user: Give a detailed overview of Inputs: syntax, arguments, return values, common patterns.

assistant: Image
:   Standard color input.

Key Color
:   The color of content to be removed. This may be a single color,
    or a reference image such as generated by
    the [Keying Screen Node](keying_screen.xhtml).

### Preprocess

Blur Size
:   Reduce the effects of color noise in the image by blurring only color by the given amount,
    leaving luminosity intact. This will affect matte calculation only, not the result image.

### Key

Balance
:   This is the balance between color channels compared with the key color.
    0.5 will average the other channels (red and blue in the case of a green screen).

    This may be tweaked in tandem with *Clip Black* and *Clip White* while
    checking the *Matte* output to create a mask with optimal separation.

### Tweak

Black Level
:   This sets the threshold for what becomes fully transparent in the output (black in the matte).
    It should be set as low as possible. Uneven backdrops will require this value to be increased.
    Use of the [Keying Screen Node](keying_screen.xhtml) can help
    keep this value low. You may also use a *Garbage Matte* to exclude problematic areas.

    This value does not impact areas detected as edges to ensure edge detail is preserved.

White Level
:   This sets the threshold for what becomes fully opaque in the output (white in the matte).
    It should be set as high as possible. Colors close to green in the foreground
    may require reducing this value and/or adjusting the *Screen Balance*.
    Particularly problematic parts can fixed with a *Core Matte* instead of a low *Clip White*.

    This value does not impact areas detected as edges to ensure edge detail is preserved.

#### Edges

Size
:   Defines the radius in pixel used to detect an edge.

Tolerance
:   Defines threshold used to check if pixels in radius are the same as current pixel:
    if the difference between pixel colors is higher than this threshold then the point
    will be considered an edge.

### Mask

Garbage Matte
:   An optional mask of area(s) to always *exclude* from the output.
    This is removed from the chroma key generated matte.

Core Matte
:   An optional mask of area(s) to always *include* in the output.
    This is merged with the chroma key generated matte.

### Postprocess

Blur Size
:   Make the matte less sharp, for smoother transitions to the background and noise reduction.

Dilate Size
:   Enlarge (positive numbers) or shrink (negative numbers) the matte by the specified number of pixels.
    This is similar to using the [Dilate/Erode Node](../filter/dilate_erode.xhtml) on the matte.

    This a simple way to include more or less along the edges of the matte, particularly combined with *Post Blur*.

Feather Size
:   Controls how much the matte is feathered inwards (negative number) or outwards (positive number).

Feather Falloff
:   The rate of the falloff at the edges of the matte when feathering, to manage edge detail.

### Despill

Strength
:   Controls how much color bleed from the key color is removed from the input
    image: 0 means no despilling, 1 means all possible spilling will be removed.
    The underlying implementation is the same as adjusting the *Unspill* amount
    of the [Color Spill Node](color_spill.xhtml).

Balance
:   This controls how the color channels are compared when computing spill,
    affecting the hue and shade of the corrected colors.
    It is similar to setting the *Limiting Channel*
    in the [Color Spill Node](color_spill.xhtml).