Replacing the sky in an image

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    Topic: Replacing the sky in an image Read 1151 Times
  • Peter Gallagher
    Peter Gallagher
    Participant
    Posts: 12
    Other Raw Converters
    on: January 20, 2020 at 5:01 am

    I recently purchased Sklyum’s Luminar 4.1 whose signature advance is an automatic sky replacement facility that they claim is controlled by ‘artificial intelligence’ — by which I assume they mean methods informed by machine learning. It finds sky backgrounds and replaces them with an alternate sky image using blending techniques that intentionally ‘leak’ into the foreground to ‘relight’ the scene. It often works flawlessly when you use the Skylum sky-replacement images — especially where there’s a clear horizon — but, as I found, much less often when I used my own sky images.

    I’m certainly not averse to improving dull images ‘artificially’. Photography is artifice in my view. Still, the artifice must carry conviction: that was where I found a  problem.

    The Skylum marketing showed the replacement blend worked surprising well. I found that was ‘sort of’ borne out in use. The big problem for me was to stop the replacement sky leaking too much into the rest of the scene. I found the new sky would often muddy or stain the foreground near the horizon. I tried using the available Luminar masking tools to reduce this leakage, but failed. Luminar has limited local selection tools (brush, gradient) that respond slowly and unpredictably on my (fully spec’d 2019 iMac) and no edge-aware selections. I found it horribly difficult to mask our or erase the ‘sky-replacement filter’ in the foreground. When I (sort of) succeeded, the time it took made the effort just too expensive to justify the results.

    I tried several Photoshop sky replacement techniques recently while I was considering the Luminar  purchase. None was more successful than Luminar and each was time-consuming. None of them (using ‘blend-if’, or channels or gaussian blurs to clear up ‘leaks’ into the middle- or foreground) was uniformly useful. I believe it is possible to make convincing sky replacements in PS. But, for my images anyway, I found it takes too much effort and time-consuming attention to minuscule details. Worse, the end result of ecstasies of fiddling often failed to convince (me at least) for reasons that were subtle but unmissable.

    Finally, I’ve reached the conclusion that if an image needs sky-replacement to make it more interesting then it’s very likely due to poor technique on my part. Either I made the wrong image OR I made the image wrongly. In the majority of cases I could have made a much more successful image simply by bracketing my exposure. In some cases, the RAW file contains sufficient information for me to ‘rescue’ the image or improve it if I process carefully in Lightroom. In other cases, I simply framed the image badly or was not close enough to my subject.

    By the way: I apologize for being the only member to break the silence in this part of the Forum. I really have no agenda in doing so.

    Jeremy Roussak
    Jeremy Roussak
    Keymaster
    Posts: 230
    Re: Replacing the sky in an image
    Reply #1 on: January 20, 2020 at 5:51 am

    No apology is necessary, Peter!

    I’m interested in your experience. I’d been tempted to buy an upgrade to my (barely used) old version of Luminar, but the discount they were offering wasn’t huge, so I didn’t rush. I viewed the claims they made of the sky substitution abilities with scepticism and you seem to show that it was at least partly justified.

    Maybe the solution is always to take images that conform to their examples.

    Jeremy

    Kevin Raber
    Kevin Raber
    Keymaster
    Posts: 554
    Re: Replacing the sky in an image
    Reply #2 on: January 21, 2020 at 11:01 am

    Peter, I am still messing around with Skylum 4.1 and I am surprised at how often it works as advertised.  I bought a ton of sky files years ago and many of my own that I shoot for that purpose and these are working well too.  I do find I need to go and clean up some spillage but that is usually in areas that are like the sky likely confusing the program.  Also, it doesn’t do reflections of the new sky in water well.  There is a way to do it.  I’m told they are working on a reflection feature in the future.

    Skylum has done some amazing things in their apps.  They have come a long way in a few years.

     

    Kevin Raber
    CEO & Publisher of PhotoPXL.com and Rockhopperworkshops.com

    Mike Nelson Pedde
    Mike Nelson Pedde
    Participant
    Posts: 465
    Re: Replacing the sky in an image
    Reply #3 on: January 23, 2020 at 10:10 pm
    No need for apologies, Peter: glad to have your voice. I posted something on this in another thread, but the system won’t allow me to copy/paste it here. The other thread is: https://photopxl.com/forums/topic/creating-photographic-art/ (reply #4)
    Mike.

    _____
    Mike Nelson Pedde
    Victoria, BC
    https://www.wolfnowl.com/

    Greg Scott
    Greg Scott
    Participant
    Posts: 10
    Re: Replacing the sky in an image
    Reply #4 on: February 1, 2020 at 6:15 pm

    I also use Skylum for sky replacements and luminosity masks in Photoshop.  Like Kevin, I have a selection of different sky types.  One problem with these is the sizes are small when compared to the image I am attempting to modify.  My current strategy for upsizing is to use one of two tools produced by Topaz to prevent banding problems.  One is JPG to RAW and the other is Gigapixel.  Both of these tools upsize images using AI to make decisions about how new pixels are created.  I am able to examine images on a 65″ flat panel and the quality does hold up well.

    Good discussion.  It is helpful to hear what others are doing in this area.

    Mike Nelson Pedde
    Mike Nelson Pedde
    Participant
    Posts: 465
    Re: Replacing the sky in an image
    Reply #5 on: February 29, 2020 at 2:55 pm

    By the way: I apologize for being the only member to break the silence in this part of the Forum. I really have no agenda in doing so.

    Peter: Glad to hear your voice! No need for apologies.

    I posted this in another forum recently, but it fits here:

    Came across this on Tumblr yesterday. It’s the photographer’s work and he’s welcome to do with it what he wants, but if I’d seen these in a gallery I’d think, “Great clouds, but interchangeable foregrounds?” To each his or her own, as the case may be.

    https://expressions-of-nature.com/post/190331975116/te5seract-%C3%BCbers-feld-in-richtung-sturm

    Mike.

    _____
    Mike Nelson Pedde
    Victoria, BC
    https://www.wolfnowl.com/

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