Unpicking Snapseed's Ambiance slider

If you use Snapseed to edit your smartphone photos, you might have noticed the 'Ambiance' slider under the 'Tune Image' settings. Ambiance? Isn't that the mood or feeling you get at a party, not a photographic term? Yes, exactly, and that's why I avoided it for quite a while. I just couldn't figure out how to apply it effectively to my photos. And Google, which owns Snapseed, was hardly helpful. The Google help page ambiance explanation reads:

The Ambiance control is a special type of contrast that controls the balance of light in a photo. It can be used to balance backlit photos or to accentuate contrasts throughout your photo. Swipe right for photos where the subject is darker than the background. Swipe left to increase the contrast of dark objects and create a slight glow around darker objects. This is especially helpful in photos that are slightly flat.

I wasn't aware that there was a 'special type of contrast' available to photographers, just the plain old difference between light and dark, so that was surprising. And it's all very well telling us to 'swipe right for photos where the subject is darker than the background,' but what effect will it have?

As with just about everything associated with photography, the best way to understand it is to use it. So that's how I've come to write this and present you with some compare-and-contrast examples where I have swept the slider both left and right on a series of photos and analysed its impact.

In order to create examples that are clear enough for illustrative purposes, all of the ambiance settings, whether positive or negative, have been exaggerated. Subtlety and demonstration aren't natural bedfellows; that's for the real thing.

Dried berries

Let's start with this image of some dried berries. I've adjusted the white balance to correct for a light temperature that was out by several thousand Kelvin and cropped it marginally, but that's all. It's a good base.

By increasing the ambiance setting by 60 points, you can see that the image has taken on a more reddish tone. The background has also been lightened, but the highlights—say those on the bottom right of the centre berry—haven't become overwhelming, as you might otherwise expect from an increase in contrast. The definition of the berries has improved, but not at expense of the highlights.

When I swiped the slider to the left and dropped the ambiance by 60 points, you can see that the background became darker, the red tone has diminished, and the berries have become softer looking and less defined. A negative ambiance setting has given the photo a softer, more muted look.

Eva

This is my niece, Eva. She's three. She's being spun (by me) on an upright-spinny-device in the park. I've adjusted the original image to correct the white balance, but that's it.

When I increased the ambiance, pushing it to +60 made Eva look as if she's been on a sunbed every day of her life since birth. It was awful. So I went for +30 instead. She still looks comically rosy-cheeked, but not horrifically so. Her coat is an unattractively bright shade of pink, her wellies are deeply saturated, but the grass looks good.

Decreasing the ambiance to -30 had a rather pleasing effect, though. Her skin became more milky and the darker background helped her to gain even prominance in the image. I reckon that decreasing it even further could make for an even better look.

Me

Having tried increasing ambiance in Eva's portrait to unpleasant effect, I didn't even bother trying it with my self-portrait. Decreasing the ambiance, this time to -100, was effective, though. I'm not sure if I prefer the original (again, slightly cropped and heavily adjusted for white balance) image or the edited one, but it's a good demonstration of the tool and shows how it gives a more muted feel to your photos.

Having a swipe and swish with the ambiance slider is definitely something to be considered when you're fiddling with your smartphone photos. The general rule seems to be that left is great for portraits and go right a bit for still lifes. But every photo's different. And maybe 'ambiance' isn't such a terrible descriptor, either. One way is more lively and bouncy and the other more muted and moody. Just like the atmosphere can be at a party.

The wild blue yonder of straight horizons

Horizons: they are very definitely meant to be level in our photos. Whenever I see a lop-sided horizon, it sets my teeth on edge. Nature intended that they be straight, at least as far as our eyes can see, and our inner ear knows this. A wonky horizon will likely make anyone looking at it feel uncomfortable, as their eyes will be telling them one thing and their feet another, but they won't necessarily be able to pin-point why. And you definitely don't want that.

They also seem to be something that I am perenially unable to get right when I take a photo. (Unless I'm using a tripod, of course, then you use a dinky spirit cube in your hot shoe.) I know that they need to be level, so I try my utmost to make them that way, but they always need tweaking. I don't know, maybe I stand funny, or something.

The fix, however, is easy. Whether you're using a free online editing service or have the mighty power of Lightroom or Aperture behind you, there're tools to straighten photos. I've picked two as examples - one free, the other paid-for and swanky - to give you an idea.

If you use Pixlr (Pixlr.com, possibly my new free online suite of choice, following the demise of Picnik), it's very simple. Upload your JPEG photo into Pixlr Express, select Adjustment, and then Rotate. Then all you need to do is use the slider to alter the angle of the image so that the horizon comes up straight. There's even a useful grid to help you get it right.

Use Lightroom 3 and you have three straighten options, all of which are found in the Crop panel on the right-hand side. The first is under the Crop tool, and you adjust the angle by eye, using a grid overlaid on the image to help you. The second uses the slider, allowing you to adjust the slant of the image by a precise number of degrees. The third is by far the easiest. Click on the Angle tool and then use it to draw on your image, following the line of the horizon. It'll correct the angle of the image to that line. Simple! (And it also works the same for vertical alignment, too, ensuring that buildings don't lean to the left, or whatever.)

Of course, if you want to deliberately set your skyline askew, there's nothing wrong with that and you can use these same tools to achieve that end. Just make sure that it's off-kilter enough that it's easily identifiable as deliberate. (And I'm reliably informed by one Haje Jan Kamps that a purposefully skewed horizon is called a 'Dutch Tilt'.)

If you're now permanently unable to look at another picture without being able to spot the wonky skyline, I'm sorry. But you never have an excuse to be riding off into a crooked sunset again!