Digital Home Thoughts: Noise Ninja Photoshop Plugin (Beta 4b)

Patterns and Profiles
Digital noise typically occurs in some sort of predictable pattern based on camera brand and model. It is possible to profile your camera to get a baseline for the pattern of noise. Noise Ninja can use this baseline profile to remove noise while retaining detail and sharpness in the picture. There are many profiles available for download on the Noise Ninja product site.

The ISO setting on a digital camera is roughly equivalent to the ISO rating of film. Higher ISO film is also referred to as "fast" because it allows you to use a faster shutter speed to capture action in darker settings. A higher ISO number in digital photography will have the same effect, however, in exchange for shooting in low light, higher ISO values tend to introduce more digital noise.

Since the pattern of noise can vary at different ISO settings there is a noise profile for each ISO setting per camera model. When working with an image, you can look at the EXIF data to determine what the ISO value is for that image and then choose the correct profile accordingly. Noise Ninja can also read the EXIF data and load an appropriate profile based on the ISO setting and camera model (note: this feature has not been implemented in the current plugin beta)


Figure 1: The ISO Speed Rating can be found by looking at the EXIF data for an image.

Noise Ninja also has an automatic profiler which can be used if there is not an existing profile for your camera. The auto profiler attempts to find uniform areas with little detail to create a profile for the noise in the rest of the image. The documentation states that the auto profiler can be confused by certain textures and that using a preset profile or manual profile can be more effective. The automatic profiler in the plugin has been improved over the stand alone product. These improvements will be merged back into the stand alone product in a future release. For my uses so far, I've found the automatic profiler does a good job with my test images.

For a finer degree of control, there is an option to set up a manual profile. Creating a manual profile is as simple as drawing rectangles over the image preview. Each rectangle area is examined by the program and used to create the profile. The documentation suggests highlighting areas that are similar in color and tone. The manual profile tool can also be used to enhance the results of the auto profiler.