Doug Kerr
Well-known member
Yesterday (as an indirect result of a link given in another thread in this forum) I acquired a really useful tool, PhotoBola's Raw Image Analyzer (a.k.a Rawnalyze). This is a program that will allow the user to ascertain many things about a raw data file, including a tricolor raw histogram. (Its functionality somewhat overlaps that of the program Iris, but it is perhaps more straightforward to use for many of the matters we might wish to examine.)
A Windows version is available here:
http://www.cryptobola.com/PhotoBola/Rawnalyze.htm
Many fascinating facts have come to my attention in reading the literature on the program and in its extensive Help facility.
One is that there will often be in the proprietary metadata in the raw file (certainly for Canon EOS cameras) a parameter I will describe as a "suggested push/pull factor". This evidently suggests to the raw development package a suggested amount by which the resulting tonal scale should be shifted from that which is "normal", as we do when compensating for over- or underexposure. ("Normal" probably has to be interpreted in terms of the "normal" algorithm used by the camera manufacturer's own raw development software.)
This is in effect a suggested initial setting of the slider on the raw development control panel that is sometimes labeled "brightness", "lightness", or even "exposure".
[I have pointed out here that this last label is not technically apt, an observation that is echoed precisely in the Rawnalyze literature, but its meaning is commonly understood. As one colleague here aptly pointed out, it allows us to make essentially the same change in the developed image that would have resulted from a greater or lesser exposure.]
My metaphorical description here of this as a "push/pull" control is of course based on the colloquial terms used in connection with the film technique of using a non-standard development to change the response curve of the film, again usually to compensate for over- or underexposure.)
Moving along, the next point was that, in modern Canon EOS dSLRs with the "highlight tone priority" feature, when that feature is in effect, the "suggested push/pull factor" in the metadata of the raw file is usually +1.0 stop.
Again, this can give us some further insight into the working of this still-somewhat-mysterious feature.
I expect that all the above is old news to the regular raw-wallopers here, but as you know that is new territory for me.
A Windows version is available here:
http://www.cryptobola.com/PhotoBola/Rawnalyze.htm
Many fascinating facts have come to my attention in reading the literature on the program and in its extensive Help facility.
One is that there will often be in the proprietary metadata in the raw file (certainly for Canon EOS cameras) a parameter I will describe as a "suggested push/pull factor". This evidently suggests to the raw development package a suggested amount by which the resulting tonal scale should be shifted from that which is "normal", as we do when compensating for over- or underexposure. ("Normal" probably has to be interpreted in terms of the "normal" algorithm used by the camera manufacturer's own raw development software.)
This is in effect a suggested initial setting of the slider on the raw development control panel that is sometimes labeled "brightness", "lightness", or even "exposure".
[I have pointed out here that this last label is not technically apt, an observation that is echoed precisely in the Rawnalyze literature, but its meaning is commonly understood. As one colleague here aptly pointed out, it allows us to make essentially the same change in the developed image that would have resulted from a greater or lesser exposure.]
My metaphorical description here of this as a "push/pull" control is of course based on the colloquial terms used in connection with the film technique of using a non-standard development to change the response curve of the film, again usually to compensate for over- or underexposure.)
Moving along, the next point was that, in modern Canon EOS dSLRs with the "highlight tone priority" feature, when that feature is in effect, the "suggested push/pull factor" in the metadata of the raw file is usually +1.0 stop.
Again, this can give us some further insight into the working of this still-somewhat-mysterious feature.
I expect that all the above is old news to the regular raw-wallopers here, but as you know that is new territory for me.
Haven't heard of this one