On 2/4/2025 5:19 PM, Ken Norton wrote:
What MikeG is saying is that it does make a difference, blurring the
corners, in his experience.
That absolutely used to be the case. I've used Lightroom almost exclusively
for the past seven years and have found that this algorithm and the lens
profiles has gotten so good that the corner degradation is largely a thing
of the past. Not totally, but with these latest/greatest (or semi-greatest)
lenses from Sony, the results are excellent. That said, my 28-70 kit lens
totally sucks pond water. Well, it sucked ocean water...
Digital rejiggering of images decreases sharpness. That's just the way it
is. MikeG can do the math; me, not so much.
Ctein contends that Bayer array color loses about as much fine detail as
halving resolution, because of the interpolation.
So, interesting thing about that. I called Ctein out on it and he
acknowledged that it was based on one style of algorithm, but then defended
it by saying "well, the color information still has lower resolution."
It depends on which converter, and which version, and which camera sensor.
So nobody is right, and nobody is wrong.
Converters can use a 3-pixel merge or a 4-pixel merge. There is such a huge
misconception about the 2x green pixels and everybody thinks that it has
something magical to do with the luminance information used by the green
channel and so forth. Actually, the reason for the 2x green pixels is that
when we use the 'nearest neighbors of the "intersection" of the pixels,
there is always one green, one red, one blue pixel to work from. The
lumenance and color is derived from the averaging of those three pixels.
Not four. It's a rare converter that actually uses 2 green. One of the
problems with the Olympus E1 was that it NEEDED a 4-pixel merge in order to
keep from turning the picture into a mosiac. Converters used to treat
luminance separately from color, but they are now mostly done together and
is based on the three-pixel merge for both.
As to the 50% loss of resolution, I would disagree because the empirical
evidence shows that with the application of the appropriate sharpening at
the pixel level, we can achieve per pixel edge definition.
I'm not entirely convinced. Perhaps not 50%, but there is some loss. One difference 'tween you and Ctein is that he is
a printer/empiricist. I've been in his printer room, looking at 100% prints. Some things I believed were confirmed,
others, not so much. Haven't seen him since COVID hit. But we do correspond. Just working on a response to his article
on NR in the latest newsletter. Hint - he may not have found the best, or, of course, there isn't a best for all images
and uses.. 🙂
And yes, I'm a demon sharpener. I have a practical knowledge of what it can and
can't do, for my uses.
The difference
between what Oly's HR mode and a standard merge is doing is that HR mode
does not require the corrective sharpening.
Well, yes, if downsampled to match pixel dimensions, light sharpening to
compensate for sampling loss.
That said, where HR mode really
shines is the increased depth of color and glassiness to the image which is
likely a result of the oversampling that is occuring.
Yup. I did my original comparisons using pix of a Christmas tree, lots of sharp needles and wild color lights. HR did a
MUCH better job on the lights, colors, clipping, haloes. I was the one who turned Ctein, with his obsession with holiday
lights, onto this, way back when Oly HR first came available.
I bring this up because with Lightroom's latest/greatest converter,
especially with the SONY cameras, it is actually performing a multi-pass
process which does the normal convert of the nearest neighbors, but then
does a second convert to calculate the in-between values. This is then
combined to find a better value for the resulting pixel. I haven't figured
out how much it is applying, but it's definitely throwing extra spices into
the pot of chili.
I'm always using ACR/LR conversion. Used to be they were using Oly's own, proprietary conversion algorithms. Sometime
when I wasn't paying attention, that may have changed.
--
What if the Hokey Pokey *IS* what it's all about?
--
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