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#571
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why wet prints > 300 dpi MF costs more cuz its much better
Bill Hilton wrote:
From: (Bob Monaghan) Do the math on a 300 dpi vs. Leica standard print (which is 392 dpi), viz: "300 dpi" is not the right number. 300 ppi (pixels per inch) is a common digital input file resolution but that gets rasterized by the printer software If the input is 300DPI then how could the output being anything else? GIGO? No? Nick |
#572
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is film < 42 lpmm? MF costs more cuz its much better ;-)
"Bob Monaghan" wrote in message ... SNIP basically, one interpretation is that you have to sample at least twice the rate of the maximum frequency you want to characterize. For us, it means that a fixed sensor with say 100 pixels per mm can only respond at a 50 lpmm or lower rate. Correct, it's basic sampling theory (and it's not just a theory ;-) it's confirmed in practice by the observed behavior of all sampling systems). However, it is possible to confuse aliasing (caused by sampling higher spatial frequencies than the Nyquist limit) with detail. Sometimes it isn't too damaging and may mimick (pseudo-) detail. But when film is involved it will result in more prominent graininess that there acually is. And if the noise floor is raised the, inherently low contrast, finest detail will drown in the noise. So when a sensor that has say 124 pixels per mm is in a DSLR, it can respond to 124/2 or 62 lpmm. Theoretical maximum on sensor, yes. Also don't overlook that larger sensors (in terms of mega pixels AND physical size) need less magnification, so they keep their sensor resolution better when output. Sampling pitch, and magnification to output, determine the absolute visible limitations for resolution if all other factors were optimal, which they aren't. Claims that it is recording 75 lpmm or any higher value have to be challenged on the basis of the Nyquist theorem - you aren't sampling fast enough to "see" a 75 lpmm image. Correct. Aliasing maybe, actual detail no. Even the maximum 62 lpmm would be hard to support, because the effects of other system elements like the anti-aliasing low-pass filter and optics and so on would likely reduce the system response below that of the sensor alone. Yes, although since these low-pass filters are not perfect 'brick-wall' filters they mostly attenuate the modulation near the Nyquist frequency. The interaction between lens and sensor (film or CCD/CMOS device), and in some cases also a scanner's lens and sensor, will reduce especially fine detail modulation. But then there is sharpening to compensate for the reduced contrast at higher spatial frequencies. Bart |
#573
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is film < 42 lpmm? MF costs more cuz its much better ;-)
Recently, Bart van der Wolf posted:
(Excellent expansions on BobM's explanation) "Bob Monaghan" wrote in message Even the maximum 62 lpmm would be hard to support, because the effects of other system elements like the anti-aliasing low-pass filter and optics and so on would likely reduce the system response below that of the sensor alone. Yes, although since these low-pass filters are not perfect 'brick-wall' filters they mostly attenuate the modulation near the Nyquist frequency. The interaction between lens and sensor (film or CCD/CMOS device), and in some cases also a scanner's lens and sensor, will reduce especially fine detail modulation. But then there is sharpening to compensate for the reduced contrast at higher spatial frequencies. The difficulty, at least for me, is that sharpening is an artifact in itself. If you look at it at high magnification, sharpening "flattens" the the values of pixels near higher contrast edges. The more sharpening, the wider the band of flattened pixels. So, sharpening along with the generally lower range of color gradations has an impact on the textures in an image. This works for some images, but damages others. Neil |
#575
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missing MF converts Not just feared future fate, but present hurt.
Recently, one_of_many posted:
In article . net, "Neil Gould" wrote: Recently, Q.G. de Bakker posted: [...] I was *not* suggesting that a Leica/Fuji collaboration would be for a film camera. I tried to express that Fuji's large presence in the world of film photographers would make it easier to market *any* photographic product that the partnership made. Certainly, it would be an easier sell than products from the Leica/Panasonic collaboration, because Panasonic does not have as much of a reputation among film photographers. Is this not a moot point because Leica is working with Kodak and Imacon for their new R8,9 digital back? No, it's not moot. I think that there will be a *range* of products available, with the digital back for the R9 falling at the top of their price range. What might kill it (and may be adding to the time to bring this product to market) is that the advantage of "digital specific" lenses may outperform the R9/digital combo. So, it could well be that a $1,500 Lumix dZLR (tm) with a Leica digital lens could produce better images than, say an R9/digital back/100 mm APO that someone paid $10k to have. Even using special lenses on the sensors to better capture the angular rays at the edges of the frame is a compromise, because film lenses vary with regard to those angles. Film is not as sensitive to those angular rays in part due to its 3D nature compared to the "cell wells" of digital sensors. So, while I'm curious about the upcoming R9 back, I'm equally skeptical about its performance. Neil |
#576
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why wet prints > 300 dpi MF costs more cuz its much better
"one_of_many" wrote in message news In article , dy (Bill Hilton) wrote: SNIP "300 dpi" is not the right number. 300 ppi (pixels per inch) is a common digital input file resolution but that gets rasterized by the printer software to a much finer pitch, typical numbers are 720x720 up to 2,880 x 1,440 dpi (dpi is correct here, ppi is correct on the input side). While you don't actually get 2,880 dots/inch of resolution due to ink spreading on the paper you do get a lot more than 300 dpi. Correct, the ppi is the number of smallest picture elements that translate to spatial frequency information in the output, the printer driver *dithers* that in order to approximate continuous tone color resolution. SNIP What difference does a few steps of the step or ink engine make when the ink can't be resolved on the paper. Most of the ink shouldn't be resolved on paper, because we try and mix/blend/dither into 'continuous' tones not directly offered by the inkset. We DO want that dithering to be finer than the visual resolution at the given viewing distance. Just for the hell of it, would a bunch of you all print a calibrated high-rez military target? Simplify it and make it monochrome (B&W). Let's see what printers can really do. My HP printer can resolve(!) detail between 9.5 and 12.7 cycles/mm on glossy paper. Cycles are more relevant than B&W lines, unless you are into line drawings. It can be rather easily tested with a target like: http://www.xs4all.nl/~bvdwolf/main/d...0mm_600ppi.png (2.1MB) http://www.xs4all.nl/~bvdwolf/main/d...0mm_720ppi.png (2.8MB) Depending on the software used, you may need to convert to RGB before printing in color. I also have targets available for camera lens+film (+scanner) testing, they are a bit less demanding on the printer. I've posted their links before, but if requested I'll post them again with instructions. Just print at the indicated ppi(!), measure the central blur diameter and calculate: 120/pi/mm=cycles/mm, where pi is the number 3.14159265..., and mm is the blur diameter in millimetres. If the diameter is more of an ellipse than a circle, then the horizontal/vertical resolution is not the same in both directions (e.g. paper transportation inaccuracy). If you are into line drawings / text, a target like described he http://www.ddisoftware.com/qimage/quality/ will also help to determine the limits, but B&W lines use a lot more ink, and thus bleed easier. Bart |
#577
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why wet prints > 300 dpi MF costs more cuz its much better
"Bart van der Wolf" wrote in message ... SNIP My HP printer can resolve(!) detail between 9.5 and 12.7 cycles/mm on glossy paper. P.S. for the mathematically challenged ;-): that is between 483 and 645 ppi, so printing at 600/720ppi on an inkjet printer does provide more detail than many people think, despite the dithering at 2400/4880 dpi(!). Bart |
#578
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why wet prints > 300 dpi MF costs more cuz its much better
"Neil Gould" wrote in message ink.net... SNIP ROTFL Excellent commentary! And, an excellent suggestion to those that think their inkjets are high resolution printers. Sorry to disappoint you, they are (see my other post in this thread), and you can test it yourself... Now, if you were to address dithered highlight uniformity instead of resolution, than we have a different subject, but on resolution you should really try it. Bart |
#579
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why wet prints > 300 dpi MF costs more cuz its much better
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#580
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is film < 42 lpmm? MF costs more cuz its much better ;-)
"Neil Gould" wrote in message ink.net... SNIP The difficulty, at least for me, is that sharpening is an artifact in itself. It can be, but it should only attempt to restore contrast losses in the imaging chain (most prominent in fine detail). The imaging chain also includes losses in the output medium. If you look at it at high magnification, sharpening "flattens" the the values of pixels near higher contrast edges. The more sharpening, the wider the band of flattened pixels. So, sharpening along with the generally lower range of color gradations has an impact on the textures in an image. This works for some images, but damages others. It may, but sharpening is also a bit of an art, and its success does depend on the image data you start with. I see a lot of poor sharpening examples on the web, I just hope most professionals do better than that. For those using Photoshop, there is an easy method to reduce visual haloing and totally avoid clipping due to sharpening. It requires USM sharpening of a duplicate layer (preferably with an edge mask and prior noise reduction) and blending adjustments such as in this example: http://www.xs4all.nl/~bvdwolf/main/downloads/Non-clipped-sharpening.png. Those can be used as a starting point (for digicam files use a very small radius, large amount, for scans the radius depends on the resolution) and the effect can be tuned for various output media by varying the layer's opacity (exaggerate the sharpening amount and reduce opacity to your liking). Bart |
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