OMATOOLS/OmaRAW guide

Guide / Masks and local adjustments

External image masks

Use a greyscale image to restrict supported global adjustments.

Read the full reference ↓ · All tools

On this page · full reference

Film recorded with an earlier version; the written reference is current. This lesson explains the controls and workflow. See the recording notes below for exactly what is demonstrated.

Where it is

Develop → Masks → External mask

Quick overview

  • Import a greyscale image aligned to the uncropped, unrotated source. White selects, black protects and grey gives partial coverage.
  • Connect the managed image to a supported global adjustment. Invert changes polarity; Opacity controls its contribution.
  • Replacing the shared mask affects every connection. Back up the managed mask file; preset JSON does not embed it.

In this film

Read the transcript · Download captions

  1. An image mask limits a global adjustmentWhite selects, black protects and grey gives partial coverage.
  2. Open the External mask controlsThe file must align with the uncropped, unrotated source.
  3. Choose the adjustment to restrictThis example connects the mask to Exposure.
  4. Import the aligned greyscale demo maskA managed copy is stored with the catalog.
  5. The mask is connected to ExposureThe photo changes only when the connected adjustment has an effect.
  6. Apply an exposure correctionThe mask limits this global tool to the selected area.
  7. Invert swaps selected and protected areasThis changes the actual mask polarity.
  8. Restore the original polarityReview the edge and alignment before exporting.
  9. Opacity controls the mask contributionOverlay display settings are a different thing.
  10. Disconnect returns Exposure to global coverageIt keeps the tool’s numerical adjustment.
  11. Use mask reconnects the available imageOther supported tools can use the same shared mask.
  12. Replacing the shared image affects every connectionReview each connected tool after a replacement.
  13. Back up the catalog’s masks folderPreset JSON stores a file reference, not the mask pixels.

What an external mask does

An external mask uses an image's pixel values to restrict a supported global adjustment. White selects, black protects, grey gives partial coverage and transparent pixels protect. This workflow is separate from a local's editable radial, brush or pen shapes.

Use it when you already have a suitable mask made elsewhere, or need a shared image mask for several compatible adjustments. It does not automatically align an arbitrary image to the subject.

Prepare the mask image

Make the mask match the uncropped, unrotated source photograph. The source's orientation and framing matter: a mask exported from a cropped screenshot may be displaced when used as a source mask. The imported mask follows later lens, rotation and crop changes.

OmaRAW stores a managed greyscale PNG with the catalog, limited to a maximum edge of 4096 pixels. Large masks are reduced to that limit, so inspect fine boundaries. Keep the original mask file too if you may want to rework it at higher resolution.

Import and connect

  1. Open Develop → Masks → External mask.
  2. Select the adjustment to limit, then choose Import and select the aligned image.
  3. Apply a modest change in that adjustment and compare its effect to confirm placement and polarity.
  4. Use Invert if black and white represent the opposite of what you need.
  5. Choose another supported adjustment and Use mask to connect it to the same managed image.

Supported targets include Exposure, Tone equalizer, Colour grading, Contrast & texture, Clarity, Sharpening, Contrast equalizer and RGB primaries. These connections do not create a new local correction panel; you still edit the actual connected global tool.

Opacity reduces the connected mask’s contribution without changing its image file. Check the effect with the actual adjustment enabled; lowering Opacity and disconnecting the mask are different actions.

Shared mask behaviour

Importing a replacement changes the shared image for every connected adjustment. Review all those tools after replacing it. Disconnect restores the selected adjustment's global effect; it does not reset its numerical settings. An unchanged tool with neutral values may show no visible effect even when connected correctly.

Snapshots and presets retain the connections and managed file path. A preset JSON does not embed the mask pixels. Keep the referenced file available when moving an edit or sharing a preset, and back up the catalog's masks folder. Full catalog backups include imported masks; a manual move must retain that folder.

Troubleshooting

The wrong area changes: check source alignment, orientation and Invert. Do not correct a badly aligned mask by cropping the photo blindly.

Nothing changes: confirm the target adjustment is enabled and has a visible correction, and that the mask is connected and contains selected pixels.

Another tool changes after replacing the image: the external mask is shared. Review its other connections.

A moved preset loses its effect: reconnect or restore the referenced managed mask file. The preset carries a reference, not an embedded mask.

Recording scope

The lesson imports a simple greyscale demonstration mask aligned with the sample photo, connects it to Exposure and shows the resulting restricted correction. It illustrates polarity and connection behaviour; it is not presented as an AI segmentation result.