PFM Pixel Map for Display Output

Last updated 13 November 2026

Load a PFM pixel map into a display output to tell Backstage which content pixel goes to which output pixel. This is the step that makes non-planar LED screens work: curved panels, faceted walls, domes, and any screen where the number of physical pixels and their positions vary across the surface. The pixel map is an image file — typically a 32-bit float PFM — whose red and green channels carry the normalized UV coordinate (0–1) each output pixel should sample from the content.

Before you start

  • A display surface and a display output exist in your project and the output is routed — see Create a Display
  • You have a pixel map file that describes where every output pixel samples its content. Red = horizontal coordinate, Green = vertical coordinate, both normalized to 0–1. A negative blue value marks unused pixels (no LED at that position). For a float PFM, the blue channel's magnitude is the panel index — a whole number identifying which physical LED panel the pixel belongs to.
  • The image resolution matches the display output resolution — one pixel in the image for each pixel on the output.

Use a 32-bit float PFM file. An 8-bit image (PNG, BMP) has only 255 coordinate steps across its width, which produces visible stepping on a large output. PFM gives full floating-point precision per pixel. Backstage accepts any image format it can load (PFM, PNG, BMP, DPX, TGA, TIFF), but PFM is the recommended choice. A float PFM also enables per-panel and per-seam corrections after import.

Steps

1. Open the LED Panel Correction window

The pixel map is loaded through the LED Panel Correction window — this is where you load a pixel map and, optionally, correct it by adjusting individual panels, seams and pixels on top of the loaded mapping.

Select the display output in the Outputs tree. In the Inspector, expand the LED Panel Correction section and click Open LED Panel Correction.

Alternatively, open it from View > Other Windows > LED Panel Correction and pick the output from the dropdown at the top of the window.

2. Import the pixel map

Click Import Image... in the toolbar. Browse to the PFM file and confirm.

Backstage reads the file in the background, so the window stays responsive during the import. Once loaded, the toolbar shows the image resolution, bit depth, and — for a float image — the number of LED panels detected from the blue channel.

3. Verify the result

The canvas in the LED Panel Correction window shows a live preview of the mapped output. Content should now appear correctly distributed across the physical LED positions. Pixels marked as unused in the pixel map (negative blue channel) show no content.

Reload and remove

  • Reload — re-reads the same file from disk. Use it to retry when a file was missing, or to force an immediate update. Most of the time you do not need this: Backstage watches the file and reloads it automatically when it changes on disk.

  • Remove — drops the pixel map from this output entirely, along with any corrections layered on it. If the output also has mesh warping enabled, the warp stays — the two are independent.

Both actions are undoable.

Common Mistakes

  • Using an 8-bit image for a large output — 255 coordinate steps across the width produces visible banding. Switch to a 32-bit float PFM.

  • Trying to load a pixel map on a projector output — this feature is for display outputs only. The LED Panel Correction section does not appear on projector outputs. Projectors use mesh warping instead.

  • File not found after moving the project to another machine — the project stores the file path. If the pixel map is not at that path on the new machine, the output shows "not loaded" in amber. Copy the file to the same path, or click Import Image... to pick the file from its new location.

  • Using a single-channel (grayscale) PFM — a grayscale PFM replicates the red channel into all three, so the red and green channels carry the same value. This means horizontal and vertical coordinates are identical, which is not a valid pixel map. Use a three-channel (colour) PFM with distinct red and green values.

Tips

  • The pixel map and mesh warping are independent. A display output can carry either, both, or neither. When both are present, the mesh warp applies on top of the pixel map.

  • Backstage watches the file on disk. If your mapping tool regenerates the PFM, the output updates automatically without pressing Reload.

  • Corrections (panel offsets, seam offsets, per-pixel adjustments, brightness) are layered on top of the loaded pixel map and never written into the file. Reloading or regenerating the PFM preserves all corrections.

  • The file path is saved with the project. As long as the file is accessible at that path, the pixel map and its corrections are restored automatically when the project loads.

LED Panel Correction — fine-tune panels, seams and individual pixels of an already loaded pixel map.

Create a Display — create the display surface and output that the pixel map is loaded into.

Pin a Pixel Map Raster Mapping on a Display — controls which UV mapping's coordinate space the pixel map's coordinates are relative to. The Pixel Map Raster is set on the display surface; the PFM pixel map loaded here is set on the display output.

Configure Projector Warping (Mesh Warp) — mesh warping on projector and display outputs, independent of the pixel map.

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