Archived posting to the Leica Users Group, 2014/03/22

[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]

Subject: [Leica] Random observations on resolution (long and irrelevant to the craft of being a good photographer)
From: kcarney1 at cox.net (Ken Carney)
Date: Sat, 22 Mar 2014 19:05:24 -0500
References: <CA150CA4-2613-43B4-9ACB-A56C38EDA41D@bex.net> <glzK1n00n0AFV7C01lzLmq> <532E1F0C.1040408@cox.net> <gnlS1n0030AFV7C01nlTsh>

I think maybe Howard is suggesting doubling the pixel count at the same 
image size, e.g., an 18" wide print at 720ppi?  As I recall, Jeff Schewe 
suggests changing the resolution from 360 to 720ppi for printing.  I 
tried that but didn't see any benefit.  As far as up-sizing for a larger 
print, my guess is that one would need two files - one 9" print at 360 
and one 18" print at 360.  I think I have just exceed my pay grade.

Ken


On 3/22/2014 6:45 PM, Bob Adler 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
> _______________________________________________
> Leica Users Group.
> See http://leica-users.org/mailman/listinfo/lug for more information




In reply to: Message from hlritter at bex.net (Howard Ritter) ([Leica] Random observations on resolution (long and irrelevant to the craft of being a good photographer))
Message from kcarney1 at cox.net (Ken Carney) ([Leica] Random observations on resolution (long and irrelevant to the craft of being a good photographer))