How can I reverse-engineer the RAW conversion settings used in a JPEG image?

Question

I've lost my Lightroom catalog during OS migration. I have couple of JPEGs developed from RAWs and would like to put few more JPEGs from other RAWs in similar mood. Is there a way to reverse engineer development settings having RAWs and JPEGs developed from them?

Answer 1

There's no magical approach here. You'll have to look at each one. However, you have an advantage since you did the work yourself: you can, hopefully, look and be reminded of what you did.

Other than that, the only way is to be familiar with the camera, software, and RAW development in general, and then apply that expertise to each image.

Answer 2

I have noticed that in the combination of CameraRAW (via Bridge) and Photoshop some (!!) settings are written as metadata to the JPEG - at least that is what some of my Flickr images imply.

However there is a huge but with this: It is only a few settings - and some values are missing completely, e.g. noise reduction.

Answer 3

If all else fails do it the hard way.

I assume you have only done raw conversions and nothing more. If you look at it from a theoretical point of view then you have a high dimensional input (raw file), a high dimensional output (jpg) and you need the function that maps input to output. You are lucky because you have the function but need some parameters.

The dcraw and ufraw are two raw converters that can be used from the command line, I don't think that Lightroom let's you do this.

What you would need:

• A distance function between two jpeg images. The sum of |pixel-differences| might work.
• A search function. A Genetic Algorithm would be easy but probably not the best solution. Directed search is better. Maybe a greedy algorithm?

Anyway, this could be done with a bit of time and a quick computer.