Russ Butler wrote:
>
> I made the comment about blown pixels in jest though raw therapee and smart
> curve (a plugin) show a few clipped highlights. I surely couldn't "see" that
> from a histogram and certainly not by eye.
>
I just took a look at Smart Curve. As a relatively small time effort by
one person, I'm not sure it should be considered definitive. In fact,
I'm not sure what would be definitive. In the example I just posted,
three well known, widely used and respected apps disagreed about the top
end of the histogram for the same image.
In a "perfect", 8 bit histogram/exposure, the highest tonal values of
each channel could all be 255. So how does one differentiate between a
pixel at 255 that is the true, correct value and a neighbor that should
be 257 to retain correct color? Even if there are no individual
color/pixel values above say 250, it would be possible that clipping had
occurred in some step of capture or processing and overall brightness
simply lowered a few steps in a later edit. I've seen this clearly in
some images on the web, a huge spike somewhat below 255 and nothing
above the spike
When I do RAW conversion, I leave the top end at least a tiny bit below
the top, if possible. ACR has a facility like Smart Curve that shows
any clipped histogram ends, although in two ways, not one.There weren't
any with conversion of this image. As the conversion is 16 bit, that
doesn't really lose any dynamic range. All my editing is done with
consideration for the histogram. For example, after any LCE, I always
check the histogram, and sometimes redo that and the previous step to
avoid clipping. (There are other ways to correct it, but let's keep it
simple.) There are, of course images where I let a little clipping occur
for effect, but I'm always aware of it.
Before down sampling and converting to 8 bit for web display, I adjust
the top of the tonal data to just "kiss" the end of the histogram to
retain the full range of brightness possible in the display image.
> It would take a helluva lot more clipping to degrade that image, which is
> lovely and very rich, especially in aRGB.
>
Again, I'm glad you like it. And thanks for looking and commenting.
Moose
--
_________________________________________________________________
Options: http://lists.thomasclausen.net/mailman/listinfo/olympus
Archives: http://lists.thomasclausen.net/mailman/private/olympus/
Themed Olympus Photo Exhibition: http://www.tope.nl/
|