Brightness / Contrast

Brightness / Contrast is a Fusion Color Tool that processes a normal 2D RGBA image. It does not generate an image by itself and it is not a mask generator: the primary source enters through Input, while the blue Effect Mask only limits the spatial contribution of the completed correction.

A defining property of the tool is its fixed processing order. Blackmagic's Fusion Tool Reference states that the controls are arranged in the order in which the operations are applied: Gain precedes Lift, Lift precedes Gamma, then Contrast, Brightness and Saturation.

The current Resolve capture starts with R, G, B and A switches. These choose which components participate in the internal Brightness / Contrast processing. They are component switches, not qualifiers that select red, green or blue objects in the picture.

The bundled target-build capture shows RGB enabled and A disabled. Treat that as UI evidence for the captured build, not as a universal default across every Fusion version; production templates should set channel state explicitly.

Gain multiplies pixel values. Its effect is therefore more obvious in the middle and upper ranges than near zero, and it can easily create values above 1.0 in a floating-point pipeline.

Lift is not another generic brightness knob. In the classic Fusion model it affects the lower range more strongly while leaving the white end comparatively stable, making it useful for removing gray contamination from a utility map or lifting low values.

Gamma changes the midrange nonlinearly. Black and white endpoints move much less than mid-gray, so a grayscale ramp is a better diagnostic source than a single arbitrary shot when learning Gamma behavior.

Contrast expands or compresses tonal separation. Raising it pushes midrange values farther toward black and white; lowering it compresses the range toward the middle. This makes Contrast especially useful for procedural mattes and utility textures.

Brightness adds a linear offset to pixel values. That is mathematically different from Gain, so matching numerical changes in Gain and Brightness do not produce the same response in shadows and highlights.

Saturation controls RGB colorfulness after the preceding tonal stages. A value of zero produces grayscale. On purely monochrome utility data it may be irrelevant, but on a color branch it remains part of the same ordered correction pipeline.

Low and High are range-remapping controls, not Clip Black/White and not a binary Threshold. The classic reference describes lowering High with Low anchored at zero as gain-like expansion, while raising Low with High anchored at one pushes more values toward black.

Because Low/High reshape the range, aggressive settings can destroy useful gray falloff. If downstream Displace, Glow, Bitmap or compositing depends on continuous values, inspect a ramp or waveform before making the map harder.

Direction offers Forward and Reverse. Forward applies the current correction normally; Reverse is intended to apply the inverse form of the same correction values farther downstream. It should not be treated as a generic image Invert or as an undo for unrelated tools.

Blackmagic specifically recommends floating-point processing for the best Forward/Reverse behavior. A practical verification is a matched pair: one Brightness / Contrast in Forward followed by another with identical values in Reverse.

Clip Black and Clip White deal with out-of-range floating-point values. Clip Black removes values below 0; Clip White removes values above 1. These switches can make a signal safer for some downstream operations but permanently discard data that a later Reverse stage cannot reconstruct.

Historical documentation ties Clip Black/White primarily to floating-point processing because integer-depth images do not preserve the same out-of-range headroom. In a modern HDR, linear or utility-data workflow, still verify the actual bit depth and signal range instead of assuming clipping is harmless.

Pre-Divide / Post-Multiply is the alpha-safe option for premultiplied RGBA. RGB is divided by alpha before correction and multiplied by alpha again afterward, reducing dark or colored fringes on translucent titles, logos, keyed elements and rendered objects.

Pre-Divide / Post-Multiply does not repair bad matte geometry. Noise, holes, spill or incorrect alpha edges require their own matte/key workflow; this switch addresses RGB/alpha math order rather than rotoscoping or key cleanup.

Effect Mask controls spatial coverage after the image operation. It does not feed Low/High values and it does not replace the A-channel switch. Spatial coverage and component processing are separate decisions.

For procedural maps, leave A untouched unless transparency is intentionally part of the data. For real RGBA graphics, inspect alpha deliberately because changing A can be either useful or destructive depending on the branch.

Placed before Glow, Brightness / Contrast changes the light source rather than the halo itself. Shape source energy first, then tune halo size and intensity inside Glow so clipping and core definition remain easy to diagnose.

Placed before Bitmap or another threshold-like stage, the node is useful for preparing a grayscale range. Its Output is still an RGBA image stream, however; it does not automatically become a blue mask stream merely because the picture looks monochrome.

The small Inspector makes the tool excellent for controlled A/B testing. For tonal ranges, hue isolation, selective color, matching or more complex grading, move to Color Corrector or Color Curves rather than building a maze around Brightness / Contrast.

The bundled screenshot is the current UI-evidence boundary: RGBA switches, Gain, Lift, Gamma, Contrast, Brightness, Saturation, Low/High, Forward/Reverse, Clip Black/White and Pre-Divide/Post-Multiply are visible. Pivot, Alpha Gain, a separate Clamp and Blend are not visible and should not be documented as current controls without separate evidence.

Before publishing numerical presets, verify the target Resolve build, bit depth, upstream color state and premultiplication. The basic control math is historically stable, but the visible result still depends on the surrounding pipeline.