to my other slide scanner this baby is lower native resolution, appreciably softer, slower and the SF210 needs constant supervision to avoid jamming. I'll admit I do really enjoy sitting back while this machine handles all my loading though instead of doing this manually.

Anyway apart from being less than enthusiastic I've just scanned a bunch of slides for some clients and I don't really want to rescan them. I figured I could get away with post processing in photoshop. However when I try and unsharp mask the scans the noise really gets accentuated. In photoshop I've tried changing the sharpening threshold and it doesn't fix the noise it just makes the unsharp mask less uniform.

I don't think my client would notice their less than perfect but heck I'm a perfectionist at heart and would love to do the best job I can. I'm not about to rescan them though. Oh and before you suggest it multiscanning seams to be a sham, at least it didn't fix this noise for me.

Parameters are:
30 year old Kodachrome slides.
2400 dpi (image 3100 pixels by 2100 pixels)
Running digital ice
No other modifications in scanner (no colour fix, no sharpening, no grain reduct)
Unsharp mask in photoshop only
amount 200
radius 2
threshold 0,1,2 haven't worked.:confused:

Can anyone suggest a viable post process or has anyone else noticed high noise from a coolscan?

[D Thompson]

First off, it seems to me that your USM settings are too high. IMO you need to lower both the amount and radius. You didn't mention whether your shots are landscape or portrait, because I usually use different settings. For landscapes amount of 110-150, radius of .8-1.5, threshold of 0. Portraits get amount of 75-120, radius of .6-1.0, threshold amount of 0-1. These are guidelines and I'd say others may have a different opinion.

If you're in RGB mode then you might try to apply the USM to only the green channel. Typically the red channel contains the contrast, green the detail, and the blue channel the noise.

You could run a reduce noise filter on the blue channel.

Another option is converting to LAB and sharpening just the L channel.

Hope this helps and good luck.

[Dread Pirate Roberts]

Yeah that helped thanks. It didn't make a silk purse out of a sows ear but it's certainly good enough.

A moderate noise filter on the blue channel did knock out enough noise that a moderate sharpen on the green gave an overall pleasant result.

I wasn't dealing with fine art after all but they do represent someones fond memories.

[D Thompson]

Glad it helped.