Adding narrowband accents to visual spectrum datasets has traditionally been a daunting, difficult and laborious process, involving multiple workflows. The NBAccent module is a powerful module that starts its work as soon as your load your data in the Compose module. Crucially it adds only a single, easy step to an otherwise standard workflow, while yielding superior results in terms of color fidelity/preservation.
By making narrowband accents an integral part of the complete workflow and signal path, results are replicable, predictable and fully tracked by StarTools' unique signal evolution Tracking engine, yielding perfect noise reduction every time.
Activating the NBAccent module functionality, starts with importing a suitable narrowband dataset via the Compose module. The Compose module will extract the relevant channels from the dataset you give it, as directed by its 'NB Accents Type' parameter.
The narrowband dataset is processed in parallel during your workflow; the Bin, Crop, Mirror, Rotate and - most notably - Wipe modules all operate on the narrowband accent dataset in parallel as you process the main luminance (and optionally chrominance) signal.
There are many different ways and techniques of incorporating narrowband data into your workflow. Which method is suitable or desirable, depends on the object, the availability of datasets/bands, and the quality of those available dataset.
The NBAccent module was specifically designed for the most difficult compositing use case; that of using narrowband as means to accentuate detail in a visual spectrum 'master' dataset. In other words, in this use case, the narrowband is used to support, enhance and accentuate small(er) aspects of the final image, rather than as a basis for the initial signal luminance/detail or chrominance/coloring itself. This is a subtle, but tremendously important and consequential distinction.
As such, the narrowband accent dataset is processed entirely independent of the luminance and chrominance signal of the 'master' dataset; it sole purpose is to accentuate detail from the 'master' (luminance/chrominance) dataset through careful - but deliberate - local brightness and/or color manipulation.
If you wish to use the narrowband signal as luminance or chrominance itself, rather than for accentuating luminance or chrominance, then the NBAccent module will not apply, and you should use the Compose module to load your narrowband as luminance and/or chrominance instead.
Given the module's use case, it is best invoked late in the processing flow, after the Color module.
Examples of use cases for the NBAccent module are;
Ideal datasets for augmenting visual spectrum (mono or colour) datasets are Ha datasets, O-III datasets, Ha+O-III datasets or datasets from the popular duo/tri/quadband filters for OSCs and DSLRs such as the Optolong L-Extreme, the STC Duo , the ZWO Duo-Band and other similar filters with narrow spectrum responses.
The first screen allows you to fine control which areas will receive narrowband enhancement. The procedure and, hence, interface is closely related to the AutoDev module. Familiarizing with AutoDev is key to achieving good results with StarTools, and being able to use it effectively is a prerequisite to being able to use the NBAccent module.
One notable difference compared to AutoDev, is the way the stretched narrowband data is presented; areas that will not be considered for the final composite, will be clipped to black. Areas that will be considered in the final composite, will appear sretched as normal. The other difference from the AutoDev module, is the removal of the 'Detector Gamma' parameter and its replacement by the 'Threshold' parameter; this parameter allows for intentional clipping of the narrowband image, for example to avoid any background imperfections being added to the final composite. It is important to note that this parameter should be used as a last resort only (for example if the narrowband accent data is of exceedingly poor quality) as it is a very crude tool that will inevitably destroy faint signal.
It is important to understand that the signal as show during this first stage, is merely signal that is up for consideration by the second stage. Its inclusion is still contingent on other parameters and filters in the second stage. In other words, during this first stage, you should merely ensure that, whichever signal is visible, is actual useful narrowband signal, and not the result of background imperfections or other artificial sources.
For your convenience, the NBAccent module will, by default, use the same Region of Interest that was specified during AutoDev.
The second stage is all about using the signal from the first stage in a manner you find aesthetically pleasing.
Straight up, there are two presets that are useful in two of the NBAccent's major use cases;
These presets dial in the most useful settings for these two usecases.
The 'Response Simulation' parameter is responsible for the visual spectrum coloring equivalent that is synthesised from the narrowband data. The NBAccent module was designed to synthesise plausible visual spectrum coloring for a wide range of scenarios and filters;
The 'Luminance Modify' and 'Color Modify' parameters, precisely control how much the module is allowed to modify of the visual spectrum image's luminance/detail and colour respectively. For example, by setting 'Luminance Modify' to 0%, and leaving 'Color Modify' at 100%, only the colouring will be modified, but the narrowband accent data will not (perceptually) influence the brightness of any pixels of the final image. Conversely, by setting 'Color Modify' to 0% and 'Luminance Modify' to 100%, the narrowband accent data will significantly brighten the image in areas of strong narrowband emissions, however the colouring will remain (perceptually) the same as the visual spectrum input image.
StarTools is a new type of image processing application for astrophotography that tracks signal and noise propagation as you process.
And all this is just what Tracking does for the deconvolution module.
The 'Context Size' parameter controls the upper size of the detail/structures that may provide context for smaller detail.
The noise signature of the deliberately left-in noise, is precisely shaped to be aesthetically pleasing for precisely this purpose.
Next click a few times on different parts of the purple or blue halos and they will slowly disappear with each click.
You can convert everything you see to a format you find convenient. Give it a try!