screen stretch

[Morten Lerager]

While working with linear astrophoto it's common to apply a screen stretch. How can this be done in Affinity photo. 

Thank you, Morten Lerager 

[RichardMH]

Can you be more specific as to what you want to do?  This sort of thing?

 

[Morten Lerager]

Thank's Richard

When a raw picture is at the linear state it is dark.

I need to ajust some narrow band color, before a dedicated tone strech.

But i can hardly see it on the screen. Often you use, what is called a screen strech.

The picture brighten up, but the file data is preserved.

My screen dump show the dark linaer picture I have to ajust before stretch.

I tried to make some change inside the "32 bit Preview", but it's not a good solution.

Most astro editing software I know can do this.

Pixinsight, Astroart, Maxim, Siril ....

 

 

[RichardMH]

this one?

 

[Morten Lerager]

No, that's a normal stretch in diff software.

Right now I use a work around.

Open the background fit file.

Ajust stretch by level and curves.

Insert a Narrowband Live procedural texture on the background.

Ajust the procedural narrowband mix.

Delete Level and curves

Insert a Normalised Tone Stretch.

Its not a real screen stretch, nor stretch enough.

But it chould do the job.