Archived posting to the Leica Users Group, 2014/03/22
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]I'm not convinced on this sampling voodoo! I also want to sit down and counsel you on the errors of your ways regarding pixels per inch and dots per inch...but I think I hear Dr Ted approaching! Just before I get slapped on the back of the head... Gaah! My model booked for this afternoon just cancelled due to illness so I'm back on keyboard. No you mean pixels per inch for the resolution. But resolution is irrelevant until you choose a physical size that you want to print. Up or down sampling matters to make a say 24MP image a 12MP or a 36Mp or whatever. You can make up new data or throw away data but it is independant of resolution. The 360DPI 'standard' for printing comes from circle of confusion theory and theoretical printer native capabilities. Hower ink jet printers do not just make one size, one tonal value. one colour one fixed DPI patterns in any case. They make variable sized, toned and coloured overlapping/variably spaced patterns. Trust me, let LR do the math for you (whether letting it select suitable ppi for you or resampling to fixed value you choose) for your physical print size ;-) Slap! Ouch sorry doctor, I'm outta here! Cheers Geoff http://www.pbase.com/hoppyman On 23 March 2014 09:52, Robert Adler <rgacpa at gmail.com> wrote: > Geoff is correct with pixel dimensions; I must have been looking at a > cropped image. Question still stands though... > > > On Sat, Mar 22, 2014 at 4:45 PM, Bob Adler <rgacpa at gmail.com> wrote: > > > Hmmm. Lemme check again. Could have been a cropped image I used. > > But my question still stands: if I double the pixels to get smothered, > > more realistic details as Howard stated, how do I then downsize the > > dimensions to retain that effect? > > Thanks, > > Bob > > > > Sent from my iPad > > > > > On Mar 22, 2014, at 4:38 PM, Ken Carney <kcarney1 at cox.net> wrote: > > > > > > Bob, > > > > > > There must be a wrong setting somewhere. I don't have a Leica M but I > > imagine the file size is larger than 3352 px. My 5D II files are 5616 > px. > > Jeff Schewe says that upsizing to 200% is usually no problem and that > has > > been my experience with "preserve details" in Photoshop. The 5616 px > files > > are 18.7" at 300 ppi, so I could have some cropping room with modest > > upsizing in PS. Lord only knows what we are talking about with your MF > > gear :) or whatever the emoticon is for envious. > > > > > > Ken > > > > > >> On 3/22/2014 4:59 PM, Bob Adler 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 > > >>> > > >>> _______________________________________________ > > >>> Leica Users Group. > > >>> See http://leica-users.org/mailman/listinfo/lug for more information > > >> _______________________________________________ > > >> Leica Users Group. > > >> See http://leica-users.org/mailman/listinfo/lug for more information > > > > > > > > > > > > _______________________________________________ > > > Leica Users Group. > > > See http://leica-users.org/mailman/listinfo/lug for more information > > > > > > -- > Bob Adler > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information >