Superbias image

[astropixel]

Out of interest I reprocessed this widefield using a SuperBias. No darks. Bias and flats only. Light frames 46 x 2.5 minutes.

I didn't go to a lot of trouble with the colour.

The original master bias = 42 frames

Finished up with MultiscaleMedianTransform, which smoothed out the background considerably. This is probably best applied after the first histogram stretch.

Certainly different. The background looks smoother, but a little pixely. More data might fix this.

Is this the type of result to expect. BTW sampling down produces a patchwork look.

[Nocturnal]

I see some kind of checker pattern. Is that also present in the 1:1 image?

[cs_pixinsight]

I see the same pattern.  Kind of like a screen over a window.  Can you post a 1:1 crop for a closer look?

[astropixel]

The chequer pattern is not as evident 1:1, in-fact it is very smooth - more pixely, particularly in dark areas.

Any form of resampling seems to produce chequering. I notice when viewing that chequering is dependent on zoom.

If anything, the level of detail, particularly deep red background nebula and yellow tones has improved, without too much saturation.

Try zooming. Will attempt to post 1:1 later.

[Alejandro Tombolini]

Hi,

I had a similar case (pattern) when trying to use the synthetic superbias, but it was a single attempt and did not explore why it happened. I asked about that here:
http://pixinsight.com/forum/index.php?topic=3939.msg27085#msg27085

It wasn't the same with the "natural" superbias made with 300 bias. The result was very good.

I will try again in the next calibration...

Saludos. Alejandro.

[astropixel]

It is possible to smooth out the crosshatch in lighter areas with MultiScaleMedianTransform. Dark areas tend to be more difficult. I won't bother with another post as the results are not that different, and the posted image is close to 1:1.

I wonder what the experts think about the results?