Bitmap

Bitmap does not draw geometry like Rectangle or Polygon. Its mask values come from the incoming image: noise, alpha, a luminance map, an EXR pass or another RGBA/technical source.

The core mental boundary is image stream in, mask stream out. The Image input carries color or auxiliary data; Bitmap output is scalar coverage used to control another operation.

A fully opaque black frame has black luminance but white Alpha. Channel = Alpha on an ordinary opaque texture therefore produces full white coverage; use Luminance or an appropriate color channel when brightness is the intended source.

Blackmagic's detailed Bitmap Mask reference documents Red, Green, Blue, Alpha, Hue, Saturation, Luminance and auxiliary coverage sources. The bundled current capture confirms the Channel control and Alpha selected, but not the entire open menu, so the exact target-build list remains a live check.

Low and High define the working conversion range. The tool reference describes Low as clipping values below the threshold to black and High as forcing values above the threshold to white; the bundled capture confirms separate Low/High controls plus enabled Clip Black and Clip White.

Do not force every Bitmap mask into a binary key. Gray values are valid partial coverage and are often the point of smoke, soft reveals, local grading and procedural transitions.

Evaluate Clip Black and Clip White together with Low/High. Change one boundary at a time on a grayscale ramp; otherwise it becomes impossible to separate threshold behavior from later Soft Edge or Level changes.

Level scales mask coverage. It is not a node bypass: Level = 0 produces black coverage, while physically disconnecting a mask wire from the receiving tool may instead let the downstream effect act across the full frame.

Soft Edge feathers an already-derived mask and does not replace tonal Low/High work. A large feather only blurs a wrong threshold if the source range was chosen incorrectly.

Filter is part of the common mask controls and changes edge filtering. The bundled current capture shows Fast Gaussian selected; the historical Blackmagic tool reference documents Box, Bartlett, Multi-box and Gaussian. The version difference is recorded rather than hidden.

Invert reverses mask polarity after channel extraction. Establish a correct non-inverted matte first, then use Invert; otherwise a wrong Channel can be mistaken for the intended opposite coverage.

Fit Input handles source/mask dimension or aspect mismatches. The real dropdown bundled with this project confirms Crop, Stretch, Inside, Width, Height and Outside.

Crop does not guarantee that the entire source remains visible: smaller sources are positioned inside the generated mask and larger sources can be clipped at the mask boundary. Center determines where that placement occurs.

Stretch independently fits X and Y and can distort aspect. Inside, Outside, Width and Height use different proportional fit rules; they are geometry controls, not tonal threshold controls.

Center is 0.5/0.5 in the bundled capture. It positions the source within the mask frame and is not a substitute for Tracker or Planar Tracker when the source must follow motion over time.

Use Object and Use Material only make sense when the input actually contains Object ID or Material ID data. Toggling them does not create semantic segmentation for a normal PNG or video clip.

The current Image capture confirms Output Size = Default / Custom / Source and Clipping Mode = None / Frame. Output Size defines the mask raster/domain while Fit Input defines how the incoming image sits inside that frame.

Clipping Mode is a domain-of-definition edge behavior, not a crop of the final program image. Test it where a soft mask reaches a frame boundary or where downstream processing requires edge samples.

Bitmap is not always mandatory: Blackmagic documents direct image-to-mask connections for tools that can select a mask channel themselves. Bitmap earns its place when explicit channel, range, clipping, softening/inversion, fitting or specialized mask-port routing is required.

Keep the image and mask branches conceptually separate. The source plate continues through its own image chain while Bitmap generates control coverage for another operation.

For production QC keep Mask Output in a dedicated Viewer until the mask is stable. Looking only at the final composite can hide a wrong Channel, fit or clipping choice.

The three bundled captures anchor this article to the actual Inspector: Controls, the open Fit Input menu and Image. Old article entries such as Post Multiply Image and Paint Mode/Combine are intentionally not presented as Bitmap's own verified controls because the current captures do not show them that way.