Lesson 9

Blend Mode


For the most part, in the lessons thus far, we have not touched much upon blend mode. If you stack one layer on top of another in the image, the layer on top obscures whatever is beneath it. This is the default, "Normal" blend mode. To see what is beneath the top picture, you have to reduce either the Opacity or the Fill of the layer, or else you must hide the top layer completely by toggling the visibility icon.

In this lesson, you will see how to blend the top layer with the layer beneath it in various ways to achieve artistic effects. To demonstrate how blending layers works, I will use two pictures taken at the Imperial Palace in Kyoto during cherry blossom season. The effects of changing the blend mode are difficult to describe with words, so this lesson will rely heavily on example images. After I have shown what the different blend modes do, I will give some examples of how to use them to enhance your images.

When the two pictures are stacked on top of each other in the same image in Normal mode, the result is as shown (below).


Top
+
Bottom
=
Normal

Reducing the opacity of the top layer to 50% lets the bottom layer show through (below). However, this can result in quite the garbled effect, as you can see.


Top
+
Bottom
=
Normal (Opacity: 50%)

Click on the blend mode pull-down menu in the Layers palette (left). There are many different blending options from which to choose, and they all affect the layer differently. With the cherry blossom layer active and still at 50% opacity, use this menu to change the mode from Normal to Dissolve. The result is illustrated below.


Normal
Opacity: 50%

Dissolve
Opacity: 50%

What dissolve does is act upon a layer that has less than 100% opacity to scatter random speckles across the layer contents. This is called "dither." Dissolve also works on things painted upon the layer, such as with the Brush tool.

Here is the cherry blossom image with a series of butterflies painted across it using the Brush tool (right). By putting the butterflies in their own layer and setting the layer to Dissolve, the edges of the butterflies are dithered rather than sharp.

The next item on the list, Darken, compares the pixel color of the top layer with the pixel color of the bottom layer and displays only the darker of the two (below).


Top
+
Bottom
=
Darken

This effect can be used to change the color of the light pixels in an image without changing the dark pixels (below).


Top
+
Bottom
=
Darken

The next option on the list, Multiply, multiplies the pixel color values of the top and bottom layers and displays the result (below). It gives an effect similar to a double exposure. It looks rather like Darken, but instead of replacing one color with the other, it combines the two, as you can see when you use a solid color as the top layer. Any white areas in the top layer are effectively transparent in Multiply mode.


Top
+
Bottom
=
Multiply

Top
+
Bottom
=
Multiply

Color Burn mode uses the top layer to "shade" the bottom layer (below). White pixels in the top layer are ignored. This is equivalent to reducing the light exposure for a photograph, making the image darker overall.


Top
+
Bottom
=
Color Burn

Top
+
Bottom
=
Color Burn

The next item, Linear Burn, does the same thing, except that it makes the bottom image even darker (below).


Top
+
Bottom
=
Linear Burn

The Burn effect is not limited to blend mode. If you look at the toolbar, you can see that there is also a Burn tool (left). This tool makes whatever it touches darker. (The hand icon is to represent shading an object with your hand before taking a photograph of it.)


Before

After

These pictures show the result of using the Burn tool inside the area indicated by the pink circle (right).

The next section of blend mode options is headed up by Lighten. This is the opposite of Darken. The two layers are compared, and the lighter pixel color is displayed (below). In this mode, black pixels in the top layer are effectively transparent.


Top
+
Bottom
=
Lighten

Top
+
Bottom
=
Lighten

Screen mode is the opposite of Multiply mode. It inverts the colors of the top and bottom layers first before multiplying them. The result is to make the image lighter (below). This mode is often used when one wants to make part of an image appear to glow.


Top
+
Bottom
=
Screen

Top
+
Bottom
=
Screen

Color Dodge is the opposite of Color Burn. Instead of "shading" the bottom layer, it uses the top layer to increase the light exposure of the bottom layer (below). This can be particularly effective when the bottom layer is very dark and you want to brighten it. Any black pixels in the top layer are ignored.


Top
+
Bottom
=
Color Dodge

Top
+
Bottom
=
Color Dodge

Linear Dodge is a more extreme version of Color Dodge, increasing the light exposure even further (below).


Top
+
Bottom
=
Linear Dodge

Top
+
Bottom
=
Linear Dodge


Before

After
As there is a Burn tool, there is also a Dodge tool. This allows you to lighten an area of the image, as illustrated by the pictures (right).
The next section of the blend mode menu starts with Overlay. This mode combines Multiply and Screen modes. Where the bottom layer is dark, it uses Multiply mode, and where the bottom layer is light, it uses Screen mode. The effect is to make the darks darker and the lights lighter (below).


Top
+
Bottom
=
Overlay

Top
+
Bottom
=
Overlay

Soft Light is also a mode that makes darks darker and lights lighter, but it does so using a different combination. Soft Light examines the top layer and applies Burn to the dark pixels and Dodge to the light pixels (below). This gives a much more subdued blend than Overlay. This mode is frequently used when painting highlights.


Top
+
Bottom
=
Soft Light

Top
+
Bottom
=
Soft Light

Hard Light again examines the top layer and uses a combination of modes. It is the exact opposite of Overlay; it uses Multiply on the dark pixels of the top layer and Screen on the light pixels of the top layer (below). You can switch between the result of Hard Light and the result of Overlay by reversing the order of the two layers.


Top
+
Bottom
=
Hard Light

Top
+
Bottom
=
Hard Light

Vivid Light is an exaggerated version of Soft Light. It applies the same combination of effects but raises the contrast on the dark areas and lowers the contrast on the light areas (below).


Top
+
Bottom
=
Vivid Light

Top
+
Bottom
=
Vivid Light

Linear Light is another exaggeration of Soft Light. It uses a stronger Burn on the dark areas and a stronger Dodge on the light areas (below).


Top
+
Bottom
=
Linear Light

Top
+
Bottom
=
Linear Light

Pin Light gives an interesting combination. It examines the top layer. Where the top layer is extremely light or extremely dark, it lets the top layer show. Where the top layer is more neutral, it lets the bottom layer show (below).


Top
+
Bottom
=
Pin Light

Top
+
Bottom
=
Pin Light

If you're into wild and wacky or are looking for a psychedelic or surreal effect, the next section is for you. Difference mode compares the RGB values for the colors in the two layers and subtracts the darker value from the lighter value (below). Since the value of black is zero, any black areas show no change.


Top
+
Bottom
=
Difference

Top
+
Bottom
=
Difference

Exclusion mode is a more subdued version of Difference mode (below).


Top
+
Bottom
=
Exclusion

Top
+
Bottom
=
Exclusion

Hue mode applies only the hue of the top layer to the saturation and luminosity of the bottom layer (below). This can turn a regular landscape image into a fantasyland.


Top
+
Bottom
=
Hue

Top
+
Bottom
=
Hue

Saturation mode applies the saturation of the top layer to the hue and luminosity of the bottom layer (below).


Top
+
Bottom
=
Saturation

Top
+
Bottom
=
Saturation

Color mode combines the hue and saturation of the top layer and applies them both to the luminosity of the bottom layer (below).


Top
+
Bottom
=
Color

Top
+
Bottom
=
Color

Luminosity mode combines the luminosity of the top layer with the hue and saturation of the bottom layer (below)


Top
+
Bottom
=
Luminosity

Top
+
Bottom
=
Luminosity

Now, you may have looked at the resulting combinations displayed above and thought, "Ewwww, why would I ever want to do that?!" or "But what on earth is that good for...?" The answers to both questions depend on the contents of the layers and your goals for the image.

Let's say, for example, that there's one part of your image that you wish to emphasize with respect to the rest of the image. In the picture of the garden of the Imperial Palace, I may want to draw the observer's eyes to the lantern. Watch what happens when I add a layer on top of the lantern image that contains a simple black and white gradient drawn with the Gradient tool (below).


Top
+
Bottom
=
Soft Light

Top
+
Bottom
=
Lighten

You can even use an image to enhance itself. If I want to brighten the light hitting the cherry blossoms, I can take advantage of the blend mode to let the image itself do the work (below). If the effect seems too bright or strong at first, decrease the opacity of the top layer to an acceptable level.


Top
+
Bottom
=
Overlay (Opacity: 75%)

You don't have to use the entire image if there's only a certain part that you want to emphasize. In the picture (below) I used the Elliptical Marquee to select the lantern and feathered the edge by 10 pixels. Then I simply copied and pasted the selection area to a new layer and changed the blend mode.


Top
+
Bottom
=
Multiply

You can use the blend modes in combination with text to add a special touch (below). I used a font called Pristina with a 30° Drop Shadow.


Top
+
Bottom
=
Luminosity

Even the Difference and Exclusion modes, which look bizarre when used with color, can be quite elegant in black and white (below). For this image I made a circular gradient in a new layer on top of the bunny outline from Lesson 6.


Top
+
Bottom
=
Exclusion

Homework

Open a digital photograph and do one of the following three things (or all three if you're ambitious):
  • Copy and paste all or part of a different picture (or even the same picture) on top of the background and see what happens when you change the blend mode.
  • Create a new, blank layer on top of the background and use the Brush tool (or Gradient tool) to draw in the new layer. Experiment with the blend mode.
  • Use the Text tool to type a caption for the image and change the blend mode of the text layer.