Removing noiseWhen you switch to the Noise filter the program automatically detects the level of noise for your image and corrects it. In most cases this will be enough. But sometimes it is necessary to reduce noise more intensively for some parts. The Hightlights and Shadows sliders and the Equalizer allow reducing noise more intensively only for particular areas of the image - for highlights, for shadows, or for specific colors. These tools are described below.
The noise reduction is similar to blurring and it can result in loosing details. So, you need to find the reasonable balance between the details level and the noise level for your particular image. You can change the parameters of the noise reduction algorithm in order to get better results for your particular image. This makes sense because different images have different noise and detail levels. Hints and TipsNoise reduction is an important step in enhancing images. All the other operations like sharpening and color balancing increase noise and make it more noticeable. It is important to clean the noise from the image at the very beginning. Even bright images shot on a sunny day contain a lot of noise so do not skip this step without a good reason.
Noise LevelThe Noise level slider defines the level of noise reduction for the whole image. The default noise level is detected automatically after you switch to this tab. Noise level is measured in an abstract absolute value from 0 to 200. You can use this value to compare noise levels of different images. ShadowsThe Shadows slider defines the noise reduction level in shadows. If set to 0, it means that the noise reduction level in shadows is the same as in highlights and in midtones. If set to -100%, it means that there is no noise correction in shadows. If set to +100%, it means that the noise reduction level in shadows is twice more intensive (200%) than on the rest of the image. HighlightsIt works the same way as the Shadows slider, but for the highlights. Noise Reduction EqualizerThe equalizer lets you define the noise reduction level for every hue in your image. Usually higher noise reduction levels are set for skin tones and the sky with lower levels set for green.
Use the Noise Map to analyze the changes more precisely. Algorithm parametersRadius - higher values result not only in a cleaner image but also in artifacts on edges. Lower values preserve details but also show more noise. Chroma - defines how much of chromatic noise should be removed. Chromatic noise shows up as points coloured in a complete different way they should be. Noise reduction - defines how much of the luminance noise should be removed. In many cases an image looks more natural if chroma noise is completely removed, but a part of the luminance noise is left. Completely denoised image may look too "plastic". Method allows selecting an algorithm which gives the best results on your particular image. For images with low noise, the "standard" method is good enough, for very noisy images try the"aggressive" method. These methods use completely different algorithms. Noise MapOn the noise map you can see the noise reduction level for different areas of the image. The intensity of the red corresponds to the noise reduction level. You can use this map to check if fine textured areas are not considered to be noisy. It is also a good tool to see the effects of the noise reduction equalizer and the highlights/shadows sliders. Selection BrushThe selection brush selects some area of an image. After you have some selection you can return to the Noise filter and apply any transformation either only to the selection or only to the rest of the image. Learn more about selection brush and it's parameters here. Noise Reduction BrushThe noise reduction brush allows reducing noise only for some parts of the image. For example, you can reduce noise only for faces. Learn more here. |