Archived posting to the Leica Users Group, 2004/02/22
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]On Feb 22, 2004, at 8:19 PM, Henning Wulff wrote: > At 12:37 PM -0500 2/22/04, Jonathan Borden wrote: >> >> I agree the appearance of film grain is a matter of opinion. >> Nonetheless 1) people have gone to the trouble to write photoshop >> filters that *add* grain to digital images 2) gaussian noise is much >> more pleasing than pixelated noise at any given level of noise. > > The gaussian blur filter existed in Photoshop from a very early time, > when it was intended to simulate photographs in drawings done on a > computer, and other image softening effects. The digital photo market > was a _very_ minor factor at that time, but scanned photos were > becoming a significant factor, and gaussian blur was useful when > compositing and drawing to blend photos which had grain and blur. I am referring to the gaussian *noise* function, not the blur function which share only the use of a gaussian distribution, blur for sampling and noise for distributing. > >>> There are certainly no visible "rectangular grains" in any of my >>> pictures, but I have never owned a camera with fewer than 2.2 >>> megapixels. This camera made reasonable 10x8 prints, considering it >>> is a P&S camera. > >> That roughly corresponds to a printing resolution of 75 dpi. You >> might find that acceptable. I am saying that many people would print >> an 8x10 at 300 dpi which is four times that resolution. > > I think your math is a bit adrift. If 8x10 corresponds to 7.2 > megapixels at 300 dpi, then 2.2 megapixels will result in an 8x10 at > 166 dpi. This makes a huge difference from 75 dpi, although I agree > that the quality is noticeably poorer. You are correct. My mistake. > > >>> The earliest digital cameras did produce a mosaic effect and were >>> unusable for normal photography. >>> I have never heard 360 ppi quoted as a maximum resolution, >> >> The Imageprint RIP uses this as a maximal resolution (at least the >> lite version). I personally can't see any significant increase in >> print resolution (with my naked eye) beyond this. You can certainly >> print at a higher resolution -- I am only suggesting that this may >> not result in a better print. >> >> I *am* saying, however, that most people can see a difference between >> 75 dpi and 300 dpi (8 megapixel for 8x10) or 360 dpi (10 megapixel >> for 8x10). The point of this is that we can make some calculations (if done correctly :-) which tell us how many pixels are needed for various quality images at various sizes. Now there is nothing to say that printing at 150 dpi will be horrible, indeed certain images and certain sizes of print (i.e. larger) may do fine with this resolution. Perhaps I am nitpicking about the benefits for higher pixel resolutions but I am amused that folks on this list who wouldn't be caught dead using an autofocus EOS a couple of years ago seem to be flocking to DSLRs. If we want the ultimate in image quality -- and are willing to pay $$$ for Leica glass, then relatively high pixel densities are needed to properly bring this out. Certainly *current* digital images are great for a variety of uses, but just the same current Canon and Nikon glass is great for a variety of uses. This film vs. digital argument is perhaps directly analogous to a Canon vs. Leica argument of years ago: indeed over the web we are hard pressed to tell any differences among a wide variety of modern lenses having a wide variety of costs. Indeed the quality of digital P&S is quite good -- actually the quality of film P&S is quite good assuming one sticks to small enlargements. The one place where I see digital hands down beating out chemical techniques is in color printing. Although it greatly pained me to see Ilfochrome go, it was time. Jonathan - -- To unsubscribe, see http://mejac.palo-alto.ca.us/leica-users/unsub.html