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INDI Library v1.8.1 Released (09 Sep 2019)

Monthly maintenance release INDI v1.8.1

ASI Camera bit size persistence issue

3 weeks 3 days ago
DaveH
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ASI Camera bit size persistence issue #45704
Hi,

I am using ASI cameras that support a 12-bit ADC. When I use the default Ekos/INDI settings I notice that the INDI Control Panel shows that the 8-bit Raw Format is selected. This then results in my captured images being saved as only 8-bit FITS files i.e. stats show a maximum value of 255. Reading the docs, I picked up that 8 and 16 bit FITS are supported and to recover the extra 4 bits I will need to use the 16-bit format. When I then view the FITS stats, am I correct in saying that the 12-bit values are scaled up to fit a 16 bit values i.e. 0-4096 -> 0-65535? Also, when I exit and re-run the software the Format always defaults back to 8-bits. Is there a way to force the setting to stay at 16-bit?

Many thanks.

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3 weeks 2 days ago 3 weeks 2 days ago by Ihoujin.
Ihoujin
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ASI Camera bit size persistence issue #45717
Going up to 16 bits will store 12 bits faithfully, is not scaled in any way to fill 16 bits. The extra bits are just zeros.

Save the ASI INDI driver configuration to have it remember the 16bit setting.

INDI/KStars on Raspberry Pi 4, 4gb
Raspbian Buster with AstroPi3 script configuration
Skywatcher HEQ5 Pro Mount
Canon 600D Camera
Orion SSAG/ASI120mm @280mm Guide Scope
PHD2
Adafruit Motor Hat shield
Adafruit GPS Module
Generic Bluetooth Joystick.
Startech 7 port powered USB Hub.
The following user(s) said Thank You knro, Herrhausen

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3 weeks 2 days ago
wvreeven
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ASI Camera bit size persistence issue #45726
This was recently discussed here:

www.indilib.org/forum/wish-list/5997-dri...ebth-as-default.html

As you can see Jasem has made sure that in future versions of INDI the default bit depth is set to 16 bits. Please read the rest of the comments in the thread as well.


HTH, Wouter

ASI1600MM-Pro Cooled and filter wheel with a SkyWatcher Esprit 80 ED on a SkyWatcher HEQ5-Pro

ASI1600MM-Pro Cooled and filter wheel with an 8" TS Ritchey-Chrétien on a SkyWatcher EQ6-R

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3 weeks 5 hours ago
DerPit
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ASI Camera bit size persistence issue #45816

Ihoujin wrote: Going up to 16 bits will store 12 bits faithfully, is not scaled in any way to fill 16 bits. The extra bits are just zeros.


Uh, no. At least the ASI cameras save their 16bit data left-aligned, i.e., the counts will be 0->65535, but increasing in 4bit = 16 count steps.

openSUSE Tumbleweed KStars git INDI git
GPDX+EQMOD, CEM60EC, ASI1600+EFW+ASI290 mini

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3 weeks 4 hours ago
ChrisRowland
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ASI Camera bit size persistence issue #45817
Curious why it's better to have the data left shifted, I can't think of any good reason.

Chris

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2 weeks 5 days ago
Ihoujin
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ASI Camera bit size persistence issue #45844

DerPit wrote:

Ihoujin wrote: Going up to 16 bits will store 12 bits faithfully, is not scaled in any way to fill 16 bits. The extra bits are just zeros.


Uh, no. At least the ASI cameras save their 16bit data left-aligned, i.e., the counts will be 0->65535, but increasing in 4bit = 16 count steps.


I don't believe my statement was incorrect. For reference I found this explanation.
engineering.stackexchange.com/questions/...ustified-adc-results
If I understand correctly, Left-justified would be read as 0x123456789ABC0000 (would be binary in reality). Example being representative of 12 bits of information in a 16 bit register. The extra bits being zeros, as I said.

INDI/KStars on Raspberry Pi 4, 4gb
Raspbian Buster with AstroPi3 script configuration
Skywatcher HEQ5 Pro Mount
Canon 600D Camera
Orion SSAG/ASI120mm @280mm Guide Scope
PHD2
Adafruit Motor Hat shield
Adafruit GPS Module
Generic Bluetooth Joystick.
Startech 7 port powered USB Hub.

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2 weeks 5 days ago
DerPit
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ASI Camera bit size persistence issue #45860
Might be a semantic disagreement ;)
Yes, the result from the ADC will be padded with zeros. Padded on the right side. So the max value from the ADC (4095 = '111111111111') will be placed in 16bit as '1111111111110000'. Expressed in 16-bit, this is a four-fold bit shift left of the value 4095, which corresponds to a multiplication with 16. I'd well call that 'scaling'.
Upshot is, the data you get from ASIs is 0->65520, not 0->4095.

openSUSE Tumbleweed KStars git INDI git
GPDX+EQMOD, CEM60EC, ASI1600+EFW+ASI290 mini

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2 weeks 5 days ago
Herrhausen
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ASI Camera bit size persistence issue #45864
The data is shifted only, it's not being scaled.

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2 weeks 5 days ago
DerPit
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ASI Camera bit size persistence issue #45870
Somewhat getting ridiculous.....
At least tell me then how 'scaling' would look in your opinion (and why multiplication is not scaling.....)

openSUSE Tumbleweed KStars git INDI git
GPDX+EQMOD, CEM60EC, ASI1600+EFW+ASI290 mini

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2 weeks 5 days ago
Ihoujin
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ASI Camera bit size persistence issue #45882
Point is the data is faithfully stored within. There is no loss or additional information, just some padding.

INDI/KStars on Raspberry Pi 4, 4gb
Raspbian Buster with AstroPi3 script configuration
Skywatcher HEQ5 Pro Mount
Canon 600D Camera
Orion SSAG/ASI120mm @280mm Guide Scope
PHD2
Adafruit Motor Hat shield
Adafruit GPS Module
Generic Bluetooth Joystick.
Startech 7 port powered USB Hub.

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