Adding additional frames to an integrated image

[kmachhi]

I have an integrated OIII image of 31 subframes.  I no longer have the sub frames.  I have recently taken another 40 OIII frames.  what is the best way to integrate these new frames with the original integrated image?

Thanks,
Khushrow

[robyx]

I have an integrated OIII image of 31 subframes.  I no longer have the sub frames.  I have recently taken another 40 OIII frames.  what is the best way to integrate these new frames with the original integrated image?

Thanks,
Khushrow

This is how I would do it: given the two masters M1 (the one with 31 subframes) and M2 (with 40 subfames) the most simple way is to weight the sum of the two taking into account the number of integrated frames I = (M1*31 + M2*40) / 71. This is something close (but not equal) to summing up the whole set of frames. The main difference I guess is on the rejection algorithm which performs differently between processing a population of 71 frames with respect subgrouping the frames into two sub sets of 31 and 40.

Despite this simple method I would personally prefer to take this formula: SNR( alpha * M1 + (1-alpha)*M2 ). By sampling  alpha between [0, 1] you can interpolate the SNR(alpha) function to find the minimum value of the SNR which is at least a sub-optimal value that you can get from this combination.

I hope this helps,
Robyx

[ngc1535]

I would just like to add- I think there is an assumption the additional data was taken with the same camera.
I dislike making assumptions... so I will add there is an additional weighting term that is folded in with the gain/sensitivities of each detector.
At least I think this is true.
-adam

[John_Gill]

Hi,

I think the issue is that the first set of images were calibrated, aligned and integrated into a single image and the individual sub-frames were deleted.  Now "Kmachhi" want to add a further 40 subs to the already created image.

My suggestion is to process the 40 subs into a single image and then something like pixelmath (sub1 + sub2) /2 or something similar.

space is not black
John

[dld]

Or just let ImageIntegration with no rejection to integrate your images with the proper SNR-based weights. Note that since you have two integrated and registered images, enter each image twice because ImageIntegration requires at least three source images.