THE EFFECTS OF NIKON SCAN'S ICE SETTINGS

ICE is an extremely useful utility that digitally removes dust and scratches from your scans by using infrared light. It works because IR light passes through (most) films unaffected but is obstructed by dust and scratches. Using this principle, a pre-scan using IR light can be used to map out the dust and scratches and post-processing then used to correct for it. There is however a slight amount of sharpness loss due to this process and the following test focuses on examining to what degree the different ICE settings in Nikon Scan 3.1 reduce this sharpness.

The methodology used involves scanning the same slide three times in 14 bit mode, at 4000 dpi, and in sRGB color space using a Nikon Super Coolscan 4000. One scan is made with ICE off, one with ICE set to "Normal", and one scan with ICE set to "Fine". The images are then cropped to "actual pixels" size, converted to 8 bit color depth, and saved out as high quality (Q=90) jpgs in Photoshop to make them viewable on the web. This system is not perfect due to the compression of the images and other factors but I believe it accurately shows the effects of the different ICE settings.

In these images, we can see that the loss in sharpness from using ICE set at the "Normal" setting is very slight but markedly more noticeable at the "Fine" setting. Both settings are equally effective at removing dust and scratches in this example but with heavily scratched film, the "Fine" setting will be notably more effective.

CONCLUSION: Because even "clean" film will often show signs of dust and scratches when scanned and because the "Normal" setting only very slightly reduces sharpness, setting ICE to "Normal" as the default scan setting is recommended.