Mix Node

Blends two images together, much like how an image editing program blends two layers.

Inputs

Fac

The opacity of the foreground image.

Image

The background image. Determines the dimensions of the output.

Image

The foreground image.

Keep in mind that, unlike image editing programs where the foreground layer is on top, the foreground slot in Blender is on the bottom.

Properties

Blending Mode

The blending mode to use.

• Mix

  Regular alpha blending. Typically called Normal in image editing programs.

  Darken

  For each color component, takes the smallest of the two values being blended.

  Multiply

  Multiplies the colors component by component. Blending with a white pixel (value 1.0) has no effect, while blending with a black one (0.0) always results in black.

  Color Burn

  Inverts the background color, divides it by the foreground color, and inverts the result.

  Lighten

  For each color component, takes the largest of the two values being blended.

  Screen

  Inverts both colors, multiplies them, and inverts the result.

  Color Dodge

  Divides the background color by the inverted foreground color.

  Add

  Adds the two colors together.

  Overlay

  Applies Multiply blending if the foreground color’s lightness is below 0.5, or Screen blending if it’s above.

  Soft Light

  Like Overlay, but more subtle.

  Linear Light

  Applies Linear Burn blending (background + foregound - 1) if the foreground color’s lightness is below 0.5, or Linear Dodge (background + foreground) if it’s above.

  Difference

  For each component, subtracts the lower value from the higher value.

  Exclusion

  Adds the two colors, then subtracts their multiple twice.

  Subtract

  Subtracts the foreground color from the background color.

  Divide

  Divides the background color by the foreground color.

  Hue

  Combines the saturation and value of the background color with the hue of the foreground color.

  Saturation

  Combines the hue and value of the background color with the saturation of the foreground color.

  Color

  Combines the value of the background color with the hue and saturation of the foreground color.

  Value

  Combines the hue and saturation of the background color with the value of the foreground color.

  Use Alpha

  Whether to use the alpha channel of the foreground image during mixing. The alpha channel of the background image is always used.

Clamp

Clamp the output value to the [0.0, 1.0] range.

Outputs

Image

The result of the mixing operation.

Examples

Below are examples of blending modes, as well as some practical use cases.

Fixing overexposure

The Compositing setup below shows how to fix an overexposed render by darkening it and increasing contrast.

The top RGB Curves Node darkens the image by linearly scaling each color value to a smaller one.

The bottom curve node increases constract by making small values smaller and large values larger.

Finally, the Mix node blends the two together.

Watermark Images

In the old days, a pattern was pressed into the paper mush as it dried, creating a mark that identified who made the paper and where it came from. The mark was barely perceptible except in just the right light. Probably the first form of subliminal advertising.

Nowadays, people watermark their images to identify them as personal intellectual property, for subliminal advertising of the author or hosting service, or simply to track their image’s proliferation throughout the web.

Blender provides a complete set of tools for you to both encode your watermark and to tell if an image has your watermark.

Encoding your Watermark in an Image

First, construct your own personal watermark. You can use your name, a word, or a shape or image not easily replicated. While neutral gray works best using the encoding method suggested, you are free to use other colors or patterns. It can be a single pixel or a whole gradient; it is up to you.

In the example below, we are encoding the watermark in a specific location in the image using the Translate node; this helps later because we only have to look at a specific location for the mark. We then use the RGB to BW node to convert the color image to grayscale numbers, which we then feed into the Map Range node to reduce the mark to one-tenth of its original intensity.

The Add node (Mix node with blending mode Add) adds the corresponding pixels, making the ones containing the mark ever-so-slightly brighter.

Of course, if you want people to notice your mark, do not scale it so much, or make it a contrasting color. There are also many other ways, using other mix settings and fancier rigs. Feel free to experiment!

Decoding an Image for your Watermark

When you see an image that you think might be yours, use the node tree below to compare it to your stock image (pre-watermarked original). In this tree, the Mix node is set to Difference, and the Map Value node amplifies any difference. You can see how the original mark clearly stands out.