Merge photos

DarkRay merges RAW frames into one new photo: an HDR from a bracket, a panorama from overlapping frames, or an HDR panorama from several brackets. The result is an EXR file that lands in your catalog beside its frames and opens in Edit like any other photo, with the highlights intact.

Start a merge

1. In the Library grid, select the RAW photos to merge. Only RAW files can be merged.

2. Choose one of the Image menu commands, or right-click the selection:

   Command	Needs	Key by default
   Merge to HDR…	2 or more frames	Ctrl+H
   Merge to Panorama…	2 or more frames	Ctrl+M
   Merge to HDR Panorama…	4 or more frames	none

3. The merge window opens on a reduced-resolution preview. Change any control and the preview updates; only the steps after that control run again.

4. Click Merge. The window closes and the full-resolution merge runs in the background, with its progress and a cancel button in the status bar.

Only one merge runs at a time. A virtual copy and its master count as one frame.

The frames must come from one camera at one size. If they don’t, the preview says, for example, “These photos aren’t all the same size (6048×4024, 4024×6048). An HDR merge needs its frames at one size and orientation.” A panorama accepts a frame turned to portrait among landscape ones.

Find the result

The merge writes a new file and adds it to the catalog:

• Name: <reference frame>-HDR.exr, <first frame>-Pano.exr or <first bracket's reference>-HDR-Pano.exr. If that name is taken, a suffix is added. A merge never replaces a file.
• Place: next to its frames, or in the folder you set in Preferences › Library › Merge.
• Stack: the result sits on top of a stack with its frames, unless you turn off Stack with sources. A frame the stitch left out is not stacked.
• Collections: the result joins every collection its frames are in.
• Edits: it starts with the reference photo’s edits (see below).
• Selection: the grid selects the result when the merge ends.

A merged photo shows a small M badge; hover it for “Merged: an HDR of 3 photos”. Next to the EXR, DarkRay keeps a .merge.json file that records what the merge used. It moves with the photo.

Note

The result starts with the reference photo’s Base layer edits. Lens, denoise and crop settings are reset, because the merge already applied the lens and the frame is new. Local layers are not copied. If the reference had no edits, the result has none.

Output, lens and white balance

Every merge window ends with two sections you can leave alone.

Normalize gives every frame the same treatment before merging:

• Lens profile shows the profile that will be applied, or “No profile: the frames merge uncorrected”. Choose… picks another from the lens database; it unlocks once the first preview has read the frames. If the first frame in the list has lens settings in Edit, the merge uses them for every frame, so set up that frame’s lens first if you need a custom one.
• White balance names the frame whose as-shot white balance every frame uses. It starts on the middle frame.

Output has Save next to sources (off writes to the Preferences folder; it is locked on until you set a folder there), the file name, and Stack with sources.

In Edit, a merged photo shows “Merged file: lens profile and denoise are already applied.” under RAW Process, with only the manual trims left. See Editing for the rest of the controls.

Change the defaults

Preferences › Library › Merge sets where merged files go, the EXR compression (ZIP, PIZ or None; all are lossless), the starting deghost amount, the starting projection, and whether results are stacked. See Library, Import and Edit preferences.

Tip

Merging is slow with large files. Check the preview and the controls first, then click Merge and keep working: the job runs in the background.

Technical details: how frames are prepared

Merging works on the RAW data, in linear light, with no camera response curve to guess. Each frame is decoded without auto brightness, with the same white balance for all frames, so pixel values compare directly. Photosites at or above 98% of the sensor’s white level are marked clipped and never count. Each frame then gets a RawPrep-style bake: lens distortion, vignetting and defringe from its profile, with no denoise.

The result is a half-float EXR in ProPhoto primaries with ZIP compression (or the compression you chose), scaled so it opens looking like the reference photo does in the catalog. Values above 1.0 are kept.

The preview uses a half-size decode, shrunk to a 2048 px long edge. The full-resolution job runs on the CPU and needs a lot of memory: about 9 GB for three 45-megapixel frames and about 11 GB for a large panorama in DarkRay’s own measurements.