In StarTools, Histogram Transformation Curves are considered obsolete. AutoDev uses image analysis to achieve better results in a more intuitive way.
When data is acquired, it is recorded in a linear form, corresponding to raw photon counts. To make this data suitable for human consumption, stretching it non-linearly is required.
Historically, simple algorithms were used to emulate the non-linear response of photographic paper by modelling its non-linear transformation curve. Later, in the 1990s because dynamic range in outer space varies greatly, "levels and curves" tools allowed imagers to create custom histogram transformation curves that better matched the object imaged so that the most amount of detail became visible in the stretched image.
Creating these custom curves was a highly laborious and subjective process. And, unfortunately, in many software packages this is still the situation today. The result is almost always sub-optimal dynamic range allocation, leading to detail loss in the shadows (leaving recoverable detail unstretched), shrouding interesting detail in the midtones (by not allocating it enough dynamic range) or blowing out stars (by failing to leave enough dynamic range for the stellar profiles).
StarTools' AutoDev module however uses image analysis to find the optimum custom curve for the characteristics of the data. By actively looking for detail in the image, AutoDev autonomously creates a custom histogram curve that best allocates the available dynamic range to the scene, taking into account all aspects and detail. As a consequence, the need for local HDR manipulation is minimised.
AutoDev is, in fact, so good at its job that it is also one of the most important tools in StarTools for initial data inspection; using AutoDev as one of the first modules on your data will see it bring out problems in the data, such as stacking artefacts, gradients, bias, dust donuts, etc. Upon removal and/or mitigation of these problems, AutoDev may then be used to stretch the cleaned up data.
Back to "Modules"
Image without description
Image "A barely visible nebula, swamped in light pollution and framed by stacking artifacts."