Neat Image user guide / Key concepts
When it works — types of input images
Neat Image is designed to reduce noise in images produced by digital cameras and scanners, and can also be used to process images from other sources. An input image should satisfy the following requirements:
- Noise must be uniformly distributed throughout the image, i.e., there should be no strong surges of noise intensity in some areas of the image or significant changes of noise characteristics across the image.
Neat Image works fine, for example, on images with high ISO noise. However, 'hot' or 'dead' pixels (produced by single 'broken' elements of image sensor) do not satisfy the uniformity condition and, therefore, are not efficiently removed by Neat Image (hot pixel removal is in our development plans).
Another frequent source of noise is JPEG compression. The JPEG noise is approximately uniform when high quality compression (low compression rate) is used. However, low quality compression makes noise non-uniform. Therefore, we recommend using the highest quality of compression whenever possible. Try to avoid visible artifacts ('squares' or 'blocks' introduced by JPEG compression) in input images beginning from the early stages of image processing! If you can, use lossless file formats such as TIFF or RAW (the latter can be used with the Neat Image plug-in in Photoshop environment).
- Noise should be concentrated in high and medium spatial frequencies. This condition is usually met by images produced by modern digital cameras. This condition may not be completely satisfied if you use the strong (e.g., x2-x3 and more) digital zoom features of digital cameras.