Handing your cull to Lightroom in a sidecar

Checked against CullTone on 18 Oct 2026.

An XMP sidecar is a small text file that sits next to a RAW with the same name, DSC01234.xmp beside DSC01234.ARW, and carries what the RAW doesn't: stars, colour labels, a caption, develop settings. Lightroom Classic and Camera Raw read it, which makes it the plainest way to carry a cull from one program to another.

It's plain text, so open one in any text editor once. Most hand-off problems turn out to be a field that isn't where the other program looks.

What a CullTone sidecar says

The reason goes into the caption, so "one of 6 near-identical frames; frame 0412 is kept instead (eyes closed)" travels with the photo and you can read it in the Library module.

Then the edit: exposure, white balance, contrast, highlights and shadows, curves, the colour bands, colour grading, vignette, grain and crop, in Lightroom's own slider names. If you adjusted a photo in CullTone, the sidecar carries your adjustment; otherwise it carries CullTone's starting edit. If you only want the cull, CullTone can also write sidecars with the stars, label and caption and nothing else.

Keep is 4 stars, not 5. Plenty of photographers save 5 stars for portfolio picks, and a cull handing out 5 stars by the hundred would take that away from you.

To check one by hand, look near the top for xmp:Rating="4", xmp:Label="Green" and the caption inside dc:description. If those three are right, the cull will reach Lightroom.

Getting Lightroom Classic to read them

1. Put each sidecar in the same folder as its RAW, with the same base name. Lightroom ignores a sidecar anywhere else.
2. If the photos aren't in your catalog yet, import them. Lightroom reads the sidecars on import.
3. If they're already in the catalog, select them and choose Metadata, then Read Metadata from Files. This replaces what the catalog holds for those photos, including any Lightroom edits since. Do it before you start editing in Lightroom, never after.
4. Filter by the green label or by 4 stars, and there are your keepers.

Colour labels are where it usually goes wrong. A sidecar stores the label as a word, and Lightroom matches that word against the names in your current label set. The default set uses plain colour names, so "Green" lands as green. If you renamed yours ("Client pick" for green, say), "Green" no longer matches and those photos arrive with a white label. Switch to the default label set while you import, or filter by stars.

Then the awkward step. CullTone Desktop saves its sidecars in its own folder on your Mac, not beside your RAWs, and there's no button yet that copies them across. For now that copy is by hand, and it's the weakest part of this hand-off.

Why the edit won't match to the pixel

It lands in the right direction and at roughly the right amount. Not identical, and that's structural.

CullTone starts from the camera's own colour, the look the camera itself would have given the JPEG. Lightroom starts from its own profile, Camera Standard or Adobe Standard, so the two disagree before a single slider moves. Their slider scales differ as well, so every number in the sidecar is a translation, and white balance in particular is an estimate that can wander under odd light, like a reception lit in magenta uplighting.

JPEG originals land closer, because both programs start from the same pixels.

Every sidecar CullTone writes passes exiftool -validate, which checks the file is well formed, but we haven't yet imported a set into Lightroom Classic and compared it frame by frame with CullTone's own JPEGs, and the crop angle and the white balance are the parts we're least sure of. Until we have, trust the sidecars for the cull and treat the develop settings as a starting point. If CullTone's JPEG is the look you want, deliver that and skip the round trip.

If you try the comparison before we do, we'd love to see it. The Lightroom hand-off page will carry the result once we have one.