On Sun, Nov 7, 2010 at 8:45 AM, Boris Liberman <[email protected]> wrote: > On 11/7/2010 2:58 PM, Tim Øsleby wrote: >> >> I believe that more headroom in the dark areas is in the nature of the >> sensor wells. >> >> When a cup is full, you can't pour more water into it. If you try to, >> you pours over. I think it is almost as simple as that. >> In the dark areas, on the other hand, the information will be obscured >> by noise, but it the information is present. In other words, you can >> recover more information there. >> >> Higher dynamic range gives us opportunity to expose more >> conservatively without loosing information. I think this is what gives >> us more headroom in practical use. >> >> But as suggested; I'm just a bloke who speculates on this topic. >> Others may have mush better answers. > > What you say, Tim, makes perfect sense. But outside of Pentaxia, there are > cameras and sensors that have more headroom in the bright areas. Or at least > so it is said. I'd like to see some measurements in that regard, or better > yet reports of actual experience when exposure had to be corrected in post > so as to recover bright areas... > > Boris >
Practical headroom is determined by dynamic range, but the 'RAW Headroom' that everybody talks about is simply the difference between the maximum value that the default camera conversion curve uses and the actual maximum luminance value in the file. This varies greatly depending on the camera and is inherited from the camera's JPEG rendering engine (as default RAW curves typically try to match the JPEG engine's choices for exposure). -Adam -- PDML Pentax-Discuss Mail List [email protected] http://pdml.net/mailman/listinfo/pdml_pdml.net to UNSUBSCRIBE from the PDML, please visit the link directly above and follow the directions.
