2003-09-28

Neat Image is one of the best image noise reducing programs currently available. It is available as a Photoshop plug-in and a standalone program. Its greatest strength is that it works from noise profiles, which are files that define "what noise is". Every imaging system, whether a camera or scanner, has its own unique noise characteristics, so removing noise from a Canon EOS-1Ds DSLR with a noise profile from a Nikon Coolpix 5000 is going to unnecessarily strip out a lot of detail in the 1Ds image, because the Coolpix has a much higher noise level than the 1Ds. So profiles are a good thing, but making a good profile can be a real hassle. You need to select an area of a photo devoid of detail, like an open patch of sky, and tell NeatImage that any detail in that area is noise, and image elements of that type should be removed from the entire image. Or you can use Auto Fine Tune, which scans the entire image, but can be fooled if most of the image has similar fine detail, like a photo of a rock wall.

I created a series of noise profiles for the Canon EOS-1Ds, using the following methodology:

I attached a Color Checker to the wall, and put my 1Ds camera on a tripod in AV mode to get this:

I deliberately misfocused the camera, so that the only fine detail in the image is noise, shot a test frame of a white card and set a custom white balance, then shot a series of frames at every ISO setting the 1Ds offers (50-1250). in RAW + Large JPEG mode. As you can see, the exposure settings I used yielded a nice balance between the highlights and shadows, and a fairly even distribution of image data from light to dark. This is the ideal condition for Auto Fine Tune to make the most accurate noise profile--there is no fine detail in the image except noise, and the colored blocks cover all the major color groups and brightness levels.

The JPEG settings I used were Large/Fine (4064x2704), quality 8, matrix 1, all other settings camera default.

1Ds JPEG Noise Profiles (203K ZIP file)

The RAW files were converted with Adobe Camera RAW/Photoshop 7.0.1 with the following settings: white balance "as shot", exposure 0, shadows 0, brightness 50, contrast +50, saturation 0, sharpness 0, smoothness 5, 16 bit Adobe RGB. Changing these settings (especially exposure, sharpness, and smoothing) will change the characteristics of the noise dramatically, and render the noise profiles much less useful. These profiles will also not work very well with the output of other RAW converters such as File Viewer Utility or Capture One.

1Ds ACR 7 Noise Profiles (203K ZIP file)