CaLIGHTs V3.1.9 Released
wols...@gmail.com
Latest Revision 3.1.9.0
StarSatGuard [SSG] has been modified quite a lot. I removed access to the SSG Threshold value. This threshold is now permanently set at 65,534.
I discovered that SSG can be used in tandem with a custom Multiplier to achieve the equivalent of a large histogram stretch which will protect the stars from saturating. The net result is that faint nebulosity in your astrophotos are much brighter and the color of bright stars is retained. The bloating of bright stars is avoided but their halos are brighter. I posted a write-up demonstrating using a 500% stretch of my 2022 Pelican Nebula astrophoto on my website. Click here to have a read.
Image Viewer I added a new option called Show Oval Angle The Show Star Statistics option samples the stars in your astrophoto and calculates HFD[R,G,B], Roundness and Angle. The roundness and angle values relate to the ovality of the stars. There is lots of reasons why stars can be oval. Polar alignment, differential flexure and guiding issues are the most obvious. There are also optical issues including backfocus that can result in oval stars. Low values for roundness typically means a lot of oval stars have been detected. If the star is oval then it makes sense that this oval shape can be at an angle. The Show Oval Angle option uses these angle values to replace the stars with a straight line drawn at an angle that corresponds to the oval angle. The Show Oval Angle option draws three lines (RGB) to indicate the calculated angle for each color channel.
I thought I could use this visualization approach to study backfocus or guiding issues but I’m not convinced it’s useful right now. The angles seem to be pretty much random…which would be expected if there is very little ovality. It may be that the stars need to be significantly oval before the angle values are informative…and I’m just not interested in deliberately creating astrophotos with significantly oval stars J.
