[New User] Checkerboard Pattern in Image?

[ecuador]

I was always wondering, how come I don't have to zoom in to 100% all the time like in other image processing software in order to see noise etc?
I guess this explains it You don't see a "pretty picture" fully zoomed out and that's very useful!

[jimv]

The way you're seeing AutoDev rendering your data to the screen is purely because of the way the scaling algorithm (for the purpose of fitting the whole image on the screen) works; it is intentionally coded in such a way that visualisation brings out the patterns by way of aliasing artifacts/patterns (which is what you're looking at), if such patterns are present on a mico-level. It also keeps perceptual noise constant at any zoom factor, rather than smoothing it out when zoomed out. It's a feature, not a bug. It helps to 'unhide' issues with your data that you might have otherwise missed because you were looking at the data on another scale/zoom level.

If you're interested in how this visualisation feature works, here is an explanation; for a Moiré pattern to become visibile, it requires that two patterns are superimposed over eachother. StarTools uses this fact to its advantage by artificially providing the first pattern. If your data - at any scale, zoomed in or not - contains the other pattern required to make up the Moire pattern, the Moiré pattern becomes visible. If there is no pattern in your data, the conditions for a Moiré pattern to become visible are not met and no Moiré pattern will be visible.

Again, look at the data at 100% zoom and you will not see the aliasing pattern (but you should see the artifacts causing the pattern in the first place). Save the image, and it still won't be visible (unless viewed within StarTools or another program that uses intentional nearest neighbour scaling).

Hope this helps.

Thanks for taking the time to explain this highly-informative feature of StarTools! It inadvertently became a useful diagnostic tool.

As for what is causing the excessive mazing/zippering artefacts, I'm not sure. What I can tell you, however is that even if those mazing/zippering artifacts were present in the individual frames, they should've long been stacked out by the stacker. It's almost like we're looking at a single frame here. Are you sure you're not just left with a single frame after rejection?

The persistent checkerboard pattern, presented by StarTools, caused me to reexamine the individual, reconstructed (de-bayered) sub-frames. What I discovered is:

• Images captured with one tool (TheSkyX Professional) can not be correctly reconstructed with any x,y offset combination in either PixInsight or Nebuylosity4.
  Images captured with another tool (Nebulosity4) can be correctly reconstructed in both PixInsight and Nebuylosity4.

Thanks to StarTools for making it so obvious -- once I understood what it was trying to tell me

Of course, with the exception of the recent Nebulosity4 test run, TheSkyX was used for all of my image captures including the ones under discussion in this thread. At this point, I do not know how (or even if it is possible) to salvage the images captured by TheSkyX, and I do not even understand what the issue is with TheSkyX.

[jimv]

Images captured with one tool (TheSkyX Professional) can not be correctly reconstructed with any x,y offset combination in either PixInsight or Nebuylosity4.

As a final followup on this, Terry Platt (Starlight Xpress) has confirmed TheSkyX is introducing a luminance fluctuation (https://groups.yahoo.com/neo/groups/sta ... ges/105977), in the camera data, so he will be contacting Software Bisque (TheSkyX) directly about this.

Thanks again to StarTools for detecting this subtle error.

--jimv

[admin]

Perfect!
Really nice to know that this feature has made a difference in this way.

[TimN]

I had a similar problem with different software. After that, I have always had my capture program (SGP) capture in RAW as well as FITS. If you still have access to the RAW files you are ok.