Anyone who works with images, sooner or later has to deal with noise. Any natural images (that is, others than drawings or rendered images) always contain some noise. The noise may have different intensity, pattern, nature, and structure. And you always have to keep it in check.
Frankly speaking, so far there is no unified approach or perfect solution for the noise problem. No one can give you the magic bullet. Even if someone offers you a “perfect” solution, you should know that it’s impossible to remove noise without any loss. All noise reduction algorithms have two major side effects: the loss of detail and the introduction of artifacts.
The first side effect cannot be completely eliminated, you always have to trade off between the loss of detail and noise. Noise masks small details, that is, useful information. Noise can be of different nature, so useful information is masked by and mixed with noise. When you remove the noise, you always reduce the amount of useful information.
The second side effect of noise reduction is the introduction of artifacts. Depending on the algorithm used, they may manifest themselves as rings, “accordion,” squares, etc. This effect is pretty unpleasant. It has a very bad impact on image perception by the viewer, mostly because such artifacts are too “geometrical,” that is, unnatural. Because such regularly-shaped elements do not occur in the natural environment, the viewer subconsciously rejects them.
As you can see, our goal is to minimize both the loss of detail and the introduction of unwanted artifacts. The SightLine plugin solves the first problem by allowing the user to finely control the noise reduction process by tuning the noise reduction level in a wide range of spatial frequencies, and by dividing the image into channels in the Lch color space (for more details, see the FAQ).
SightLine tackles the artifacts problem by changing their nature. The resulting artifacts will be more natural, so it is less likely that the viewer will subconsciously reject them.
In addition to noise reduction, there is another goal: to increase the image detail. The semipolar method called “sharpen” is mostly used for that end. We have added it to our plugin.
Surely, this method cannot restore any lost detail (that is, recover lost information). However, it allows you to emphasize what is left. Oftentimes, using this method is sufficient to improve the visual perception of an image. Of course, you can use the Sharp module separately, without attempting to reduce the noise when it is imperceptible.
Just like in the Noise Reduction module, you can finely control the sharpening in a wide range of spatial frequencies and in each Lch channel. In addition to sharpening, this module includes a feature with the opposite effect, blur. You can say that blur is an “inverted” method, because it smoothens the image detail (that is, reduces the amount of spatial information). You can always choose what you prefer to do: to sharpen the image, or to blur it.
The bottom line is that our solution is not perfect: We provide a flexible tool that allows you to fully control both the noise reduction process and the amount of image detail left.
Before installing SightLine, please verify that your hardware and software meet or exceed the minimum system requirements.
Windows 7 x64 or higher
1 GB free RAM
100 MB free disk space
1920x1080 screen resolution
Adobe Photoshop CS4 (x64) or higher
Mac OS X:
Mac OS X 10.8.5 or higher
1 GB free RAM
100 MB free disk space
1920x1080 screen resolution
Adobe Photoshop CS5 (x64) or higher
Installing SightLine on Windows. Run SightLine.exe and follow the installation wizard:
Installing SightLine on Mac OS X. Run SightLine.mpkg and follow the installation wizard:
Important Note! If you are installing SightLine on Mac OS X, do not change the location of the plugin’s folder. Otherwise, the licensing system will be unable to work, which will prevent you from using SightLine. The "/Nuclear Light" folder containing the plugin must be located in the standard applications folder ("/Applications").
Also check the installed plugin’s properties so that the required access privileges are provided.
Put your license file into the installation folder. If you have Windows, the default folder is "\Program Files\Nuclear Light\SightLine" (unless you’ve specified a different folder when installing the plugin). If you have Mac OS X, the folder should be "/Applications/Nuclear Light". If the license is valid and you did everything right, you can start using SightLine.
You can find the plugin in the Adobe Photoshop filters menu: Filter -> Nuclear Light -> SightLine
SightLine works with the input image in the RGB/Lab color spaces; internally, the plugin uses the Lch color space. If your input image is in CMYK, you can avoid any tiresome conversions to Lab/RGB by using smart objects.
Just convert the layer of interest to a smart object, open it, convert it to Lab or RGB, use SightLine, and save the changes. If you want to do nondestructive editing, that is, you might need to make corrections at any moment, simply convert the layer inside the smart object into another smart object, and apply SightLine. After that, you can open that smart object again to make changes.
Smart objects are Adobe Photoshop’s standard feature, and we’ve just showed you some tips and tricks.
As usually, we recommend using the 16-bits-per-channel mode. In some cases, it will help you minimize the posterization effect. Even though SightLine internally handles floating point numbers, the 16-bits-per-channel mode eventually produces a better result compared to the 8-bits-per-channel mode.
SightLine does not impose any limits on image size. It can handle even huge images. The only limit is imposed by Adobe Photoshop and by your computer’s performance. At the moment, the maximum image size supported by Adobe Photoshop is 300,000 by 300,000 pixels.
As SightLine pretty intensively uses memory, we recommend that you have at least 16 GB of RAM. We also recommend that you have a multi-core CPU, which will be efficiently used by the plugin.
SightLine’s user interface consists of a few panels (windows).
The first one is the Preview panel:
The second one is the Tools panel:
Let’s take a closer look at these panels.
In the bottom of the Preview panel, you can see the control buttons:
The buttons have the following functions:
Shortcut keys and mouse actions for quick access to functions are displayed in square brackets and separated by a comma. The first value of the modifying key is for Windows, and the second one (after the slash) is for Mac OS. Below you can find similar quick-access functions.
You can move the preview image with [Mouse Left Button] as indicated by the open-hand mouse pointer.
Note: To get a good result when applying the plugin to the preview image, always set the scale to 100%. Otherwise the algorithm will process the scaled preview image, not the whole image. We did it just to speed up the processing of the preview, so that using the plugin is more comfortable.
Now take a look at the Tools panel. At the top, you can see some status indicators and information signs:
Now take a look at the plugin’s main tools.
There are two modules:
The orange color in the tab title indicates that the tool is in use, and that it has been used to do some corrections.
The Noise Reduction module looks like this:
It consists of:
The Noise Reduction module allows you to apply different noise reduction levels for different spatial frequencies. The highest frequencies are at the left, and the lowest ones are at the right:
All frequencies are divided into four main frequency groups. Each group consists of three subfrequencies (fractional octaves). This way, you have a finer control over the noise reduction level within each group.
You can change the noise reduction level in a frequency band by dragging the slider with [Left Mouse Button]. For a more accurate, smoother change of the noise reduction level, hold the [Shift] key and move the slider with [Left Mouse Button]. To reset the level slider to its initial state, use the combination [Ctrl/Command] + [Left Mouse Button Click] on it.
You can apply the Noise Reduction module to each Lch channel. That’s why it is available on each of these three tabs: Lightness, Chroma, and Hue. The principle of operation and controls are the same for each channel.
The image detail control module looks as follows:
It consists of:
The principle of operation of the image detail control module is similar to that of the Noise Reduction module, except for the frequency band level sliders, which can be negative or positive.
Positive values mean increased detail (sharpen), and negative values mean reduced detail (blur).
The frequency division principle is different, too. Unlike in the Noise Reduction module, in this module, frequencies are distributed without dividing them into octaves. You can use the frequency separation factor slider (6) to control the frequency separation width. The more the value, the farther are the frequency bands from each other. This way, you can change the frequency range by making low frequencies even lower.
The total level multiplier increases the sharp/blur effect, depending on the level value in the frequency band. That is, if the level value is positive (sharpen) in a band, the effect will be increased; if the level value is negative (blur), the effect will be increased, too.
Just like in the Noise Reduction module, the image detail control module works with all three Lch channels.
So far, our image noise reduction solution is far from perfect, but are working hard to improve our algorithms. Hopefully, our plugin will help you to keep noise in check.
If you have any questions on using SightLine, our technical support team will be happy to provide the answers.
Enjoy using our product!