Using "Multiscale high pass" on deep sky images

[Rudi]

I have been thinking about, how I could get more dynamics in deep sky images with Astroart.

Then I thought about the "wavelets" function, as we know from Registax. Wavelets is using fourier transformations to enhance the dynamics in an image.
This should also be possible to use on deep sky images?

And yes, Astroart 7 do indeed have such function, "Multiscale high pass", MHP, in the Filter menu.
As with Wavelets in Registac, the function should be used gently, or else it will do more damage than good.
You will need to experiment with your own images.

Here's a few examples of what "MHP" can do in Astroart 7

M106 before and after MHP


NGC4217 before and after MHP


An example, step by step

Here, I will briefly show, what I did on my latest image: M106 og NGC4217

You need to carefully apply the MHP on the galaxies areas one by one. You can not apply MHP on the entiere image, that will ruin the stars.

First you need to create a mask, that covers the ares 100%, that you want enhanced, here I am masking the disc in NGC4217:


Once the area is marked, the area needs to be softened, then the MHP impact will gradually decrase towards the borders, use "Smooth" for this:


And now the fun part begins, open MHP from the Tools menu:


If you press the "Preview" padlock icon, then you can watch the effect of the adjustments live.
And by pressing and holding "Compare" button, you can blink the before and after effect.
Be careful, do not over do it


This is entierely new to me. I dont know, why I haven't thought about this before?
I hope that other AA7 users can use this!

[agd.alberto]

Rudi, thanks, I experimented. Very well

[it344x]

bumping this thread as it is very, very useful.
If there is a way to create a mask and use the histogram stretch ONLY on the mask section that would enhance this ability even more.
For example, I want to select a galaxy, invert the mask selection and change the rest of the image leaving the galaxy alone, but histogram stretch changes the entire image.

[dredger]

Thanks for the tutorial on this, very helpful.

[WD5IKX]

Great info....I just shot a bunch of galaxy images under poor seeing conditions and this gives me a better understanding of how to use it.

Thanks......now back to processing....

[jauunton]

bumping this thread as it is very, very useful.
If there is a way to create a mask and use the histogram stretch ONLY on the mask section that would enhance this ability even more.
For example, I want to select a galaxy, invert the mask selection and change the rest of the image leaving the galaxy alone, but histogram stretch changes the entire image.

Hi - this can be done -

Mask the area you want to stretch, copy the selected area to a new image, stretch as required, then register the images and merge back to the original using max or blending as you wish. Here is an eg using one of the sample images.