ON1 Photo RAW 2022 Sky Swap AI: is it any good?

ON1 Photo RAW 2022 Sky Swap AI tests

1. How to use the Sky tool

   There’s really nothing to it. When you open an image for editing you’ll see there’s a Sky panel. Click this, wait for the AI to do its work, then choose a sky/category from the drop-down menu below. The choice is very good, though there are a few rather lurid, somewhat grainy ones.
   
   

2. Initial results
   OK, so this hasn’t gone quite as planned. The AI masking has hit a problem with the blue sky and masked most of it but not all of it, so there are these blue patches on the right and a rather awkward transition. Worse, the light tones in the building have taken on the gloomy sky tones. The thing is, there is no control over the mask sensitivity or color range – this image’s blue sky cannot be made to mask properly.
   
   

   

3. Swapping Sky process
   OK, so let’s try another. The sky in this shot is clean and bright but a little dull. Let’s see what Sky Swap AI can do here. Whenever you select the Sky panel, ON1 Photo RAW will take a few moments to do the AI sky recognition. It’s only a few seconds, not minutes.
   

   

4. Foreground relighting
   OK, so I went a bit mad with this just to see if it’s possible to change the whole character of an image with a new sky. This hasn’t gone TOO bad, and a little experimenting with the Shift Edge, Fade Edge and Shift Horizon slides have helped keep the horizon line relatively natural-looking – though at the expense of allowing the sky to creep over the buildings on the skyline. But using the Foreground section to try to match the sky color hasn’t gone great. Even with the Amount and Distance sliders turned up to max, it still looks like what it is – two different images combined.
   

   

5. Better sky matching
   If you try a more sympathetic approach, things work out better. The original shot had a pale and misty sky, and I’ve chosen a replacement sky that’s also pale near the horizon line. The effect looks quite pleasant and quite convincing, but it did mean choosing the ‘right’ sky for the image and not trying to change its character.
   

   

6. Fine edge masking gone wrong
   But if I choose a different, more dramatic sky, the AI masking goes wrong. The Sky Swap AI simply can’t cope with the fine twigs and branches of the trees, leaving obvious edge effects against the darker sky – and the masking controls simply aren’t sophisticated enough to fix this. In this instance (and others) ON1 Photo RAW’s regular image layer, masking and blend mode tools are likely to give you a much better result.
   

   

7. Soft masking exposed
   The fact is, the Sky Swap AI tool creates a pretty soft-edged mask around complex edges. You can tighten it up with the sliders but then you create edge artefacts which are worse. It’s not alone – Photoshop’s Sky Replacement tool uses a similar ‘fudging’ technique. Indeed, if you take a close look at the mask thumbnail for the ON1 Sky Swap AI tool (it’s pretty small, so good luck), you’ll see how soft the AI mask is. This is where Luminar is simply streets ahead.
   

   

8. Sky Swap AI masking fail
   The AI masking does seem to be this tool’s weakness. The first example at the start of this walkthrough had areas of sky that should have been masked but weren’t, and this one has areas of foreground that have been wiped out by the sky and shouldn’t have been. This would not be a difficult image to mask manually – the edges are mostly straight lines – but the AI has got it completely wrong. Note also the obvious soft edge around the left side of the hotel block from the soft mask edge.