Dither

Dither adds random noise to an image to hide color quantization effects. Color quantization is a reduction in the number of colors used in the image, and can occur, for example, if the image has been stored into an 8-bit file without error diffusion. In a dithered image, colors that are not available are approximated by a diffusion of colored pixels from within the available palette. The human eye perceives the diffusion as a mixture of the colors within it. This produces an impression of a larger number of colors and eliminates banding artifacts.

See also Noise, Grain, ScannedGrain, and F_ReGrain.

Inputs and Controls

Connection Type	Connection Name	Function
Input	unnamed	The image sequence with unwanted color quantization effects.
mask	An optional image to use as a mask. By default, the dither effect is limited to the non-black areas of the mask. At first, the mask input appears as triangle on the right side of the node, but when you drag it, it turns into an arrow labeled mask. If you cannot see the mask input, ensure that the mask control is disabled or set to none.

Connection Type

Connection Name

Function

Input

unnamed

The image sequence with unwanted color quantization effects.

mask

An optional image to use as a mask. By default, the dither effect is limited to the non-black areas of the mask.

At first, the mask input appears as triangle on the right side of the node, but when you drag it, it turns into an arrow labeled mask. If you cannot see the mask input, ensure that the mask control is disabled or set to none.

Control (UI)	Knob (Scripting)	Default Value	Function
Dither Tab
channels	channels	all	The effect is only applied to these channels. If you set this to something other than all or none, you can use the checkboxes on the right to select individual channels.
amount	amount	0.1	Up to 0.5 of this amount is added or subtracted from each pixel to create the effect. Higher values produce more dither and vice versa.
monodither	monodither	disabled	When enabled, the same dithering pattern is used for all channels.
seed	seed	1	The same pattern is usually produced for each Dither node. Changing the seed number produces a different pattern, for instance if you’re using multiple Dither nodes.
static seed	static_seed	disabled	When enabled, the dither pattern remains the same for every frame producing a constant dither effect.
mask	N/A	disabled	Enables the associated mask channel to the right. Disabling this checkbox is the same as setting the channel to none.
mask	maskChannelInput	none	The channel to use as a mask. By default, the dither effect is limited to the non-black areas of this channel.
inject	inject	disabled	Copies the mask input to the predefined mask.a channel. Injecting the mask allows you to use the same mask further downstream.
invert	invert_mask	disabled	Inverts the use of the mask channel so that the dither effect is limited to the non-white areas of the mask.
fringe	fringe	disabled	When enabled, only apply the effect to the edge of the mask. When disabled, the effect is applied to the entire mask.
(un)premult by	N/A	disabled	Enables the associated channel to the right. Disabling this checkbox is the same as setting the channel to none.
(un)premult by	unpremult	none	The image is divided by this channel before being processed, and multiplied again afterwards. If you are using premultiplied input images, you may want to check (un)premult by and select rgba.alpha here. This will simulate applying the dither before the premultiplication was done. It is the same as adding an Unpremult node before this node and a Premult node after, but allows you to work faster if you’re only using one Dither node. If you are using unpremultiplied input images, you should leave this set to none.
invert	invert_unpremult	disabled	Inverts the use of the (un)premultiply channel.
mix	mix	1	Dissolves between the original image at 0 and the full dither effect at 1.