Scanning: Downsampling to reduce grain?

This is not a good way to reduce grain. Use a noise reduction program like NeatImage instead.

The scanned grain is amongst the highest frequency component you have in the image. Down sampling discards this, but does so rather indiscriminately. You will be discarding true image detail as well.

My impression is that the Nikon scanners always scan at 4000ppi, then downsample if you asked for less. So unless you are short of disk space, it makes no sense to scan at less than 4000ppi, since it throws away information that you might find useful later.

I do find that grain is reduced for some films (eg, Fuji Reala 100) if I slightly defocus the scanner. I hit the autofocus button, then manually reduce the focus point (look toward the bottom of the controls on the left side for Nikon Scan) by six units. The "pepper" grain (a result of aliasing?) then goes away, without much loss of real detail.

The Problem is that I don't like noise-reduction programs like NI or Noise-Ninja. Having used them quite often, I don't like the plastic look and the artifacts I often get when using these. Regards Peter

"...I don't like the plastic look and the artifacts I often get when using these."

Much depends on how these are used. For NeatImage, I find it useful to do a couple of things. First, profile each scanned image if possible. Exposure and processing differences change image characteristics that the filtering process seems to care about.

Second, be selective about how much noise to suppress and at what image detail level. In general, I find the default setting a bit overly aggressive. To just suppress film grain, dial down a bit noise suppression for high frequency components; crank the mid and lower frequency filtering limits down much further.

Hi

I recently tried using a bit of gausian blur only in the areas like sky where I'm not losing detail.

for example http://photo.net/photodb/photo?photo_id=6460227 http://photo.net/photodb/photo?photo_id=6459752

I normally find that the "grain" isn't visible in areas of detail so much.

FWIW if as has been suggested downsampling is loosing detail, then defocusing your scanner is gonna do that too.

This image (http://photo.net/photodb/photo?photo_id=6459557) has dreadfully clear grain in my photoshop window, but somehow just doesn't seem to come up so much in lightjet prints ... so maybe its a non issue?

HTH

:-)

Reducing image size and allowing resampling will reduce the appearance of grain (and as others suggested image detail). I don't ever print a file at 100% of a 4000dpi scan as I don't find that it holds up at such an extreme enlargement. There isn't enough image detail there at 4000dpi to use.

I personally use Noise Ninja with conservative settings on higher ISO films and use PhotoKit Sharpener's capture sharpener and output sharpener on my files. I also use a Scanhancer to eliminate Fuji "pepper grain" bubbles which make smooth areas in Fuji slides look rough. You can use an IT8 target to make a preset in Noise Ninja to reduce noise from a type of slide film.

Certain downsampling algorithms produce less grain than others. Lanczos (not available in Photoshop) is particularly good. Bilinear or Nearest-Neighbor are particularly bad. If there is still too much grain/noise, do a slight blur before downsampling. I am fairly sure that you can get better results from Irfanview than from Photoshop.

Try Vuescan's "slight grain reduction" option.

if as has been suggested downsampling is loosing detail, then defocusing your scanner is gonna do that too.

Not necessarily, if the scanner is producing actual aliasing. This would be a result of the scanner's field of view for a pixel being less than the spacing between pixels. Slight defocusing would then have the effect of increasing the effective field of view, and if it was done "just right" wouldn't eliminate real detail (in fact, it would also have the benefit of dealiasing actual details, as well as the grain).

Here's an example of "pepper grain" with a Fuji Reala 100 scanned with a Coolscan V (sorry I don't have an example lying around with higher contrast detail). I'll follow with the defocused version.

Here's the defocused version. I don't see much loss of real detail.

I'd suggest running Neat Ninja rather than doing an indiscriminate gaussian blur before downsampling.

Radford- interesting technique. Looks pretty good, especially for a subject where smoothness is more important than detail (like portrait vs landscape).

A nice non destructive way of doing this that doesn't cost you anything. Dublicate the layer. Than Filter > Highpass (setting of 3 to 6). Change from normal to soft overlay. This is a sharpening trick. NOW inverse that layer and adjust the opacity to the desired look. did this trick to the scan provided by Radford Neal. I think it allows for a touch more control. Also, the wetplate mount does wonders for the 9000.