Luminar 4 Sky Replacement AI

I’ve made a few comments about the performance of Luminar 4. Specifically, how it’s slow to come online and once online, its difficulty with showing me the thumbnails of the photos I have. Then, when I’m editing a photo, it’s slow in updating the preview of the available canned “looks”.

I want to take my hat off to Skylum Support (the people who released Luminar 4 and also offer Aurora HDR 2019). They are responsive and knowledgeable and were able to point to things I could do to speed up things. For instance, among other things, they showed me where Windows 10 had hidden the option to assign High Performance computing to individual apps. Turning on the NVIDIA GPU for processing really speeded things up.

Still not great, but here’s the thing . . . I asked Luminar to load all 108,000 photos on my hard drive into one catalog. Nearly all are large RAW files. I mean, I don’t do that with any other program. Lightroom, for instance, is arranged by libraries for each year; at most, each Lightroom library has between 8,000 and 10,000 photos.

Considering what I’m asking it to do, Luminar 4 is pretty good. Skylum are supposed to release a new version to speed things up, but, again, just the tweaks I made let me work at a comfortable speed.

And, what did I do? Well, I tried out their Sky Replacement AI tool. So, for instance, I picked this photo:

Opened up the Sky Replacement AI tool, picked a sky and, in less than three seconds, this . . .

Pick another sky and . . .

OK, so the shadow isn’t matching the scene, but the important thing here is this: I didn’t have to mask anything or pick anything. The program did it all on its own.

Say you want a sunset . . .

. . . but you want it on the other side . . .

Or, you want fewer clouds in your sunset . . .

It even has an option to recolor the photo to more closely match the sky.

Want a night shot? Say no more.

Here’s a gallery of a few more replacements I tried.

For the last shot, I added sun rays (you can pick a number of variables and also position the sun)

Again, the shadow under the plane is a problem that limits the type of sky that works with the scene. Luckily, I have a crapload of sky photos to choose from in addition to the ones they provide.

But, you say, that’s a fairly easy sky to replace.

Fair point. How about this:

It works in B&W as well . . .

Anyone who’s played around with masking landscape scenes — and who is not an expert at it — ought to be suitably impressed.If I were doing that, I’d have to mask all the wires and tree branches and poles and the bird. Not a trivial matter, although there are tricks one can use to help.

Luminar 4 had difficulty replacing the sky when clouds blended in with a mountain. There is an option to manually alter the mask, but I didn’t bother with it. I assume snowcapped mountains without a clear definition of the transition to the sky would also give the AI trouble.


Edited to add: However, if one is judicious in choosing a replacement sky, it still looks seamless.

If the clouds are reasonably well-defined, it seems to make makes pretty good decisions as to about what to replace.


Even in this next photo — which I would find difficult to mask — it did pretty well.


But, how is it with antelopes and trees, you ask?


I’d say it did a good job.

Remember, these are single clicks and something like 2-5 seconds to replace the sky.

I tried doing a night scene of the above photo . . .

I need to learn the tool more, because manually editing the composite after replacing the sky seems to fight with the blending of the sky because I couldn’t quite make it “look” like night after I changed the sky.

However, I took this photo and did a “nighttime” conversion by adding lots of blue and reducing the exposure before replacing the sky . . .

Not perfect, but pretty good. And yes, you can click on the photos for a larger version.

I should also mention I didn’t post-process the blended images. I think all of them can be made to look even better. Still, for a few second’s work on each, they are more than acceptable.

One other thing . . . I mentioned you have the option of loading your own sky. BUT . . . it need not be a photo of a sky.

OK, those are pretty silly . . .

. . . but this is kind of neat.

See, if I wanted to blend those photos, it would take me a bit longer than a few clicks and waiting three seconds.

There’s a lot I’ve yet to explore in Luminar 4. Lots of settings I still haven’t played with. But, I can definitely see a use for the sky replacement tool.

Which brings me to this question . . . can we truly trust anything we see in photos?

. . . or, soon enough, video?

Here’s the gallery of all the photos:

That’s it. This post has ended . . . except for the stuff below.


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