How to crop DNG files?

[dreed]

With the latest Bridge and Lightroom, it is possible to create panoramas from camera raw files that come out as DNG files. Due to both the amalgamation of data and the change in file format, the size the resultant DNG files can be quite large - complete with lots of areas that are useless.

The "Autocrop" in Bridge & LR decreases the size of the JPEG previews in the DNG but does not appear to change the raw data at all.

How do I crop and save a DNG file to be smaller (i.e what's visible) than the original DNG "raw" file?

[PeterAit]

I don't understand why this is a problem.

[Schewe]

How do I crop and save a DNG file to be smaller (i.e what's visible) than the original DNG "raw" file?

You don't...crops in ACR/LR are not applied until you render. Up till then the entire file is there because the crop is only a non-destructive edit.

[dreed]

You don't...crops in ACR/LR are not applied until you render. Up till then the entire file is there because the crop is only a non-destructive edit.

Ok. Will PS (or any other tools) do a destructive crop on a DNG file?

[john beardsworth]

You could try exporting the DNG from Lightroom as a Lossy DNG with whatever dimensions you want. Then reimport it and discard the full size DNG. I wouldn't do it (I'd just get more hard drive space) but it might be editable enough for whatever you want to do.

[Peano]

Ok. Will PS (or any other tools) do a destructive crop on a DNG file?

When you open the image in PS from ACR, it is no longer a DNG file. As long as you don't open it as a smart object, you can make a destructive crop in PS. Just make sure the crop tool is set to "Delete cropped pixels." (The original DNG file will remain uncropped, because it is a raw file.)