ADU values

@snoraste Hi Shayan, there is no way to see the stats of all lights at the same time. But you can double click any light in the file list and then hover your mouse over the image. APP will then show the ADU values of the pixel under the mouse in the upper bar of the application window:

HTH, Wouter

Thank you. Just to confirm, there's no way to see min,max, background ADU, correct? Also we cannot select a region within LIGHTS to get the mean ADU?

Not with a specific region no, for what use-case would you want that? Just for me to understand better, might be something Mabula can add to his to-do list.

thank you.

The idea is to measure background ADU for an "optimum" exposure of swamping the read noise. For that, I would need to identify a region of the image that is "background" (no stars or nebulosity) and measure an average ADU. I know I can move my cursor along different regions and a point estimate of ADU, but looking for an average number really. Unless there's a better method of measuring mean background ADU in APP?

Posted by: @wvreeven

APP will then show the ADU values of the pixel under the mouse in the upper bar of the application window

Hi @wvreeven

Where should ADU be? In the upper bar I always see X,Y,R,G,B values, not ADU numbers. See screenshot attached. 

Thanks

The background column in the table tells you about the mean ADU, for 16-bit data and 32-bit data this value will differ accordingly.

Posted by: @vincent-mod

The background column in the table tells you about the mean ADU, for 16-bit data and 32-bit data this value will differ accordingly.

Where is it, please? Can you make a screenshot?

Thanks

So the value is normalized (so not between 0-65536, but between 0-1) and you can see it here;

Posted by: @vincent-mod

So the value is normalized (so not between 0-65536, but between 0-1) and you can see it here;

Background is different from ADU...We are speaking about finding ADU values somewhere in APP...

So I think there are no ADU numbers in APP. I didn't see it since I've been using APP for 2 years....

Thanks

Hi all @snoraste , @wvreeven, @vincent-mod, @ippiu

Let me clarify and explain everything 😉

APP does show ADU values for all Masters, so the Calibration Masters and the Light Frame Integration, in the metadata/FITS header of the files:

BG-1 = ' 1,3835E-02' / background estimate of channel 1
SCALE-1 = ' 4,7350E-04' / dispersion of channel 1
NOISE-1 = ' 3,2280E-04' / noise level of channel 1
SNR-1 = ' 1,5204E+00' / Signal to Noise Ratio of channel 1

These are ADU values of Background, dispersion/scale (which is a robust measure and better than the average and better than the median), noise and Signal to Noise Ratio.

For the individual lights, the ADU values for Background, dispersion/scale, noise and Signal to Noise Ratio are reported in the bottom frame list panel like Vincent indicated after the normalization stage 5).

These values are reported in 32bits normalized floats, which means that the original 16bits integer values between 0-65535 are mapped to 0-1.

As Wouter indicates, the ADU values that you see above the image viewer when you move the mouse over the image data are the values as shown in the image viewer. So if the preview filter is stretching your data, then you will see the stretched ADU values. If you want to see the linear ADU values of a region in your image, simply set the DDP preset to No Stretch, data as is and move your mouse over the region of interest 😉

APP currently does not have an option to see for a single file the ADU values for average, median, robust scale, noise, SNR etc directly, but this will soon be possible using a new image viewer mode.

Mabula