Technie question(s)...

Interesting discussion, indeed. If, for argument's sake, having HTP on changes the RAW file, it's NO LONGER RAW!!!! It's processed RAW! I think I made a new phrase here, and now it's copyrighted...

No, the CMOS chip cannot "up" or "down" the ISO for anything other than the full chip, so it cannot individually change pixel sensitivity where the subject is extra bright. It has GOT to be post-capture processing of the RAW data. I'm just surprised that it would change the RAW data (that explains the menu option rather than just turning it on always - you must select and acknowledge that you will not be getting a RAW image anymore).

tonylong wrote in post #4258264
OK, if it's good for RAW, that would imply tweaking something in the capture process, rather in the software -- I would imagine since it only works above ISO 100 it would involve a "smart" reduction of the amplification applied to the sites (to "up" the ISO from the base (100)) that were judged overexposed...?

I don't know how else it could work with RAW.

RVsForFun wrote in post #4258305
Interesting discussion, indeed. If, for argument's sake, having HTP on changes the RAW file, it's NO LONGER RAW!!!! It's processed RAW! I think I made a new phrase here, and now it's copyrighted...

No, the CMOS chip cannot "up" or "down" the ISO for anything other than the full chip, so it cannot individually change pixel sensitivity where the subject is extra bright. It has GOT to be post-capture processing of the RAW data. I'm just surprised that it would change the RAW data (that explains the menu option rather than just turning it on always - you must select and acknowledge that you will not be getting a RAW image anymore).

OK, I just read an article on this site which explained that HTP is like a toning curve applied by the 14-bit A/D converter (if you check out the lower half of the page you'll see an exposure/dynamic range discussion that includes info on HTP). So, the idea is kind of like I was suggesting, that instead of applying linear ISO amplifying it applies a curved amplification that flattens at the highlights. So, it's not making RAW "less RAW" as much as making ISO amplification less linear. So, that makes sense and could really be an improvement. They did note, however, that 1) HTP seems to generate a little more shadow noise and 2) RAW files still showed a gain in dynamic range over in-camera jpegs.