Blend Modes are a way of controlling how different Layers in a stack of images interact with each other. Essentially you use them by targeting a specific tonal characteristic you want to use. Before jumping into how to use them though, it is worth understanding what all the modes are.
The illustration below indicates all of the types of blend modes that are available to you.
There are 27 different blend modes available to you, and to explain how each are applied would definitely require an excursion into mathematics, would almost certainly be inapplicable for 99.9% of photographers, and would probably have you jumping straight into the next chapter. So instead, we will cover the 5 Blend Modes that are used most frequently in photography, complete with their practical application.
NORMAL BLEND MODE
When you first create a layer, the blend mode defaults to Normal. In this mode, an image at the top of the layers will hide a layer below it. You can change the opacity of the top layer so that it is slightly opaque, but this is all from the perspective of blending the two layers together creatively. So, the Normal Blend Mode is used in photography when you don’t want to apply any special effects between the Layers.
MULTIPLY BLEND MODE
Multiply faithfully multiplies the pixels in the upper and lower Layer with each other. It does this by assigning white a value of zero, and black a value of 1. This means that black pixels remain unchanged, and white pixels get removed, but all other pixels become tonally mixed. The effect is that where layers intersect with each other, you get the same effect as you would get mixing paint. You can see that in the image illustrated above, where the intersections of blue and orange have made green. Exactly like mixing paint! The Multiply Blend Mode is great for adding vignettes to images, as well as adding dark objects to light backgrounds.
SCREEN BLEND MODE
Screen is a multiplying blend mode that replaces pixels similar to the Multiply mode described above; except it factors the blend on the lightest tones of the two layers. What does this mean practically? Well, Screen Blend Mode is great if you want to add objects to an image that are screened on a black background, because it hides all the black tones and leaves you with just the object. So again, it’s great for Blend Mode masking techniques such as adding smoke or steam to an image.
OVERLAY BLEND MODE
Overlay is fantastic for blending photos together whilst maintaining detail, and contrast between the two layers. It blends the hues in an additive or subtractive way based on the base layer color.
SOFT LIGHT BLEND MODE
Soft Light works in a similar way to Overlay but you end up with a less contrasty result. Therefore, it makes a good fall-back option when blending two layers in cases where there is too much contrast using Overlay Mode. Soft Light is also quite useful for giving the impression of sharpness in an image by increasing edge contrast.
Worked Examples
Example 1: APPLYING A VIGNETTE TO AN IMAGE (MULTIPLY BLEND MODE)
Unlike lens vignettes, which can look harsh and ugly, a gradient vignette added during post-processing can add subtle emphasis to your subject. Vignetting is a reduction in an image saturation and/or brightness towards the edges of the image, as compared to the centre of the image.
STEP 1: With the image opened in Photoshop, and working from the Layers Tab duplicate the Background Layer by dragging the Layer to the ‘Add New Layer’ icon. With the Layer selected, you can also use ‘Shift Command N’ (on a Mac) or ‘Shift Control N’ (on a PC). You don’t need to do this, but it helps you do a before/after view as you can hide the Layers.
STEP 2: Select the uppermost layer in the stack, and then create a new blank layer using ‘Shift Command N’ (on a Mac) or ‘Shift Control N’ (on a PC).
We are going to place our Vignette onto this blank Layer. To do this, we use the Gradient Tool.
STEP 3: Making sure you have the new blank Layer selected, as well as the Gradient Tool, click a point around the subjects face, and drag a line to the edge of the photo, as illustrated below. This will add a focal point drawing the eye into the image, as the eye is naturally drawn from dark areas into brighter areas.
When you release the mouse, your gradient will be displayed on the Layer as solid color from white to black (illustrated below). Incidentally, if your gradient is going black from the centre, you can press Command I (on a Mac) or Control I (on a PC) to invert your selection.
STEP 4: Set the Opacity of the new gradient layer to around 50% from the Layers Tab. This helps to ensure the gradient is being applied from the correct area of the image. At this point, if you aren’t happy with your vignette location, you can re-apply the gradient until you get it just right.
You can see from this though that the white elements of the gradient are making the image look foggy. However, Here comes the magic! Remember we said that with the Multiply Blend Mode, that, white pixels are assigned a mathematical value of 0 when they are mixed with the layer below it? Well, this means that we can eliminate the white pixels from this gradient using the Multiply Blend Mode!
STEP 5: With the new gradient layer selected, choose the Multiply Blend Mode. Now we can see that the white pixels have magically disappeared, leaving us with a dark vignette.
At this point, you can adjust the Opacity of the layer to change the intensity of the vignette to your liking. But, you can see from this example how easy it is to apply vignettes in Photoshop using Blend Modes.
EXAMPLE 2: AUGMENTED SKIES OR ANYTHING! (MULTIPLY BLEND MODE)
This guided workflow is called augmented skies, but to be honest, you can pretty much use this technique to augment any image.
What we are going to demonstrate, is how to combine this image of a buzzard into this landscape. Now, you might be thinking; ‘you can easily do this with a selection to grab the object, and then paste it directly onto the landscape’? The answer to this being yes you can. When you make selections, however clever the algorithms are that power them, and however good your masking skills are, invariably you are going to lose some fine details. Whether that be hair, or fur or feathers or something else, elements will be lost in the image isolation process.
STEP 1: Open both of the images up in Photoshop. Working firstly from the image of the bird, select ‘Command A’ on a Mac or ‘Control A’ on a PC, and this selects the whole image. You can also go to the Application Bar and head to ‘Select > All’ if you wish.
With the selection made, use another short-code ‘Command C’ (on a Mac) or ‘Control C’ on a PC to copy the selection into the clipboard. Again, you can go the long-way around for this step using the Application Bar and head to ‘Edit > Copy’ if you wish.
STEP 2: Moving now into the landscape image and using the short-code ‘Command V’ (on a Mac) or ‘Control V’ (on a PC) to Paste the image of the buzzard onto the landscape layer. You can of course head to the Application Bar and use ‘Edit > Paste’ for this step if you wish. You should now have something that looks like this:
STEP 3: The buzzard image has been pasted directly into the centre of the landscape, so let’s move him into the sky portion using the Hand Tool. You can also scale and rotate the image if you wish, however for the purpose of this demo he is roughly the right size. With the buzzard positioned where you want him, change the Blend Mode of the buzzard layer to Multiply.
STEP 4: Double-Click on the buzzard Layer, anywhere towards the right-hand side of the layer, as illustrated here. This brings up a new panel called Layer Style.
LAYER STYLE
At the top of the Layer Style panel are a number of Blending Options, and it is in this area that we will be working on. From the illustration below, you can see that you can change the Blend Mode, Opacity, Fill, as well as selectively blend on individual RGB channels. What we are interested in however is the two Gradient Bars at the bottom of the panel.
These target tones whereby, you can either select the individual RGB channels or the entire image. To apply globally to the whole image you select ‘Grey’ from the ‘Blend if’ pull-down menu. For RGB you respectively select those options from the ‘Blend if’ menu.
You can choose to change the Blend Style of both the layer you have selected (designated ‘This Layer’), and/or the layer below your selected Layer (designated the ’Underlying Layer). The Gradient Bar works by clipping tones progressively from Black or White using the Adjustment Pins at each end of the Gradient Bars.
STEP 5: Select Grey from the ‘Blend If’ pull-down menu. Now, because the areas we want to eliminate from the buzzard image are the highlights, we want to use the clipping Adjustment Pin at the right-hand side of the Gradient Bar, and slide that progressively towards left. We need to do this on the Gradient Bar labelled ‘This Layer’.
When you do this, just gradually move the Adjustment Pin until the point that the background portions around the buzzard disappear. The setting I ended up with is illustrated above.
STEP 6: Now, when you use this method, you can end up with a harsh transition line on your blended image. In this case there isn’t, but as a matter of course I refine the blend at the transitions by selecting ‘Option’ (on a Mac) or ‘Alt’ (on a PC) whilst clicking the Adjustment Pin. This splits the pin into two, as illustrated here, and allows for fine adjust of the transition. When you are happy with the Adjustment select OK to close the Layer Style Panel.
You can see that we have now done a really good job of masking the background around the buzzard, and we haven’t lost any detail from the bird as we would have invariably done using a Selection. But, we have lost a little contrast as the bird has blended with the background.
STEP 7: From the Layers Tab select ‘Create New Fill Or Adjustment Layer’ using the icon at the bottom of the panel, and then selected ‘Brightness/Contrast’.
This creates a new Layer and opens the associated Properties Panel to adjust the Brightness & Contrast of that Layer.
I adjusted the Brightness and the Contrast as illustrated here, and then closed the panel using the ‘>>’ icon at the top-right hand side of the panel.
You will notice that this has globally adjusted the contrast across the entirety of our blended image, and to be quite honest, I kind of like the change, because the landscape image lacked a little brightness anyway. We can however apply the filter adjustment locally using the little Mask that is created whenever we add a Fill/Adjustment Layer, so let’s go ahead and do this for the purpose of demonstrating the technique.
STEP 8: Selected the Mask on the Brightness/Contrast adjustment layer, as illustrated here, which shows the two brackets around the Mask icon.
Now, if you remember, black in a mask indicates those areas that are blocked from passing through the Layer, and white indicates the areas that are allowed through the Layer. Our mask here is pure white, hence our Brightness/Contrast effect is being applied globally to the whole image. We need therefore to invert the mask. We do this with ‘Command I’ (on a Mac) or ‘Control I’ (on a PC). Alternatively you can go through the Applications Bar using ‘Image > Adjustments > Invert’.
STEP 9: Double-click the Mask on our Brightness/Contrast Adjustment Layer, then make a Selection Mask around the buzzard. When you are happy with the selection commit the change by pressing OK.
EXAMPLE 3: WHERE THERE’S FIRE THERE’S SMOKE! (SCREEN BLEND MODE)
This demo uses the exact same principles we used in Section 5.5, the only difference here is the type of Blend Mode. So, rather than a full guided work-flow, here is a very quick visual demonstration.
There are occasions when you want to photographically composite images together where your source image has a very dark background and a very bright object. This is the exact opposite of the scenario in Section 5.5 where our source image was on a bright background, but the object itself was darker. This is where the Screen Blend Mode comes to our rescue!
Let’s say we want to composite this smoke with the bonfire.
In this case, we would work in the exact same way as we did in the previous example and paste a copy of the smoke onto its own Layer above our picture of the fire. Then, instead of setting the blend mode to Multiply, we use Screen. What this does, is hide all the pure black tones in our source file as it merges them with the destination.
After pasting the smoke onto its own Layer, I set the Blend Mode to Screen, and then lowered the opacity slightly to soften the effect of the blend. I then rotated and sized the smoke layer into position.
Here we used smoke that had been isolated in an image on a black background, but the principle of Screen Mode works with any object that is on a darker background. Another example is if you have a signature file on a black background, you can use Screen Mode to blend your signature file to your image. Alternatively of course if it is on a White background just use Multiply Mode.
EXAMPLE 4: Adding Edge Sharpness To An Image (SOFT LIGHT BLEND MODE)
Adding Edge Sharpness is a way to fool the eye into thinking that an image is sharper than it actually is. It achieves this by adding contrast to any edges in the image to give the impression of sharpness. To demonstrate this technique, we will use a picture of an otter, because sharpening animals with fur or feathers is an ideal use for this technique.
STEP 1: With the image opened in Photoshop, and working from the Layers Tab, duplicate the background Layer by dragging it over the ‘Create A New Layer’ icon. You can also go through the Application Bar, and ‘Layer > Duplicate Layer’.
STEP 2: Convert the new Layer into a Smart Object through the Application Bar and ‘Layer >Smart Objects > Convert To Smart Object’. This means that any effects we apply will be non-destructive. Or more specifically, when we add sharpness, we will be able to edit the effect afterwards if we need to.
STEP 3: From the Application Bar select ‘Effect > Other > High-Pass’.
What this does is turn everything in the image to a 50% grey value, with the exception of any edges it finds. On the edges it brightens and darkens the transitions.
The High-Pass pop-up window has a Radius control in it. This modifies how the Filter is applied by controlling what Photoshop considers to be an edge.
The trick when applying this Filter is to increase it only to the point that it is picking up actual edges on the object you want to sharpen. If you take the control too far up, Photoshop will start sharpening the background, which is exactly what we don’t want as things will start to look odd.
For this image, I found that a value of 6 was about right. I recognize its not so easy to see from the image above, but hopefully you can see that the sharpening is only being applied to the foreground elements. Once happy with the effect, I went ahead and pressed OK to commit the change.
STEP 4: Set the Blend Mode for the Layer to Soft Light. The advantage that we have now is that you can double click on the icon for Smart Filters in the layer panel and make further adjustments to the effect if you want to.
EXAMPLE 5: BLEND MODE MASKING A PORTRAIT ONTO A NEW BACKGROUND (OVERLAY BLEND MODE)
This demo uses the same principles we have used throughout this Chapter, the only difference being the type of Blend Mode. So, rather than a full guided work-flow, here is another very quick visual demonstration.
This technique is used a lot in Photography, in particular with studio portrait shots that have been photographed on neutral backgrounds. As an example, let’s say we want to put a background texture behind this portrait.
Working in the exact same way as before, we would open up the portrait, and then create a new Layer above it. Then we copy and paste the texture into the new Layer. Now, we set the blend mode to Overlay. Note that Soft Light also works when using this blending technique, you basically use the mode from the two which looks the best! You then end up with something that looks like this:
Ok, so right now this isn’t going to be a look which our model is going to be happy with, but we are not finished quite yet. We then create a Mask Layer on the texture Layer, and then double-click the Mask Layer to access the Masking Workspace. We then use the brushes in the workspace to make a rough selection of the model. You don’t need to worry so much about the fine details around the hair, because the eye will not notice that there is a slight texture in the fine details. The important thing is to get the main elements of the body. Once you are happy with your masking you click OK to commit the change.
TOP TIP: If you find your resultant image lacks contrast, create a duplicate layer of the portrait, and set the blend mode of that to Soft Light for an instant contrast boost!
