Can I determine background ADU?

[swag72]

I am wanting to know the background ADU on my subs. I have looked at the statistics tool and this gives me a mean and median figure ADU value which is presumably of the whole image. is there a way I can get just a background ADU figure with the image in the linear form prior to any processing?

[oldwexi]

The statistic process works also with Previews. So select with
Preview a Background area only and Statistics will get you the values, i would use the median value.

Aloha
Gerald

[chris.bailey]

Sara

OR (and there always more than one way of doing things in PI), click on the little rightward pointing arrow at the very bottom of the screen and pick a Probe sizeof 15, a 16 bit integer range and a readout mode of Median and then go back and left mouse click while moving the mouse around the background of the image. I find this gives a little more feel for any variation.

Chris

[swag72]

Two good ideas there - Thanks!!

@Chris - Can you confirm that it's the K figure that's the ADU? I'm liking that method!

[chris.bailey]

Sara

As long as you have a 16bit camera (I think you do) then a 16 bit integer K is ADU. IF you are trying to measure your sky background levels then you should carry out the measurements on calibrated images. I quite like the probe method as its quick to do a rough measure of a number of open images to get a feel for significant background changes.

Hope that helps

Chris