Note: This 3-part blog post series is now complete!
Photoshop is an incredibly powerful piece of software, and it has so many settings and tools and options that it can seem almost impossible to learn them all. One of the most useful but least understood aspects of Photoshop is the various Blending Modes that can be applied to each of your layers, or to pixels that you paint with any of the brush tools. There are a huge number of different blend modes, so we’re going to have to split this post up into at least two posts. Stay tuned for part 2 coming soon!
For those of you who tend to be purists in your photography, this might not be particularly appealing, but for those of you who love to work with your images and treat them more as sources for digital art will find blend modes enable a huge range of effects that are extremely useful. Even for the purists, though, there’s a few blending modes that are very effective at replicating processes from the physical darkroom. Best of all, you can apply them all non-destructively, of course.
During this series, we’ll take you through each of the different blend modes, and point out some ways that you’ll be able to use them in your photography. For simplicity’s sake, we’re going to look at the blending modes that are available when you’re editing an 8 bit RGB image, such as a typical JPEG file. You’ll notice that many of them operate in pairs, one affecting the image to lighten it, and the other to darken it, and both working in similar ways.
To make things as simple as possible, there are 3 different types of colours we’re going to talk about. Base pixels are the pixels on the next layer below the current one when you’re blending layers, or the pixels that are being painted over when using a brush tool. Blend pixels are the pixels that you’re painting, or the pixels that exist on the blended layer. Result pixels are what you wind up seeing after Photoshop has computed how the various blend layers will interact – your final result. Got it? Don’t worry if you have to refer back to this later, it can be a bit confusing at first.
In our example, you can see our breaking wave image with a gross orange slash across it on a separate layer – shown below is the equivalent of the ‘Normal’ blend mode. The wave image is the ‘base pixels’, and the orange is the ‘blend pixels’.
First of the blend modes is Dissolve. Well, technically ‘Normal’ is first, but we’re going to assume you can figure out how that one works 😉 Dissolve, on the other hand, randomly chooses to display either the blend pixels or the base pixels. In effect, this creates a scattered noise pattern that could be useful for faking film grain, although there are other (and usually better) ways to create the same effect.
This one is fairly self-explanatory: it compares the base pixel’s colour value with the blend pixel’s colour value and displays whichever one is darker. The only slightly confusing part is that it does this separately for each colour channel, which means that you might not get exactly the results you were expecting, due to the slightly counterintuitive way that RGB colours are blended.
Like Darken, the Multiply blend mode works based on the numerical RGB colour values of each pixel. Instead of just displaying the darker pixel, it multiplies the value of each base pixel by the corresponding blend pixel and displays the result. Since 255 is equivalent to white in each channel (the pure RGB values for pure white are 255,255,255), you’d think you’d get a lighter image – but in fact the opposite is true and the result is always darker, due to some mathematical quirk of how colour space gamuts work. No, I don’t understand it either, but hey, it works consistently.
Colour burn is a reference to a technique used in the days of physical darkrooms, with red-tinted lights and dangerous chemicals. ‘Burning’ parts of the image with additional time in the developer chemical bath increased the contrast and generally darkened the image. White pixels aren’t affected, but everything else is.
Linear burn, like colour burn, is a holdover from the darkroom days. Instead of increasing contrast between the base pixel and the blend pixel, it simply darkens the base pixel based on the value of the blend pixel. Also like colour burn, blending white pixels will have no effect.
Like Darken, Lighten is pretty self-explanatory. It compares the colour values of each base pixel with that of the corresponding blend pixel, and displays whichever colour is lighter. Also like Darken, it compares each colour channel (R, G and B) separately.
The Screen blend mode is the pair of the Multiply blending mode, except it actually works the way you might expect. Technically, the inverse of the colour value is multiplied, but either way, the result is that all your colours are lightened.
Dodging is the darkroom opposite of burning. While burning darkens the non-white pixels of an image, dodging brightens the pixels that aren’t already pure black. It’s very similar to the ‘Dodge’ tool you may already be familiar with, and works by decreasing contrast in general.
Linear dodge is similar to colour dodge, except that instead of decreasing contrast, it simply increases the brightness of the base pixels based on the colour of the blend pixels.
That’s all we have room for in today’s post, but you probably noticed that there are still quite a few left to go through. We’ll be finishing this up the list in part 2, although it may turn out that we actually need 3 parts. Once we’ve mapped out how each blend mode works, we’ll give you a few ideas about how they can best be used. Happy blending!
Note: This 3-part blog post series is now complete!