Output Warping

Last updated 31 August 2026

Apply image warping to an output to compensate keystone or adjust the image in blended projections.

The Output Warping window deforms one output's image on a picture of that output, by dragging a grid of control points. It drives a projector or a display output. Open it from View > Other Windows > Output Warping, or with Open Mesh Warping Window in an output's Inspector — opening it switches that output's warp on.

Control strip, first line

Control	What it does	Values / Range
Output	The output being warped. Lists every projector plus every display output. Picking a display output that carries no warp creates one. Reads Select output while nothing is picked.	Dropdown
Edit	Switches mesh warping and control-point editing on for this output. Projector outputs only — a display output's warp is either present or absent, and an absent one is not in the Output list. With Edit off, the mesh source and file controls on the second line are unavailable.	Checkbox
Grid	Control points across the output, horizontally then vertically. The two fields are labelled Horizontal points and Vertical points in their tooltips.	`3`–`1000` each, default `7` × `5`
Reset …	Resets the warp. The label and the target change with what is being edited — see the table below.	Button
Point Size	Size of the control-point markers drawn on the output. A server-wide preference: it applies to every output's overlay, not only the one being edited.	`0.5`–`3.0`, default `1.5`

The reset button carries three labels:

Label	When it appears	What it resets
Reset Grid	No control points selected	The whole control-point grid, back to its default positions
Reset Selected	One or more control points selected	Only the selected control points
Reset Keystone · Reset Cylinder · Reset Toroid	The base-shape toggle in the canvas toolbar is on	The base handles, flattened back to planar. The grid's own warp is kept

Control strip, second line

Control	What it does	Values / Range
Preset	The warp set this output is using. Selecting the entry after the last existing preset creates it. Switching preset drops the current selection, since the points belong to the preset being left. Projector outputs only.	Dropdown, Preset 1 upwards
i (guidance badge)	Hover shows the in-window guide to the warp modes, the toolbar icons, grid editing, handle editing and the view gestures. Projector outputs only.	Hover
Mode	The base shape the warp grid is built on — see Mode below.	Dropdown
Projector	Switches projector editing on: the arrow, Page Up/Page Down and Q/W/E keys then move, rotate or adjust the lens of the projector in the scene while you watch the output. A read-only readout of position, rotation, lens shift and throw ratio appears on the canvas with the active mode highlighted. Projector outputs only.	Checkbox, default off
Select File	Opens the file dialog for the camera-calibration mesh. Its tooltip carries the load state: No file selected, Loaded file <name> or Failed loading <name>. Projector outputs in Calibrator mode only.	Button
Reload	Re-reads the selected calibration mesh file. Same tooltip as Select File. Projector outputs in Calibrator mode only.	Button
Import Mesh...	Imports a warp mesh file. The imported grid replaces the geometry: the base handles go back to flat and Mode back to Planar. Not undoable. Available in Planar, Cylindrical and Toroidal modes, for both output types.	Button
Export Mesh...	Writes the current warp mesh to a file, to reuse it on another output or machine. Available in Planar, Cylindrical and Toroidal modes, for both output types.	Button

A generated warp mesh is tied to the routing. Un-routing a projector from an output discards it. Export Mesh... before un-routing, and import it again after re-routing, or the alignment is lost.

Mode

The grid's control-point warp is applied on top of the chosen base.

Mode	What it is	Base handles	Availability
Planar	Flat output, with an optional 4-corner keystone.	4 — TL, TR, BL, BR	Projector and display outputs
Cylindrical	Curved top and bottom edges — a curved wall.	6 — the four corners plus TC, BC	Projector and display outputs
Toroidal	Curved on all four edges — a dome or doubly-curved wall.	8 — the six above plus LC, RC	Projector and display outputs
Calibrator	Mesh from a camera calibration, selected with Select File.	None	Projector outputs
MPCDI	Mesh imported from an MPCDI file.	None	Projector outputs

LED Panel Correction

A separate window, on display outputs only, opened from View > Other Windows > LED Panel Correction, with Open LED Panel Correction in a display output's Inspector, or with the warp icon beside a display output in the video routing list — on a projector that same icon still opens Output Warping. An imported correction image gives, per pixel, the coordinate to sample the display surface's mapping at, in its red and green channels — the measured geometry of the LED panels.

It composes with mesh warping rather than replacing it: the warp grid addresses the image, so an unwarped grid leaves the imported mapping exactly as authored, and dragging a control point moves that mapping with it. The two are switched on independently — an output can carry either, both or neither — and opening this window switches no warp on.

Control	What it does	Values / Range
Select output	The display output to correct. None closes the correction.	Combo
Import Image...	Imports the correction image. Undoable.	Button
Correction image:	What was decoded, as `width x height, N bit/channel, N panels` — the depth actually decoded, which is not always the file's, and how many LED panels the image's third channel resolves to. Shown in the warning colour, reading not loaded, when there is a path but no image. The full file path is in the tooltip. The row appears once a file has been imported or a path restored with the project.	Read-only
Reload	Re-reads the same file. Not an undo step, since the state does not change.	Button
Remove	Drops the correction image. Mesh warping, if the output has any, stays.	Button

Correcting the imported image

The image's third channel is the LED panel each pixel was measured on, so a correction can be nudged a whole panel at a time instead of pixel by pixel. Negative marks a pixel the mapping does not use; those cannot be selected and are never moved.

The seams between panels are found from the same channel and can be corrected on their own, which is where a wall's visible artefacts usually sit. A seam is one pixel deep — the boundary line itself — and belongs to one panel: a panel's seam facing its neighbour and that neighbour's seam facing back are two separate things, so correcting one moves only that panel's border pixels. A panel's outward-facing sides, at the edge of the wall, are one seam of their own.

Authoring needs a 32-bit float PFM. A narrower image is still shown and still corrects the output, but keeps no per-pixel data, so the controls below are disabled and the strip reads Import a 32-bit float PFM to correct pixels.

Control	What it does	Values / Range
Pixel / Panel / Edge	What a click on the picture picks: the one pixel clicked, every pixel the image assigns to the same panel, or the seam that panel shares with the neighbour clicked towards. Changing mode clears the selection.	Combo
Show panels	Outlines every panel the image describes, tinted by index. A diagnostic: an image whose third channel is not panel indices shows up here as a nonsense layout rather than misbehaving silently.	Checkbox
U / V	In Pixel mode, the coordinate the selected pixel now samples — the imported value plus any correction. Dragging moves one image pixel per mouse pixel; a value can also be typed.	Drag, 5 decimals
U offset / V offset	In Panel mode, the correction applied to every pixel of the selected panel; in Edge mode, the correction applied to the selected seam. Absolute, so repeating a drag does not accumulate; zero means no correction.	Drag, 5 decimals
Brightness	How bright the selection runs. In Panel and Edge mode the selection's own factor; in Pixel mode the value the selected pixel actually runs at, which is its panel's factor and its own combined. 100% is untouched, and above 100% is allowed — a panel can be the bright one on a wall trimmed down elsewhere.	Drag, 2 decimals, % — 0 % and up
Reset Panel	In Panel mode. Drops the selected panel's correction and brightness, its seams', and any single-pixel corrections inside it.	Button
Clear Corrections	Drops every correction authored here, leaving the imported image as it loaded.	Button

Corrections are layered on top of the imported image, never written into it, so a regenerated calibration picked up by Reload does not erase them. A single-pixel correction therefore still travels with its panel when the panel is moved afterwards. If the regenerated image has a different resolution, the per-panel corrections are kept and the per-pixel ones are dropped — a panel survives a re-render, a pixel index does not.

Brightness follows the same rules, and composes by multiplying rather than adding: pulling a panel down takes the hand-tuned pixels inside it with it, in proportion, instead of flattening them towards each other. A pixel a panel does not use shows nothing to make brighter, so it cannot be given a brightness of its own.

A pixel at a panel corner is on two seams and takes both of their corrections: the two offsets are added, so closing both seams moves it diagonally, while its brightness is the darker of the two rather than the two multiplied — a product would leave a dark dot at every panel corner. Clicking a corner picks the seam facing the neighbour the click points towards.

Seam corrections are keyed by the two panels they lie between, so they follow the per-panel rule rather than the per-pixel one: a calibration regenerated at a different resolution keeps them. A seam the re-panelled wall no longer has is dropped.

The selection is per window and is not saved with the project; the corrections themselves are. A whole drag is one undo step.

Navigating the picture

Pixel mode on a large correction is aiming at a fraction of a screen pixel at fit size, so the picture zooms. The Fit / Zoom / Pan overlay in the top-right corner is the same one the warp canvas uses, and so are the gestures:

Gesture	What it does
Ctrl + Wheel, or pinch	Zooms toward the cursor — the content under the pointer stays under it
Wheel	Pans vertically
Shift + Wheel	Pans horizontally
Middle-drag	Pans
Overlay top button	Back to the fitted view

Zoom runs from 0.1 upwards, and how far up depends on the correction: enough for one imported pixel to cover about 8 screen pixels, so a pixel can always be picked whatever the image's resolution — roughly 107x for a 7680-wide correction in a default-width window, and the familiar 4.0 for anything small enough to reach its pixels sooner. The pan is limited with the zoom, so the picture cannot be dragged out of the window. Zooming re-renders the output at the zoomed size rather than magnifying the fitted picture, capped at the output's own resolution — past one canvas pixel per output pixel there is no more detail to show. The view is per window, is not saved with the project, and resets when the window is closed or pointed at another output.

The window shows the output it corrects, letterboxed the same way as the warp canvas above. The picture exists only while the window is open.

While a file is being read the picture is veiled with a turning progress indicator and the status reads reading..., because the output still shows the previous correction until the new one is ready. The import controls are unavailable until it finishes. A large image stays responsive: only the final hand-over pauses the window, not the reading and unpacking.

A regenerated image on disk is picked up on its own, about a second and a half after the last write, and stays as responsive as an interactive import — Reload is for retrying a file that was missing, or forcing a re-read now. If the file is still being written when that happens the read fails, the status reads not loaded, the previous correction is kept, and the next write picks it up.

A file the machine does not have, or one that fails to decode, is a warning, not an error: the output keeps whatever else it has, the path is retained so Reload can retry, and the status reads not loaded. Nothing is substituted for the missing image.

PFM is the format to use. An 8-bit image carries only 255 steps across its width, a visible step of about 7.5 px on a 1920-wide output; a 16-bit PNG does not fix it, because it is decoded to a packed 10-bit word, about 1.9 px.

Canvas

The picture of the output fills the window, letterboxed to the output's aspect ratio and dimmed outside it.

Drawn	Meaning
Rectangle at the image border	The output's limit. Coloured by the scene projector driving it; white for a display output
Round dots, joined by thin lines	Grid control points and the lattice between them. White, and red once selected — both colours are server-wide preferences
Blue squares labelled TL TR BL BR TC BC LC RC	The base handles, drawn while the base-shape toggle is on. The selected or dragged handle turns red
Amber outline	Where the base's four edges sit from the handles alone, without the grid's adjustments. Drawn once the handles have been moved off flat
Green ring under the cursor while Ctrl is held	Control points that a click would add to the selection
Orange ring under the cursor while Ctrl is held	Control points that a click would remove from the selection
Text panel at the image centre	The projector readout, while Projector is on: position, rotation, lens shift and throw ratio

Navigation overlay

Three circles at the window's top-right corner.

Control	What it does
Fit (top)	Resets zoom and pan to fit the output in the window. Tooltip Fit view (F)
Zoom	Drag up to zoom in, down to zoom out, anchored at the image centre
Pan	Drag to move the view

Icon toolbar

Five icon buttons stacked below the navigation overlay. An active toggle is drawn in the accent colour. The first four are window-level: they apply to whichever output the window is showing and are not saved with the project.

Icon	What it does	Default
Base shape — trapezoid, cylinder or saddle, following Mode	On: drag the base handles, and grid editing is suspended. Off: drag the grid. Available even while Edit is off, so the base can be set first. Shown for Planar, Cylindrical and Toroidal	On
Spline	Curved interpolation between control points. Off is linear	On
Falloff H	Spreads an edit to neighbouring points horizontally. Off is uniform across the horizontal axis	On
Falloff V	Spreads an edit to neighbouring points vertically. Off is uniform across the vertical axis	On
Show wireframe mesh	Draws the warp's triangle mesh over the output. Per output, and projector outputs only	Off

Right-click: Selection

Right-clicking with control points selected opens a menu headed Selection.

Control	What it does
Reset Selected Points	Resets the warp of the selected points to their default positions
Remove Points	Removes the selected points. Shown in Planar, Cylindrical and Toroidal modes, and unavailable while the selection contains a point that cannot be removed

Right-click: Warp options

Right-clicking with nothing selected opens a menu headed Warp options.

Section	Control	What it does	Values / Range
Points	+ Add point	Arms point placement; the next click on the canvas places the point. A right-click cancels it. Planar, Cylindrical and Toroidal modes	Button
Keystone · Cylinder · Toroid	Reset Keystone base · Reset Cylinder base · Reset Toroid base	Resets that base's handles to the flat, planar default, keeping the grid's own warp	Button
Projector	Throw Ratio	The scene projector's throw ratio. Edits the projector, not the warp	`0.1`–`10`, step `0.01`
Projector	Lens Shift	The scene projector's horizontal and vertical lens shift. Edits the projector, not the warp	`-100`–`100`, step `0.01`
File	Export · Import	Writes or reads the camera-calibration mesh. Projector outputs in Calibrator mode only	Buttons

The Projector section appears for an output a scene projector drives.

Mouse and keyboard

Input	Effect
Click	Selects a control point, or a base handle in base-shape mode. Clicking a selected handle again begins dragging it
Ctrl + click	Adds to, or removes from, the selection. On a border point it takes the whole row or column
Left-drag	Moves the selected control points, or the selected base handle
Ctrl + A	Selects every control point
Arrow keys	Move the selection — control points, or the selected base handle. Ctrl takes a fine step, Shift a coarse one
Alt + arrow key	Moves the selection to the neighbouring control point or handle
Q / W / E	While Projector is on: pick move, rotate or intrinsics
Arrow keys, Page Up / Page Down	While Projector is on: sideways and up/down, and to-from the surface, or yaw/pitch/roll, or lens shift H/V and throw ratio
Ctrl + wheel, or pinch	Zooms toward the cursor
Wheel	Pans vertically. Shift + wheel pans horizontally
Middle-drag, or two-finger drag	Pans
F	Fits the view
Right-click	Opens the selection or the warp-options menu

Mesh Warping, in the output Inspector

Control	What it does	Values / Range
Enable UV Warp	Deforms the UV coordinates this output samples content with, so video looks correct on a physically non-planar LED display — a dome, or curved or faceted panels. Off costs nothing: no texture and no extra render pass. Display outputs only, and the only place a display output's warp is switched off	Checkbox
Open Mesh Warping Window	Opens this window on that output, switching its warp on	Button

LED Panel Correction, in the output Inspector

Its own section, on display outputs only.

Control	What it does	Values / Range
Open LED Panel Correction	Opens the correction window on that output. Switches no warp on — a correction is independent of mesh warping	Button

Display outputs

A display output carries the same warp as a projector, switched on per output with Enable UV Warp, and gets the same modes, grid, reset and mesh import and export.

Two differences: on a split display surface the grid spans that output's own display slot rather than the whole surface, so each output's control points belong to the image it actually shows; and a display output additionally accepts an imported LED panel correction, which has its own window.

Configure Projector Warping (Mesh Warp) — warping a projector onto a surface

Set up a manual panorama projection — several projectors warped and blended across a wide screen

Use Camera Calibration (CalibratorLite) — producing a warp mesh from a camera instead of by hand

GPU Output — the output the warp is applied to