Author Topic: Blink Problem !  (Read 390 times)

Offline pscammp

  • PixInsight Addict
  • ***
  • Posts: 115
    • View Profile
Blink Problem !
« on: 2018 February 10 04:39:23 »
Hello all,
    When I use Blink and load all the images from 'X' folder for viewing it defaults to using a STF with linked colour channels, I click the button to unlink
the channels and then I can view the images without the red colour bias my Camera produces (non calibrated Lights used here).

When I step through the images one by one they get darker and darker until it looks like no STF is applied at all. As soon as it comes back to image one
I get full STF again only for the images to darken again as I step through them.

It does this with all the sets of lights I have got so it's not just a particular set of lights being affected.

If I click the button in Blink to apply an actual stretch rather than the STF then all the images look the same brightness as I step through them.

Does anyone know what is happening here, does anyone get the same issue  ????

Many Thanks

Offline bulrichl

  • PixInsight Old Hand
  • ****
  • Posts: 441
    • View Profile
Re: Blink Problem !
« Reply #1 on: 2018 February 10 05:44:03 »
Same here. You can toggle the behavior of Blink by selecting either 1) the first  or 2) the second pictogram from top:
1) computes the optimal stretch for each individual image, so the overall brightness of the images will be equal. With this setting you can visually discern large differences in the SNR of the frames.
2) computes the optimal stretch for the current images, and applies this (same) stretch to ALL images, so the overall brightness of the presented images will reflect the changing background levels of the images.

In this post I provided SNR and Median (the output of Subframe Selector) of images of some different nights. Taking a look at the Median (red curves), one can easily see the effect of light pollution at low elevation in the southeast at the beginning of the imaging. The LP increases the background level. As the target moves away from the affected sky region, the effect vanishes. Maybe you have a similar situation?