No matter what editing software you use today, it will likely include layers, masking and blend modes (also known as blending modes). Everybody’s doing it now – Photoshop and Lightroom, of course, but also ON1, Luminar, Topaz, etc.
And the more software that includes blend modes, the more frustrated I get at their lack of ability to explain in plain English exactly what they are. I’ve read countless blogs, gone to workshops partly to understand them, watched countless YouTube videos looking to make sense of them, and more often than not, the recommendation of the instructor is simply to try them and see what happens. My brain needs more. I want to be able to explain them. This post will try to do that.
Before you run screaming from the room, I’m not going to give you the item by item breakdown of all of the blend modes available in any software. My intent is to help you understand what a blend mode does generally and how to make a choice among the ones you have available in your software.
If you have ever looked at a list of blend modes in any software, you no doubt were wondering where they came up with the names. The names seem almost randomly picked, and convey little to no information about the effect you can achieve by applying a blend mode to a layer on an image.
But let’s step back a bit. If you will indulge me, I will try to provide some context.
The information contained in any pixel in your digital image can be broken down into three categories: colour information, saturation information and luminance information.
Colour information (or hue) is obvious. Each pixel has a numeric colour value determined from the combination of red, blue and green channel information for that pixel.
Luminance information (or tonality) is a numeric value for how bright the pixel is. For easy reference, it’s assigned a value from 0 to 255. A value of 0 means pure black. A value of 255 means pure white. A value of 128 is a neutral grey. Everything else is some shade of grey. The plot thickens…
Saturation information is harder to describe. It is the intensity or purity of the colour. It is determined by measuring how much pure black or pure white is mixed with the colour. I’ve also seen it referred to as the measure of bandwidth in the colour, whatever that means. There doesn’t seem to be a consistent measurement scale, although sliders in most software range from -100 (no saturation) to +100 (fully saturated).
Why do you need to know this?
When you mask a layer, you are adding in or masking out the colour, luminance and saturation information for each pixel you mask. The opacity slider complicates that a bit by allowing you to select what percentage of the editing or masking effect will be applied.
Again, why do you need to know this?
Instead of simply masking in or masking out pixels, blend modes take that one step further and use mathematics to create different relationships between one, two or all three categories of pixel information mentioned above. Remember that each category of information is represented by a numeric value or values. Some blend modes add or subtract the values between the two layers; others multiply or divide them. Some blend modes mathematically combine other blend modes. Some blend modes mathematically invert other blend modes. The number of possible combinations seems infinite. And to make things even more complicated, masks and blend modes can both be used on the same layer, in combination.
At its simplest, you can pick a blend mode for colour information to determine how the colours of your blended layer will be revealed or concealed. You can pick a blend mode for luminance information to determine how darker or lighter pixels will be affected. Or you can pick a blend mode for saturation information to determine whether the more intense or the duller areas of your image will be affected.
Most editing software has “borrowed” Adobe’s collection of blend modes and even their labels to provide a seamless experience to those looking to change providers. In all these products, there has been some attempt to group or arrange blend modes in a logical sequence, since their names provide little help. Anyway, here goes:
- Normal – no mixing with the layer below; only the top layer is visible
- Dissolve – random pixels are selected from each layer; depending on the associated opacity, top or bottom layer may be dominant
- Darken, Multiply, Color Burn, Linear Burn, Darker Color – each of these makes the blended result darker; despite these options, Multiply is most often used; it does as it says – multiplies the numeric values in the top and bottom layer together
- Lighten, Screen, Color Dodge, Linear Dodge, Lighter Color – each of these makes the blended result lighter; despite these options, Screen is most often used; it inverts, then multiplies the numeric values, then inverts them again
- Overlay, Soft Light, Hard Light, Vivid Light, Linear Light, Pin Light, Hard Mix – each of these combines two of the previous blend modes; despite these options, Overlay is most often used; it combines Screen and Multiply
- Difference, Exclusion, Subtract, Divide – each of these applies straight arithmetic to isolate differences between the two layers; they are useful for addressing specific problems like colour casts or the need to align two images before masking
- Hue, Saturation, Color, Luminosity – as the names imply, these blend modes will act selectively on one category of information; each will preserve the other categories from the bottom layer while applying the designated category of information from the top layer
With all these choices, the advice of just trying it and seeing what happens might actually make sense. As noted, most average photo editors (you and me) employ just 3-4 of these blend modes. The others seem to be there because, well, someone figured out a formula.
Luckily, trying out a blend mode is now easy. In all software that I have used, I can now hover over the blend mode name and see a preview of the effect before I apply it. It’s easy to scroll up and down the list. That wasn’t always the case. Not so long ago, each had to be applied, then deleted, then the next applied in order to find the right effect. It was time consuming.
If you think about it, everything we do in photo editing is about changing the numeric values of the pixels in our images. Whether it’s moving a contrast slider or lowering the opacity or applying a blend mode, the resulting image will have pixel values different from the original image. So make it a point to explore blend modes as a regular part of your workflow. The effect might be just the ticket to a stunning image.
Footnote: in case you haven’t had enough, here is a great introduction to blend modes:
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