Bringing contrast back

[Potatojunkie]

Balancing flash with ambient light can be a right pain, especially for shots you've only really got one chance to get right. If you get too much ambient coming in it sort of washes everything out and robs you of contrast, viz.:


fig1. Bit foggy, like.

It's not something you can fix by fiddling with the levels or bumping up the contrast slider, either. These affect contrast across the entire image (global contrast) while leaving you a sort of 'diffuse glow' effect over everything.


fig2. Looks 'all right', but that glow really rips my knitting.

What to do? The first step in hunting for better contrast is to take a look at your colour channels. Here the ambient was provided by a load of grubby old tungsten bulbs, many of them reflecting off of brown wooden panelling. RAW data claims the while balance point was somewhere around 2800K. No surprise, then, that the red channel seems to hold most of that fuzzy ambient glow.


fig3. Red channel! J'accuse!

The flash was only gelled to about 3200K (regular, normal person tungsten light), which means it'll have come out a little bluer than the ambient. The blue channel, then, should hold more of that crisp flash light and less of the wishy-washy ambient. And it does:


fig4. Blue channel to the rescue.

This is the luminosity information that you want to use. There are a few ways to do this, and some work better than others. As we're essentially trying to darken areas that are too light, we're going to use the 'multiply' blending mode, which does just that. Make a new Channel Mixer adjustment layer, and dial down the red while pumping up the blue. Play with it until it's pretty contrasty. You want it to be quite bright, too.


fig5. You'll pick up a bit of noise here if you're not careful. So be careful.

Now set the blending mode to multiply, and wince as everything goes really dark:


fig6. Oops.

It's okay, it's meant to do that. Just dial it back until it reaches a point you're happy with. I ended up setting the layer at 50% opacity, but the shadows were still a little dark. After merging the layers, I pulled them up a bit with the shadow/highlight tool (image>adjustments>shadow/highlight[1]). Note that this might introduce a bit of noise/posterisation into your shadows, so it's up to you if you'd rather spend a bit of time on a layer mask. Anyway, by now you should have cut through some of that haze and darkened your shadow areas.


fig6b. Somebody fucked up his numbering system.

Still not punchy enough, is it? What it wants is a boost to local contrast (fiddlier and more specific than simply adjusting global contrast). Again, there are a few ways to go about this. You could run over the whole image with the dodge/burn tools, which would take hours. You could sharpen the luminosity channel in Lab with a high radius/low amount setting[2]. My new favourite is the high pass filter. Make a duplicate layer, then hit up filters>high pass, and tweak the percentage until it comes out something like this:


fig7. Attractive, non? The setting depends on the resolution and content of your image, so experiment.

Now set the blending mode of this layer to 'soft light', and play with the opacity until you think it looks right.


fig8. Getting there.

Pow. Johnny contrast. There are still a couple of areas where that ambient glow hasn't quite been dealt with, but a few seconds with the burn tool will sort them out. While you're at it, see if you can recover any highlight detail. You'd be surprised:


fig9. This flower wasn't the featureless white blob it first appeared.

There it is. It sounds a bit fiddly, but you can do it in a couple of minutes once you're used to the process. I spent a bit of time fixing the colours (slight magenta cast) and lifting the saturation slightly, and here's the finished article:


fig10. Ye wid.

So, did that make any difference whatsoever? Well, yes. Look:


fig11. Eep.

I may be the only person who can see the difference that steps 1–6 make, but I don't care. Now let's all laugh at Robert's "I don't want to get married" face.


[1]If you don't have a keyboard shortcut set for this, set a keyboard shortcut for this. It's mad useful.

[2]See the 'clarity' slider in Lightroom? This is exactly what it does.

[Bobzilla]

The high pass filter has been my friend for this very reason for a while now

[Potatojunkie]

The high pass filter has been my friend for this very reason for a while now

See, I'd been going the high radius/low amount unsharp mask route, but the high pass filter doesn't seem to have any of the same problems with noise, even if it's a little less customisable.

[Bobzilla]

It's less customisable but when your wanting to do it to a lot of photos and you don't need that attention to detail on them all then it cuts down on the time and as you say its very good on the noise front.

I tend to use it as a basic sharpen without bringing out the noise. I've an action that I made that throws an overlayed highpass filter at my usual settings on to anything that needs a little sharpening but not to much. Stick the opacity between 20-40% and for a quick touch up its a far better result than anything I could do otherwise.

It also has the bonus of being non-destructive

[Potatojunkie]

I tend to use it as a basic sharpen without bringing out the noise. I've an action that I made that throws an overlayed highpass filter at my usual settings on to anything that needs a little sharpening but not to much. Stick the opacity between 20-40% and for a quick touch up its a far better result than anything I could do otherwise.

There's no way I could do that. Probably a terrible hindrance, but I'd much rather sit for hours and sort everything manually. Besides, even if you keep the same resolution, sharpening a close-up portrait requires completely different settings from a landscape, or an abstract texture, or a slightly-further away portrait, etc. Or you'll end up sharpening background elements that ought to be blurred. It would drive me mental.

[ianmcf]

High Pass filter is great for editing those little details like eyes and facial details that sometimes lose clarity.

if you want to get more technical, with photoshop you can create a layer specifically for the high pass filter, set the high pass filter appropriately on the whole image and then using a layer mask against that layer, gently touch in using a white/grey brush and remove using a black brush.

Makes it even more customisable and non destructive.

[Bobzilla]

High Pass filter is great for editing those little details like eyes and facial details that sometimes lose clarity.

if you want to get more technical, with photoshop you can create a layer specifically for the high pass filter, set the high pass filter appropriately on the whole image and then using a layer mask against that layer, gently touch in using a white/grey brush and remove using a black brush.

Makes it even more customisable and non destructive.

Just what I was going to say

[Potatojunkie]

I've been thinking about writing a wee tutorial on layer masks for a while, just because they're so goddamn useful. Every time I end up doing something loopy like ripping the key channel from a CMYK image for use as a layer mask, in fact.

[¡Punk!]

I don't really know much about photography but read this through sheer tedium.

I got to see a pretty girl 10 times and learned something. So today's off to a good start.

[fallen_nemesis]

I've been thinking about writing a wee tutorial on layer masks for a while, just because they're so goddamn useful. Every time I end up doing something loopy like ripping the key channel from a CMYK image for use as a layer mask, in fact.

do it!

i can't use photoshop for shit. My utter limits being using dodge and burn and arsing about with the hue/saturation channels and the crop function.

Get it done now!

[I'm Your God Now]

It's not quite as catchy as Justin Timberlakes version.

[Jesus On A Bike]

It's not quite as catchy as Justin Timberlakes version.

*Facepalm*