Quick start guide 2 - stream preview and analysisWhen a planet shape can be detected in the ROI, the main window of the PEAAnuts plugin shows the extracted section from the ROI with the planet in center. The preview window size must be adjusted manually via the drop down list.![]() Planet detection is controlled by the low detection threshold in the stream options. Choose a reasonably low value such that the full shape is recorded, but keep it sufficiently above the noise and background level such that detection runs reliably even when circumstances vary a bit. The default setting usually is OK for nighttime applications. For daytime recordings or otherwise low contrast situations, adjustment is necessary. The high threshold value is not important for detection, but has a meaning for the stream analysis (see below). Stream analysis and focus aidIn the plguin, always a handful of frames gets accumulated on the fly, to reduce pixel noise, then these mini stacks are evaluated in order to produce some data which can be helpful for focusing. A graph below the image shows the cross section intensity curve. 5 Parameters are derived from this curve:
The interpretation of the data as focus aid is simple. The smaller the detection diameter or the isoline distances, the better the focus. For the slopes and the high threshold diameter, it is just opposite. Slopes and/or high detection diameter (with a suitable threshold) seem to be most useful in practice. But everyone is encouraged to find out the best way for using one or more of these data. Pre-stackingFor reducing noise, a minimal pre stacking is done both for the live stacking and the stream preview. In the bottom left two drop down boxes are located. PA and SPV.PA means the number of frames which will be added up before sending them to the live stacking module. Of course, to freeze seeing, one aims at minimizing exposure times, so pre stacking should be kept at a small amount, otherwise it counter-acts the whole idea. But a mimimum avaraging is helpful for all the following process steps, and, of course, to reduce noise. SPV is a multiplier, it specifies the number of PA sets added up for the stream preview. For the stream preview, a higher level of averaging helps to reduce flickering of the displayed analysis data. The default settings (PA = 2 and SPV = 3) mean always 2 frames get averaged for live stacking, and 6 frames get averaged for stream preview. Especially in cases with bad seeing and/or high gain settings, increasing the SPV multiplier is reccomended to calm down the data jittering. Isoline displayApart from the internally calculated isoline distance on the cross section line mentioned above, isoline display can be activated for the whole preview image. In color mode, a special red/blue isoline pattern can help in ADC tuning.Consult the chapter Stream analysis for further details. |