[Leica] Random observations on resolution (long and irrelevant to the craft of being a good photographer)

[hopsternew at gmail.com (Geoff Hopkinson)]

There is something amiss in your settings or calculations or typing there
Bob ;-)
You certainly are not using all of the file's pixels at your starting point
before whatever resampling process you are describing there. Those DNGs
ought to be 3992x5976. 240PPI is the native resolution of course but the
only figure that counts for your purpose there is the number of pixels. I
suggest just setting the output size (physical dimensions) for a print in
LR too and let LR do its smart thing rather than use that fixed 360PPI
figure too. Give it a try if you haven't done so?


Cheers
Geoff
http://www.pbase.com/hoppyman


On 23 March 2014 07:59, Bob Adler <rgacpa at gmail.com> wrote:

> Hi Howard,
> Trying to wrap my layman's brain around this.
> When I bring an M240 file into CC from LR with no resolution change, it is
> 2,682 x 3352 px at 360dpi. It is 7.45 x 9.311 inches in size.
> So if I use bicubic smoother and upsize the number of pixels to 2x(2,682 x
> 3,352) or 5,364 x 6,704 at 360dpi I should get the effects you are
> predicting: sharper looking images with smoother gradients BUT is now a
> 14.9 x 18.622 inch size.
> What needs to be done then if I want my print size to be at the original
> dimensions: 7.45 x 9.311 inches? Or a larger size than the now 14.9 x
> 18.622 inches?
> Thanks,
> Bob
>
> Sent from my iPad
>
> > On Mar 21, 2014, at 7:40 PM, Howard Ritter <hlritter at bex.net> wrote:
> >
> > Poking around with huge degrees of enlargement and up-sampling (but
> perhaps not irrelevantly so for making large prints of landscapes, etc) in
> PS with files from M9, M240, NEX-7,and D800 (not E), I found:
> >
> > 1. The D800's 36MP FF sensor with the current Nikkor 35/1.4 at f/5.6
> produces conspicuously better detail near the limit than the M240's 24MP FF
> sensor with the Summilux 35 ASPH at 5.6 does, and the NEX's 24MP APS-C
> sensor (same pixel size as a 54MP FF sensor) with the kit 18-55 zoom set to
> produce the equivalent of FF 35mm FL produces about the same image
> resolution as the M. This is not the end-all of important sensor
> characteristics, but it can be an important one under some circumstances.
> What this tells me is not only that a 24MP FF sensor does not put modern
> premium prime glass to the test, but also that even inexpensive modern
> kit-zoom glass would not be outclassed by a 54MP FF sensor with regard to
> resolution. This would seem exactly analogous to the role of fine-grain
> film back in the day (anyone remember that stuff?). One wonders what Leica
> AG (and every other manufacturer's) engineers make of this fact, and
> whether there is a 54MP camera (M540?) or beyond in their minds. Of course,
> as with Microfile film, the part of the "need spectrum" such capability
> occupies would be very small. Still, Microfile had its enthusiasts beyond
> microfilming documents for efficient filing. I'd like to know what pixel
> count (disregarding tradeoffs in noise etc) corresponds to the innate
> resolving power of the best modern glass at center and optimum aperture.
> Given the improvement produced by the ~25% linear increase from 24MP to
> 36MP and the 50% increase to (an effective) 54MP, it's clearly at least 1.5
> times, and maybe twice, the linear count of a 24MP sensor (i.e., ~50 to
> 100MP). And what pixel count corresponds to the best general-use emulsions
> from the Age of Film (K64, Plus-X, etc) in terms of lp/mm? Anyone have a
> reference? These results also make me wonder about the actual utility of
> the new superpremium normal lenses, the 50mm Summicron ASPH and Nikon's
> 58mm 1.4, with current sensors. Maybe they extend the envelope in which
> they are not outmatched by the sensor further from the center and from the
> optimal aperture beyond what lesser lenses do.
> >
> > 2. Doubling the linear number of pixels H and W in PS produces a clearly
> smoother image, with what appears to be better resolution, near the limit.
> I know that in theory this is illusory, as creating new pixels from the
> averages of their parent and neighboring pixels cannot add new information.
> But the appearance of doing so is strong, and I think this is a result of
> the fact that for the most part, natural subjects are not wholly random but
> have fractal dimensions and high degrees of internal correlation: for
> example, linear or continuous features are common, such as areas, edges and
> boundaries, and so on. Such features are not likely to be confined to a few
> pixels but to extend over many. Multiplying pixels as is done in PS can
> create a powerful illusion of making a linear feature seem better defined
> and sharper. If you took a picture of a wall of tiny square, randomly
> colored tiles such that the image of 4 tiles in a square exactly occupied
> an entire pixel, the original file would make the 4 look like 1, with a
> color representing their average (this is a thought experiment, ignoring
> the fact that we deal, Foveon aside, with single-color pixels and Bayer
> patterns). Pixel-doubling would then produce not a faithful depiction of
> the actual 4 tiles making up the square, but an illusion of 4 tiles and an
> artificial average color for each of the virtual tiles. But this is a very
> unnatural situation, and in real life, with natural subjects, what appears
> at any given point in an image is likely to closely resemble what appears
> at the points that correspond to the adjacent pixels, so that
> pixel-doubling does, in at least a semi-real sense, have the effect of
> increasing the visual resolution of the image. I think of up-sampling the
> original file to increase the pixel count as "unmasking" information that
> was implicitly there as a result of the innate characteristics of the
> physical world.
> >
> > --howard
> >
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