# Blending Modes

Blending modes are a little difficult to explain. Basically, when one layer is above the other, the computer uses a bit of programming to decide how the combination of both layers will look.

Blending modes can not just apply to Layers, but also to individual strokes.

## Normal

Let's start explaining with the Normal Blending mode: As you may have guessed this is the default Blending mode for all layers.

In this mode, the computer checks on the upper layer how transparent a pixel is, which colour it is, and then mixes the colour of the upper layer with the lower layer measured by transparency.

## Arithmetic

These blending modes are based on simple maths.

Adds the numerical values of two colours together:

Yellow(1,1,0)+Blue(0,0,1)=White(1,1,1)

Red(1,0,0)+Grey(0.5,0.5,0.5)=Pink(1,0.5,0.5)

### Divide

Divides the numerical value from the lower color by the upper color.

### Inverse Substract

This, unlike regular substract, will consider 0,0,0 the lowest number.

So black(0,0,0)-grey(0.5,0.5,0.5) doesn't become grey, but stays black.

### Multiply

Multiplies the two colors with each other, but does not go beyond the upper limit.

This is often used to color in a black and white lineart. One puts the black and white lineart on top, and sets the layer to 'Multiply', and then draw in color on a layer beneath. Multiply will all the colour to go through.

White(1,1,1)xWhite(1,1,1)=White(1,1,1) White(1,1,1)xGrey(0.5,0.5,0.5)=Grey(0.5,0.5,0.5) Grey(0.5,0.5,0.5)xGrey(0.5,0.5,0.5)=Dark grey(0.25,0.25,0.25)

### Substract

White(1,1,1)-White(1,1,1)=Black(0,0,0) White(1,1,1)-Grey(0.5,0.5,0.5)=Grey(0.5,0.5,0.5) Grey(0.5,0.5,0.5)-Grey(0.5,0.5,0.5)=Black(0,0,0)

## HSI

HSI is a color coordinate system, using Hue, Saturation and Intensity to catagorise a color. Hue is roughly the wavelength, whether the colour is red, yellow, green, cyan, blue or purple. It is measure in 360°, with 0 being red. Saturation is the measurement of how close a color is to grey. Intensity, in this case is the tone of the color. What makes intensity special is that it recognises Yellow(rgb:1,1,0) having a higher combined rgb value than blue(rgb:0,0,1). This is a non-linear tone dimension, which means it's gamma-corrected.

### Color HSI

This takes the Intensity of the colours on the lower layer, and combines them with the Saturation and Hue of the upper pixels.

## HSL

HSL is also a color coordinate system. It describes colors in Hue, Saturation and Lightness. Lightness specifically puts both yellow(rgb:1,1,0), blue(rgb:0,0,1) and middle grey(rgb:0.5,0.5,0.5) at the same lightness(0.5).

### Color HSL

This takes the Lightness of the colours on the lower layer, and combines them with the Saturation and Hue of the upper pixels.

## Negative

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