New Tool: Superbias

[ftherrmann]

Bias frames with partial columns are still not supported by the Superbias tool. Sorry for the inconvenience. We'll release a new version to overcome this limitation, but probably not before September.

...it generated a type of moire pattern.

Superbias images definitely require 24-bit STF for proper visualization. I see some screenshots posted here where normal 16-bit STFs are still being used.

Is the image I posted being displayed in 16 bit?   I selected 24 bit from the bottom of the PI screen.  I couldn't find any bit settings within the STF itself.  Could you please be a little more specific?

Thanks,

Fred

[Alejandro Tombolini]

Hi Fred,

Note the second icon in the Screen Transfer Function tool bar. That is the one you have to select.

Saludos. Alejandro.

[vpcirc]

I noticed if I tried it on a master bias that was created with BPP I got an odd pattern. I made a new master bias with image intragration with the recommended settings and then it worked perfect.

[TobiasLindemann]

Works great with my DSLR-Biases. Thank you Vicent and Juan :-)
left: masterbias with 270 frams at ISO 800
right: superbias

[naavis]

Juan,

Yes I was aware of the column issue.  I am however more concerned with the pattern that the SuperBias is producing.  This same pattern is also seen in other images posted.  I did select 24 bit from PI.  Is there a 24 bit setting somewhere else that I need to set?  I know of only one place and that's at the bottom of the PI screen.

Thanks,

Fred

I think the bottom setting only sets the bits the probe uses to show the pixel values under your cursor. The 24-bit STF setting is on the top toolbar row next to the auto STF buttons.

[MikeOates]

No one has mentioned this yet, but how do you use the vertical and horizontal option. Setting this produces two superbias frames. Do you combine them in some way?

Mike

[Juan Conejero]

No, you use just one orientation, the one that fits your bias frames. This is normally the vertical (columns) orientation. The horizontal orientation is available in case you have to work with rotated bias frames for some reason, and also for other analysis tasks, different from generation of superbias frames. For example, you can use both orientations to discover "hidden" oriented structures in your images.

[ftherrmann]

Thanks for the 24bit STF button info.  Seems like this should be included in the tool also, but I've never used it until now so not really sure it would do much other than to clutter up the control.  Maybe a tab or menu access from the STF function box?

I enabled the 24 bit and while the moire type pattern does get better it's still there.  Is the a function of not using enough bias files?

Thanks,

Fred

[Juan Conejero]

The 24-bit STF feature was released in November 2013. See this tutorial for a complete description.

There can't be moiré patterns (a special type of aliasing effect) in a superbias. However, if you look at a superbias frame at a reduced scale on the screen, especially with reduction factors of 1:3 or smaller, there can be visible aliasing patterns as a result of fast/inaccurate screen renditions of the fine bias column pattern. For a correct visualization, take a look at the superbias frame with 24-bit STF enabled at its actual size with a zoom ratio of 1:1, or at half its size with a ratio of 1:2.

[pscammp]

Hi all,
     and you think your newbies  LOL

So here i have a master Bias from 21 frames aquired with a modded
Canon 1000D DSLR and the master was produced by PI (if i even got
that right)

Not sure if i fully understand what this 24bit SFT thing is but let
me tell you tell you what i did and you can tell me if i did wrong.

1. Opened my Master Bias

2. Normal SFT applied

3. Clicked the little icon at the top of the screen which has got '24' on it (image changed a bit)

4. dropped the Superbias triangle on the image & got a black image as a result

5. Tried dropping the STF's triangle on the new image but the image stayed black and the STF's
    3 bars just reset back to default in the center of it's view (Bit Confused Here)

6. Then i just applied standard STF to the Superbias image (looked real rough)

7. Clicked on the '24' button again with the superbias version selected and the result is on the
    right in the attached pic.

Both pics in the attached image have the '24' button applied to it and the '24' was applied to the
origonal bias master before applying the Superbias to it.

So the big question is:

Is this what i want or is it horribly wrong 

Many Thanks All
Paul

[TobiasLindemann]

Hi Paul,

the picture you posted looks like a normal bias. So everything you have done is correct.
Btw.: you don´t have to use the STF at all. It is only for better visibility, you know.

To point 5: if you activate the "track-view"- button, the STF will be reset by the new picture.

Greetings
Tobias

[pscammp]

Cheers Tobias,

   I almost got something right   Wooo Hoooo

    So i assume then that this new 'Superbias' image i have here is used in place of my origonal 'Master Bias'
for the calibration/integration proccess etc

If so, what settings would i use for the .fits file when saving it, It defaults to a 32bit IEEE 754 Floating Point,
would it need to be a different one like 64bit for instance  ?

Thanks
Paul

[Mark Manner]

I can report it works very well for a 16803 chip camera [SBIG STX16803]
Thanks
Mark

[vicent_peris]

Hi,

I already have in mind what should be done to replicate the partial columns, so now we only need to find the time. But expect a new version of the tool, maybe after summer.


Best regards,
Vicent.

[Juan Conejero]

After experimenting, I found that the IMAGTYPE keyword in the Fits header needed to be changed. PI is using "Master Bias", while Maxim is looking for "BIAS". When I changed this keyword, the frames worked as expected.

I am another ACP user, so I need to use Maxim for image collection. Calibration is very convenient, since the images are calibrated as they are collected. I do not have to do anything, the calibrated images are ready the next morning. I use PI for alignment and everything after that.

Make sure that the other application is able to support the normalized [0,1] range that PixInsight uses to write floating point images, or the superbias frame won't work at all.