How to avoid sharpening grain?

[cmox]

There is one question that always comes to my mind when I edit my scans in Photoshop: where is the secret setting that allows sharpening the image and not the grain? For Photoshop, there is no difference between an edge and the countour of grain, no matter how I set the USM dialog. Any ideas how not to emphasize grain when sharpening?

[Walt Calahan]

Look up sharpening using the 'High Pass' filter. This sharpens the outline of objects but not the grain.

Make a duplicate layer of the image. Apply the 'High Pass' filter, set at 1.5 or 2.0. Then convert the layer to soft light, or hard light, depending on the look you are after. Then flatten the effect into the duplicate layer. Once there, you can change to percentage of the effect from 0% to 100%, to soften the effect some more.

Once you like what you have, then flatten the duplicate layer into the original.

As with all sharpening, you do this at 100% viewing, and the very last correction to the image before printing.

How this is helpful. If my instructions are not as clear as then could be, I suggestion looking up sharpening with 'High Pass' filter on-line.

[cmox]

Walter, I tried it... but actually I don't see much difference between the results of plain unsharp masking and this method. In order to decrease grain I have to decrease the whole effect which comes close to decreasing unsharp masking... maybe I have to try more, but this first run did not work. I also tried different layers with different sharpening settings and hard/soft light and different percentage... but it's not better. The basic problem is that Photoshop does not have the ability to diffentiate between noise/grain and details. I really consider buying a noise reduction tool to eliminate graininess before sharpening.

[keithwms]

What kind of image is it? Colour? B&w? Was it scanned?

[cmox]

I have different sorts, but they are all BW and scanned on an Imacon 646 at highest resultion, no sharpening etc. applied. The images range from 35mm Tri-X at 1600 ASA up to 6x7cm on Tmax 100 and Acros.

[keithwms]

Oh okay. I ask because there is some issue of grain being less prominent if the neg is wet scanned. I haven't played with it much myself but that is something you might consider- trying to get less grain in your scan, for starters. I'm not familiar with the imacon but I assume that it scans dry. A true drum scanner will of course scan wet (with oil) and there are a number of flatbeds that also allow you to scan wet. Also, I guess the imacons don't allow ICE.

I mention all this because perhaps you are getting more grain into your scan than is necessary.

The other thing to consider is whether to develop in pyro, if optimal scanning is your aim. I think there are some good arguments for that, but I am new to it so I won't speculate. Others here can comment or you can search around here and find informative comments. As I recall the main advantage is that the grain is more apparent in one channel so you can address it separately from the lower frequency image detail.... but again I must confess complete ignorance of this technique at this point, I just got started with pyro last week.

[Donsta]

My personal opinion is that wet scanning does not make a huge difference to grain being visible in scans - in my experience, it usually results in slightly higher local contrast and perhaps a touch more acuity, but no less grain. A drum scan with a variable aperture has a very big advantage because you can "mask" a lot of the grain effect with over sampling at a larger aperture.

On a CCD scanner, definitely scan in RGB and you will most likely find the green channel to be the cleanest. There's no easy answer to the question though. The Smart Sharpen function followed by a bit of noise reduction can go a fair way to tighten up edges without exaggerating grain. Most important is to make a test print at final size before you decide that you have a visible grain "problem". Keith's suggestion of a pyro developer is a good one - most pyro developers' stains do help to mask grain in the dense areas of the negative (highlights of the print) where the grain is most visible.

[bob carnie]

You may want to look into Adobe Lightroom.
In the sharpening area of Develop moduale. the last three functions are cool. by holding down option key while moving the slider you will see only a BW image showing the key areas of the image, the more you move the slider obviously the stronger the effect. The last slider is masking which is really impressive, as it will block out much like a rubylith of old days, areas of the image,, smooth skin, smooth skys , and allow you to only sharpen detail areas like edges of buildings, eyes, eye lashes, hair, .
I think this has distinct advantages as a second selective sharpening feature.

[sanking]

There is one question that always comes to my mind when I edit my scans in Photoshop: where is the secret setting that allows sharpening the image and not the grain? For Photoshop, there is no difference between an edge and the countour of grain, no matter how I set the USM dialog. Any ideas how not to emphasize grain when sharpening?

Look into a program like Neat Image or Noise Ninja. They will allow you to sharpen the image but not the grain, within reason. You could do this yourself with Photoshop but NI and NN will allow you to quickly try out various combinations to achieve the effect you want.

Sandy King

[Ben Altman]

There is one question that always comes to my mind when I edit my scans in Photoshop: where is the secret setting that allows sharpening the image and not the grain? For Photoshop, there is no difference between an edge and the countour of grain, no matter how I set the USM dialog. Any ideas how not to emphasize grain when sharpening?

I've played with routine that reduces the bright halo caused at edges by sharpening, while leaving the dark halo unchanged. This is not specifically aimed at grain, but it may help. I'm sure savvier folks than I could improve on the concept.

I duplicate the file and sharpen both the original and the duplicate, using identical settings. On the duplicate, I use Fade Unsharp Mask (100%), set to Darken mode. I then use Apply Image, again in Darken mode, to impose the duplicate image onto the original. Varying the amount gives control over how much effect you get. I usually use between 40% and 60%. The final image ends up slightly darker-looking than the unsharpened image.

Have fun!

Ben