Digital cameras can sometimes struggle to reproduce subject matter that's extremely dark, producing a phenomenon known as ISO noise, named after the equivalent problem on high-speed, or high-ISO, film, where scanners pick up the noise and grain in prints and transparencies shot with film cameras. Either as a standalone application or a plugin, Neat Image reduces this noise without damaging image detail, though you may need to adjust Neat Image's settings if the program changes a color image's brightness.
Luminance Filtration
- Neat Image can process your color photos in YCrCb color spaces as well as in RGB. YCrCb divides color image information into luminance -- brightness or darkness, expressed as "Y" -- along with two channels that divide color into two halves. YCrCb works similarly to Lab color in Adobe Photoshop. When you process images in which the noise appears in the color channels rather than the luminance channel, your image may lighten if you don't turn off luminance filtration.
Viewer Brightness
- When you work on images that fall at the extremes from light to dark, you may want to alter the luminosity of your photo temporarily so you can see noise artifacts more clearly. Neat Image includes viewer brightness controls to help you make these adjustments. These changes don't affect the image itself, just your view of it. You don't need to remove these adjustments before you save your files, but if you forget you applied them, you may lose track of how your image really looks.
Color Management
- If you bring a color photo into Neat Image from a program that doesn't use color management, or one in which you've disabled it, you may see a brightness difference that reflects Neat Image's attempt to manage your unprofiled document. That's because the way image-editing software interprets pixel values varies depending on the color profile you apply, and these variations also affect image brightness. Institute end-to-end color management to eliminate these kinds of surprises.
Other Situations
- When you use Neat Image to counteract noise in images that contain both extremely dark and extremely light areas, you may see a luminance shift if you apply an across-the-board adjustment to the entire image. Instead, concentrate your efforts on the shadow areas in which most of the noise appears, and leave the brighter areas unprocessed. You can limit the luminance range to which Neat Image applies by adjusting the nodes in its noise profile equalizer.
