Backdoctor said:

I thought once you blew highlights they were gone. How can you recapture blown or lost highlights?

If you look at RAW data, as it comes from the camera, you will see that there is some information in the areas that seem to be blown out.

Here are couple of reasons why diferent raw converters have different tolerance to blown highlights.

Let's assume in 12-bit RAW file (4095 is the maximum value that can be represented with 12 bits) we have RGB highlight values 4000, 4000, 4000. We need to apply typical white balance for daylight, that is multiply R by 2.8, and B by 1.2 (numbers are for D2h). Now, we need to make gamma correction. Let's say gamma is 2.2 If we normalize by 12 bits, we are getting as a result

((4000/4095)*2.8 )(1/2.2)*255 = 403;

that is - we have overflow. So, normalization and number of bits used for result determine precision of highlight manipulations.

To avoid this, we use different normalization, work in linear gamma, and work in floating point. Slow...