This two-parter is an accompaniment to the Photography 101 posts on the basic concepts of photography. It’s not a post that will help you take better pictures; rather, it will help you understand the pictures that you have taken, and make more meaningful edits. It’s fun and easy to mess with different filters in apps, but if you ever wanted to understand the mechanics of a photo and cut down on the ‘I wonder what will happen if I use this filter’ time you spend editing photos, this is a good place to start. Part 1 was the theory; this is the practical.
So, you remember in Part 1 how I disappointed you greatly by pointing out how you’d spent hundreds of pounds/dollars/sexual favours on procuring one of the most sophisticated bar chart computers in history. The bar chart that your camera creates – the histogram – is extremely useful in guiding how you’ll edit your photos.
What’s your favourite tool?
In this post I’m going to use Photoshop, but you don’t need something that powerful. On mobile I prefer Snapseed, which is also available as a desktop app for Windows but I haven’t tried it. Whatever editing tool you use, the features we’re about to look at will always be called Levels and Curves. Unless they’re called something else.
I won’t be discussing Instagram-style filters in this post. The only filter I ever use is a neutral density filter and although I may discuss it more fully in a future post, it’s not likely because cba. If you want to use filters in Instagram or something else, go nuts. I won’t judge you (I will) (hard).
My preference is for getting the picture you intended to get, not taking 200 pictures and then scrolling through them all like Fleabag finding a pic of her crotch that she likes and then finding the filter that works best on it. Getting it right in camera is just how I work; no shade if you want to use filters (total shade). For me, editing is just about cropping and getting the tonal spread right, but You Do YouTM.
It’s all about the midtones
You remember how the histogram works. The higher the bars on the left, the more shadows in your photo; the higher the bars on the right, the more highlights. It’s possible to get a histogram with high bars only in the middle, which would look like this:
A picture that had a histogram like this would have very few shadows or highlights. That doesn’t make it a bad picture, it just tells you that the tonal range is quite narrow. Landscapes and seascapes often look like this – there might be lots of shades of blue, green, yellow and brown (which register as midtones) but no shadows or highlights. Here’s a good example of a pic that looks like that.
This is a picture of a beach in Cornwall. You see how the colours in this picture are a little bit muted and basically flatter than the beach itself, with no real contrast and nothing to catch the eye? Us photographers have a technical term for photos like this: we call them ‘shit’.
The Photoshop histogram
Let’s have a look at how that looks in Photoshop with the histogram (if you’re using Photoshop, this is the luminosity histogram).
And in close-up:
Let’s start apply some corrections to this photo using levels. We can never fix the fact that the photographic subject is as tedious as Jacob Rees-Mogg’s leaked sex tape but we can at least make what’s there look a little more lively.
The marker on the left of the histogram (the dark arrow below the baseline) indicates the point at which tonal values in the photo become pure black. You see from the histogram that there is no pure black in our photo; but if we were to move the dark arrow to the right, we’ll change values in the photo accordingly. Similarly, the white arrow on the right moves where the highlight values start.
I’m pretty sure that will make no sense; so why don’t we look at what happens when we move these arrows about?
Doing it with Curves
Curves is a similar concept but instead of adjusting points, you adjust a straight line that represents changes to the tonal values. That’s why it’s called Curves, see, because you’re adjusting a straight line, obviously.
Imagine editing the histogram in Levels but instead of having three arrows to adjust (black, grey, white), you had 255 arrows and could adjust every tonal value individually! Wouldn’t that be a ballache. Instead, that’s why we have Curves to allow for fine-tuning. Let’s return to our picture’o’shite:
So what have we learned? More importantly, why have we learned it?
What a jolly good question. Often you won’t be able to control your lighting as much as you like. You might have too much light and not enough shadow to create a low key photo, for example. And that’s where these two tools come into their own – you can add back highlights or shadows with judicious use. You can never totally rescue a picture, unless you use RAW images, which is a whole other topic, but you can at least get closer to the effect you wanted.