Help Processing/Stacking

[Herzy]

I took 4 shots of M51 (I know that's not a lot) and I attempted to stack them to reduce noise. First I tried stacking in Nebulosity. Despite watching multiple tutorials, I failed over and over again. I then moved to Lynkeos, and stacked all 4. The noise of the image went down, but the actual Galaxy didn't become any brighter...? I thought stacking merges the pictures and makes the subject brighter? 

Anyways, I then attempted processing. I spent like 3 hours of watching tutorials and trying to make it look better, but I really couldn't make that much of a change from the original. How should I process my images? 

PS: I know this is a lot to ask, but if anyone has some spare time can you download my image and process it yourself so I can see how much good processing can improve an image? Thanks!

[wxsatuser]

Any form of averaging will not brighten the image.

You have to stretch the linear data to reveal the image, at the same time any noise will become
apparent depending on how much data you have collected.

If you provide the stacked unstretched image I'm sure someone will have a go at it.

[Herzy]

So stacking simply reduces noise which allows for processing without amplifying the noise? So if I take 3000 photos I will have practically no noise after stacking?

[wxsatuser]

23 hours ago, Herzy said:

So stacking simply reduces noise which allows for processing without amplifying the noise? So if I take 3000 photos I will have practically no noise after stacking?

The SNR increases with the square root of the total exposures.
If you took 16 lights the SNR increases by 4, 25 lights by 5 etc.

There is a law of diminishing returns, 3000 in this case may be over the top.
What you have to watch with very  short exposures is they won't match a stack of longer exposures
because they will capture so little photons. Plus they want to be long enough to overcome read noise.