ANR Black Match

Overview

Black Match moves the Foreground's black point onto the Background's. The black point is the level of the darkest few pixels of an image (Black Pick percent). The node adds the difference, Background black minus Foreground black, to the whole Foreground: one offset per channel, scaled by the Foreground's alpha, so soft edges get their share and nothing outside the element changes.

In Live mode both black points are measured on every frame, so the element follows a plate whose blacks drift: an exposure change, a flicker, haze rolling in. In Picked mode the node uses two fixed values, set by a Pick button on the frame you are on, or typed in.

Because it changes one value per channel rather than each pixel, no tracking is needed and the element's own contrast and detail stay as they are: only its floor moves. Use it for haze, flare, a lifted black level, or a CG render whose shadows are cleaner than the plate's.

Inputs

1. Foregroundrequired

   The element whose blacks move (a CG render, a patch, a keyed element), already placed over the plate. Its black point is measured where its alpha is above one half; an image without alpha counts everywhere.

2. Backgroundrequired

   The plate the element sits on. Its black point is the target, measured over the whole frame or only behind the Foreground (Background Region).

3. Maskoptional

   Limits where the offset is applied. Invert Mask applies it outside the mask instead.

Output. The Foreground with its blacks moved and its alpha unchanged, ready to merge over the plate. Output > Offset shows the offset itself as a flat colour instead.

Quick start

1. Place and grade your element over the plate as usual.
2. Add ANR Black Match. Connect the element to Foreground and the plate to Background.
3. Leave Mode on Live: on every frame the element's darkest level now sits on the plate's.
4. If the plate's darkest areas are far from the element (letterbox bars, a deep shadow on the other side of frame), set Background Region to Behind Foreground.
5. If grain makes the result flicker, raise Live Smoothing to average the measurement over a few frames either side.
6. For a fixed correction instead, go to a good frame and press Pick Blacks: Whole Background or Pick Blacks: Behind Foreground. The node keeps both black points and switches to Picked.
7. Merge the result over the plate as before.

The panel

The node's panel as Nuke shows it, with the values of a new node. Click any control to see what it does; tabs and sections work as in Nuke.

All controls

Tips

• Set Output to Offset to see the correction alone, as a flat colour.
• Channels > RGB matches each channel, so a tinted haze in the plate's blacks carries over to the element. Luminance applies one offset to all three channels, which keeps the element's own colour balance.
• Raise Black Pick when a few stray dark pixels decide the black point. At 0 the single darkest spot decides, which grain makes unreliable.
• Strength scales the offset (above 1 it overshoots); Mix blends the result with the untouched Foreground.
• After a Pick, Status shows the black points found and the frame they came from.
• In Picked mode you can type Foreground Black and Background Black yourself, or key them.

Good to know

• Whole Background measures everything in the frame: letterbox bars or a black border become the plate's black point. Use Behind Foreground for such plates, or crop the bars off the Background input.
• In Live mode, a frame where the Foreground's alpha is nowhere above one half has nothing to measure and gets no offset. For an element that fades in or dissolves, use Picked.
• Live Smoothing measures that many frames on each side for every frame it renders, so high values are slower.

Works with

ANR Light MatchKeeps a comped element's light in step with the plate: when the wall behind it brightens, darkens or flickers, the element changes the same way.ANR Interactive LightLights an element with footage of a fire, lightning or a screen, through its normals and depth, with shadows from its own shape or from smoke.