Guest post by Alia Haley
An image editor often needs to sharpen images in order to reduce the blur, noise and film grain or other unwanted objects in an image. The blur can also be reduced to give strength to an image by sharpening it. Downsampling is one of the simplest procedures for reducing noise. But most of the times some special tools need to be applied and include the following.
The Reduce Noise Filter
It is a good filter tool for the common noise problems, but most of the other third-party plug-in performs better than this tool. The disadvantage with Reduce Noise Filter is that it renders image in a condition where sharpening gets impossible later on.
Advanced Mode Options for reducing noise
Smart Sharpen is useful in film scans, and with its advanced mode option one can control the noise of each selected channels, for example in film scans blue channel has more noise than red and green and selecting the basic button in advanced mode for blue channel applies the effect to all blue film scans while playing them without effecting other things. Advanced mode is useful for color noise reduction, sharpening of details, and the option to remove JPEG Artifact. However all raw images from Camera Raw or Lightroom should be processed for color noise reduction in the processing pipeline. Repeating color noise reduction causes blurring of an image and leads to loss of color in boundaries of that image.
One can easily save the settings of the Reduce Noise filter in the form of presets with names which can be frequently applied in image noise reduction as per requirements.
Strength vs Preserve Details
During normal noise reduction procedures the edge details in an image are generally lost. So it’s suggested to create a pixel layer of the detail and change its opacity after which one can work on noise reduction without affecting the edge details. The edge mask for noise reduction is not inverted as in edge sharpening technique, so the edges show as black and hence are protected from the noise reduction.
The Surface Blur Filter
This filter is used to remove noise instantaneously. The filter works on a radius setting. It is very strong and can quickly turn photographic images into a mess. It needs some fine art skills along with tools like surface mask and opacity after which it can reduce even the most stubborn noise. It’s been found that at 50% opacity and the gentle use of surface blur lessens the strength of the naturally present noise.
Noise Reduction with Despeckle
It is applied to an image copy generally which has a mild-to-moderate luminance noise. The despeckle should be applied differentially to the three different color channels (red, green and blue) with red having least noise and the blue channel with the highest noise. Despeckle is a menu command (Filter > Noise > Despeckle). Overdoing despeckle produces color shifts problem, but it is a very easy tool for sharpening the distorted images.
In very high or low noise situations, many third-parties plug-in are very useful and better than Photoshop plug-ins. Imagenomic’s Noiseware, Visual Infinity’s Grain Surgery, ABSoft’s Neat Image, PictureCode’s Noise Ninja, are very powerful and provide industrial-strength noise reduction.
One important thing to know is that noise can only be reduced but not eliminated otherwise it will destroy the actual image details. Noise reduction should never be done before sharpening unless it is a raw image. Sharpening before reducing the noise worsens and increases the noise. Noise reduction should be performed on layers to protect edges; fine tuning the layer opacity is a skill that needs some practice. One should never overdo the noise reduction. Only disadvantage of using layers is that the files become very large and complex. For that you have to name them in a way that you know it will make sense to you for a long time.
About the author: Alia Haley is a blogger by profession. She loves writing on technology and luxury. Beside this she is fond of gadgets. Recently an article on Reflecting Telescope attracted her attention. These days she is busy in writing an article on Nokia Lumia 800.