How to recover seemingly lost highlight detail without adding unsightly color casts, or how to get digital blown-out highlights to look like the film ones...

It's actually quite simple. You will only need the gimp and the gimp-ufraw plugin.

Just open the raw image in gimp with the ufraw plugin.

First, make sure that highlight clipping is off, and tick on the overexposure indicator. Then decrease the exposure slider until all the overexposed areas (blacked out in the picture) are gone. The gimp-ufraw plugin dialog should look like that:

Ufraw, keeping all the highlight information

Then, let ufraw process the image and open it in gimp.

Now, open the file again and let the gimp plugin open ufraw. Keep all the settings exactly the same as they previously were, except for the highlight clipping tick box. This time, make sure it is on. The ufraw dialog should look like the following:

Ufraw, with the highlight clipped

You can now let ufraw process the image. You will end up with a second copy of the image in gimp. Choose the unclipped one - the first one we generated - and create a new empty layer. Copy the clipped image - the other one - and paste it in this new empty layer. Finally choose Saturation mode for the top layer. You should end up with something like this:

Layers and Saturation merging mode in gimp

The highlights should now be desaturated by the masking first layer and the colour cast should be gone. Finally if you are happy with what you see, merge down the two layers and save your image.

Here is an example:

Unclipped with the wrong sky color
The first image: all the highlight details are there but the coulours are off. - The sky for example is pinkish. -

Clipped with loss of highlight detail
The second image: the previous color cast is gone in the washed out highlights. However, the transition zone shows a rather greenish tint, and a lot of detail has been lost. The clouds are now barely visible.

Final image with correct colors and highlight details
The final result: the highlights conserve all the details without showing any strong color cast.

Here is a second example:

Kazimiers Dolny, wrong highlight colors
This one shows all the detail information, but the blown-out highlights are pink instead of white.

Kazimierz Dolny, clipped image
This second image lacks some of the detail in the highlights - in the branches for instance - and gets some rather weird yellow color in the transitional highlight zone - 1 or 2 out of 3 channels blown-out -

Kazimierz Dolny, final image
The final image: the highlight detail is there and the fake yellow color is gone.