LAYER BLENDING MODES - Introduction

This tutorial was prepared by Roy Killen and is copyright. It is part of the training materials provided for members of the Belmont 16 Ft Photographic Club and is not intended as a complete, stand-alone instruction package.

Comments and suggestions on this tutorial are welcome - they should be emailed to Roy Killen.

LAYERS IN PHOTOSHOP

When you open an image in Photoshop it becomes the "background" layer and you can see its icon and the word "Background" in the Layers Palette.

You can make changes directly to the Background layer (for example, by applying a Levels adjustment) but this is generally not a good idea.

It is better to make changes to Adjustment Layers or duplicate layers so that the original image is not altered and you can always revert to the original (Background) layer if you need to.

If you add a new layer of any sort it will appear in the Layers palette immediately above the Background layer. If you add further layers they will apear immediately above whatever layer was highlighted (in blue) in the Layers palette.

This example shows what happens when you duplicate the Backgroud layer and then add a Curves adjustment layer.

When there are multiple layers in an image file, what you see on the screen (and what will print) is determined by three things:

How each layer appears to modify the layers below it. For example, a Levels adjustment layer will appear to alter the black point, white point and contrast in an image layer below it even though there are no actual changes made to the image layer.

The opacity of each layer. For example, if you reduce the opacity of an image layer you will be able to "see through it" to reveal the image below.

The Blend Mode of each layer. This can have many different effects as you will see in the remainder of this tutorial.

THE NORMAL BLEND MODE

In the Layers palette, just below the Layers tab there is a small window in which the word "Normal" appears unless you change to another blend mode.

With the Normal blend mode selected the layers will interact with one another in a "normal" fashion. For example:

If the top layer is an image covering the full canvas then it will hide everything below it.
If the top layer is an adjustment layer it will appear to alter the image below it in the same way that a similar adjustment would alter the image below if applied directly to it.

For a lot of your work in Photoshop, you will keep the blend mode of each layer on "Normal". However, the other blend modes that are available open up a wide range of possible adjustments and creative options.

To reveal the other blend modes you simply click on the double-headed arrow near the word "Normal" and a list of available blend modes will appear.

THE OTHER BLEND MODES

There are 25 layer blend modes availablel in Photoshop CS3 (two new ones were added after CS2) and they are in six groups (with lines separating them on the pop-up list).

Each blend mode provides a different way of altering the colour or luminosity of each pixel in the image - depending on the colour or luminosity of the pixels in the blend layer and in the layer immediately beneath it.

Changes to the blend mode of a layer do not physically alter any of the pixels in an image - so they can be reversed so long as you keep the layers in the file.

Note: When the Background layer is selected the blend mode options are greyed out - the Background layer blend mode cannot be changed (because there is nothing below it to sample).

The list of blend modes available from the pop-up menu is shown below.

GROUP 1 - Standard modes.

GROUP 2 - Darkening modes (White neutral modes)

GROUP 3 - Lightening modes (Black neutral modes)

GROUP 4 - Contrast modes (50% grey neutral modes)

GROUP 5 - Comparison modes

GROUP 6 - Colour modes

For general photographic work, the blend modes that you will use most frequently are Normal, Multiply, Screen, Overlay, Soft Light and Luminosity. However, the other blend modes can sometimes give you just the effect you are looking for.

The effects of the blend modes will be demonstrated in two ways. First by blending two copies of the same image (as you might do if you are trying to enhance the tonal qualities of an image) and second by blending two different images (as you might do if you are trying to produce a creative composite).

BLENDING WITH A SINGLE IMAGE

The steps you will follow here are:

Open the image.
Duplicate the background layer.
Change the blending made of the duplicate (top) layer.
Add a layer mask to the duplicate layer to limit the effects to the parts of the image you want to change.
Reduce the opacity of the duplicate layer to reduce the efect if it is too strong.

The images below show the result of performing these steps with several different blend modes. For the purpose of this demonstration I will not do step (4).

Blend mode: Normal

Blend mode: Multiply

Blend mode: Multiply, Opacity 50%

Blend mode: Screen, Opacity 50%

Blend mode: Overlay, Opacity 50%

Blend mode: Soft Light, Opacity 50%

So, what is happening with these blend modes?

MULTIPLY - The colour information for each pixel in the two layers is multiplied - giving a much darker image with more intense colours. For this sampe image the effect is far too strong at 100% (or even 50%) and would have to be reduced to around 10% to give a noticable but desirable effect.

SCREEN - This multiplies the inverse of the blending and background colours - making the image much lighter. When the opacity is reduced to 50% the effect is useful on parts of the image that were originally very dark (such as the shoulder of the koala on the right).

OVERLAY - This either multiplies or screens the colours depending on the original colour of the background pixels. It darkens the shadows and lightens the highlights but not as much as the effect with Multiply or Screen.

SOFT LIGHT - When the two layers are the same, this has almost the same effect as Overlay but is slightly more subtle. In areas of the image where the blend (top) colour is lighter that 50% grey the image is lightened. In areas of the image where the blend colour is darker than 50% grey the image is darkened.

The blending modes not shown here either produce no effect or very harsh and undesirable effects when the two layers being blended contain the same image,

BLENDING TWO DIFFERENT IMAGES

When the images in the two layers are different, changing the blending mode from Normal will produce an image that is some blended version of the two images.

Whether or not you can produce a useful image as a result of this blending will depend a lot on your creativity. However, if you experiment and understand what is happening as you change the blend modes you will be able to identify some effects that are useful for particular types of images. You will also see that you can produce some useful effects by blending an image with a solid colour or a gradient.

The examples shown below are not intended to produce a "useful" image - they are just illustrating the blending effects.

Background image

Blended (top) image

Blend mode: Multiply

Blend mode: Screen

Blend mode: Overlay

Blend mode: Soft Light

You will probably agree that none of these blended images is particularly exciting. But there is more to learn.

Consider, for example, what happens if the position of the two images is swapped in the Layers palette so that the flower becomes the background layer and the blending mode changes are made to the kangaroo (top) layer.

The result does not change for the Multiply or Screen blending modes because the information from the two layers is used the same way to produce these blends. However, the result for the Overlay and Soft Light blend modes is different. For the Overlay mode, the image is lightened or darkened depending on the base (background) colour. However, for the Soft Light mode the colours are lightened or darkened depending on the colour of the top layer.Therefore, for these two blend modes the order (position) of the two layers makes a difference to the final result. The results for these two blend modes are shown below.

Blend mode: Overlay

Blend mode: Soft Light

BLENDING AN IMAGE WITH A FILL LAYER

If you experiment with blending two images so that you understand what is happening you will soon start to see some creative possibilities. One avenue worth exploring is what happens when you blend an image with a solid colour or a gradient.

For example, if we use Overlay to blend a white-to-black gradient (white at the top of the screen, black at the bottom) with the flower image from the previous example the result is:

If the gradient is changed to "radial" (white at the centre and black at the edges) then the images changes to the following:

The results achieved with this very simple blending process would be quie difficult to ahcieve in any other way.

TO LEARN MORE

A simple way to experiment with blending modes is:

Open an image in Photoshop.
Duplicate the background layer (or add a different layer above the background)
Select the top layer.
Cycle through the Layer Blending Modes by holding down the Shift key and pressing the "plus" key on the numeric keypad of your keyboard. If this does not appear to be working make sure that you have selected one of the "selection" tools from the tools palette (not one of the painting tools).
As you cycle through the blending modes take note of how each one changes the image - look for changes in colour and changes in brightness in different parts of the image.
Reverse the order of the layers in the layers palette and repeat the steps 1 to 5.

Once you start to understand how each blending mode is working you will be ready to use it to modify images that you are adjusting.

To learn more about Layer Blending Modes you can refer to this tutorial that provides a more detailed explanation of each of the 25 blend modes.

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This page last updated 25th August 2008 (RK)