Epson printers - 2400 vs. 4800 ??
in [Digital Cameras]
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From: Nicholas O. Lindan on 6 Jan 2006 15:46 Mark? wrote: > I still challenge anyone to produce evidence that ANY media will show the > useful exhibition of 9600dpi from an ink jet type printer. Don't confuse dpi [random tiny dots] and pixels [resolved information]. 300 pix/inch is what most printers actually provide. Try printing a test target and look with a loupe. For all practical purposes 300 pixels/inch is really all that is needed. 9600 dpi at 300 pix/inch gives 1024 dots/pixel [the number of dots in a square pixel is the square of the number of dots along each side]. If we print only magenta dots then there can 1024 shades of magenta. 256 shades, the minimum for colors to look smoothly gradated, requires 8 dots/pix-inch resulting in a true 1200 pixels/inch. With a 1200 dpi printer at 300 pix/inch there are 16 dots/pixel and only 16 shades of a pure primary color are possible. To overcome this limitation the printer blends adjacent pixels to make intermediate shades and the printer is really doing ~75 pix/inch to get saturated colors. The printers also mix dot colors [pure magenta at 50% will have yellow and cyan dots in it] to make more shades of a color but the color is now unsaturated. As a result, until high dpi printers became available one had a choice of snappy colors at a low resolution or sharp pictures but blah colors. This is also why black & white is so hard to do will with an ink-jet printer with low dpi: 16 shades of grey just doesn't make it. Color is added to vary the apparent density but then the grays change their tint when viewed by a different light and the eye is not well fooled by the color dithering -- yellow + cyan + magenta = dark muddy brown. As a further complication, an inkjet printer builds linear reflectance: 25% dots => 25% reflectance, 50% dots => 50% reflectance. The eye, however perceives logarithmically ["God invented logarithms, man invented the integers." - somebody famous] and the shades are not equally spaced. If black is 2.0 OD: printer #black dots/pix OD 9600 dpi/300 pix/inch printer 1024 2.00 1023 1.96 1 0.00042 0 0.00 1200 dpi/300 pix/inch printer 16 2.00 15 1.14 14 0.87 1 0.03 0 0.00 As is easy to see, there is no possibility for shadow detail in a 1200 dpi printer. If you use 8 bit software, though, you are often limited to 256 shades. # black dots/pix OD Zone Shades/Zone change 255 2.0 0 254 1.86 I 1 251 1.59 II 3 245 1.31 III 6 - detailed black 232 1.00 IV 13 - dark grey 1 0.0017 0 0.00 Easy to see why so many digital photos have no shadow detail. -- Nicholas O. Lindan, Cleveland, Ohio Consulting Engineer: Electronics; Informatics; Photonics. To reply, remove spaces: n o lindan at ix . netcom . com Fstop timer - http://www.nolindan.com/da/fstop/index.htm
From: measekite on 6 Jan 2006 17:07 Nicholas O. Lindan wrote: >Mark? wrote: > > >>I still challenge anyone to produce evidence that ANY media will show the >>useful exhibition of 9600dpi from an ink jet type printer. >> >> > >Don't confuse dpi [random tiny dots] and pixels [resolved information]. > >300 pix/inch is what most printers actually provide. Try printing a >test target and look with a loupe. For all practical purposes >300 pixels/inch is really all that is needed. > >9600 dpi at 300 pix/inch gives 1024 dots/pixel [the number of dots >in a square pixel is the square of the number of dots along each side]. >If we print only magenta dots then there can 1024 shades of magenta. >256 shades, the minimum for colors to look smoothly gradated, requires >8 dots/pix-inch resulting in a true 1200 pixels/inch. > >With a 1200 dpi printer at 300 pix/inch there are 16 dots/pixel >and only 16 shades of a pure primary color are possible. To overcome >this limitation the printer blends adjacent pixels to make intermediate >shades and the printer is really doing ~75 pix/inch to get saturated >colors. The printers also mix dot colors [pure magenta at 50% will have >yellow and cyan dots in it] to make more shades of a color >but the color is now unsaturated. > >As a result, until high dpi printers became available one had a choice >of snappy colors at a low resolution or sharp pictures but blah colors. > >This is also why black & white is so hard to do will with an ink-jet >printer with low dpi: 16 shades of grey just doesn't make it. Color >is added to vary the apparent density but then the grays change their >tint when viewed by a different light and the eye is not well fooled >by the color dithering -- yellow + cyan + magenta = dark muddy brown. > >As a further complication, an inkjet printer builds linear reflectance: >25% dots => 25% reflectance, 50% dots => 50% reflectance. The eye, >however perceives logarithmically ["God invented logarithms, man >invented the integers." - somebody famous] and the shades are not >equally spaced. If black is 2.0 OD: > > printer #black dots/pix OD > 9600 dpi/300 pix/inch printer 1024 2.00 > 1023 1.96 > 1 0.00042 > 0 0.00 > > 1200 dpi/300 pix/inch printer 16 2.00 > 15 1.14 > 14 0.87 > 1 0.03 > > You are one one thousandth off > 0 0.00 > >As is easy to see, there is no possibility for shadow detail in a 1200 dpi >printer. > >If you use 8 bit software, though, you are often limited to 256 shades. > > # black dots/pix OD Zone Shades/Zone change > 255 2.0 0 > 254 1.86 I 1 > 251 1.59 II 3 > 245 1.31 III 6 - detailed black > 232 1.00 IV 13 - dark grey > 1 0.0017 > 0 0.00 > >Easy to see why so many digital photos have no shadow detail. > >-- >Nicholas O. Lindan, Cleveland, Ohio >Consulting Engineer: Electronics; Informatics; Photonics. >To reply, remove spaces: n o lindan at ix . netcom . com >Fstop timer - http://www.nolindan.com/da/fstop/index.htm > > >
From: rafe b on 6 Jan 2006 19:15 On Fri, 06 Jan 2006 20:46:27 GMT, "Nicholas O. Lindan" <see(a)sig.com> wrote: >Easy to see why so many digital photos have no shadow detail. As dot-placement resolutions go up, I would think the "effective contone bit-depth per unit area" would follow, in proportion to dots/unit area. Hey, I like that term... "effective contone bit-depth per unit area." Has a ring to it. Halftoning and error diffusion are not trivial topics. Lots of PhDs working on that stuff nowadays. There are a couple of firmware engineers at my workplace dedicated to just that. Plus there are some nice contone digital imaging systems available to all, eg. LED or laser imaging on photo paper and thermal (dye-sub.) The latter is already used in household printers, albeit usually for very small prints. rafe b www.terrapinphoto.com
From: Mark? on 6 Jan 2006 21:08 Kennedy McEwen wrote: > In article <n5mvf.7911$V.719(a)fed1read04>, Mark? > <mjmorgan(a)cox.?.net.invalid> writes >> Kennedy McEwen wrote: >>> In article <w9bvf.7874$V.6727(a)fed1read04>, Mark? >>> <mjmorgan(a)cox.?.net.invalid> writes >>>> >>>> I contend that there isn't ANY media capable of showing a benefit >>>> of dpi that high. >>> >>> There are plenty of such media, they just aren't papers. :-) >> >> Who said anything about papers? >> I still challenge anyone to produce evidence that ANY media will >> show the useful exhibition of 9600dpi from an ink jet type printer. >> > You didn't say anything about injet printers either! ;-) What is the Canon in question if not an ink-jet type printer (a poorly selected generic term for ink-based printers, since "ink-jet" tends to refer only to HP printers...).
From: David Nebenzahl on 6 Jan 2006 21:16
Mark? spake thus: > Kennedy McEwen wrote: > >> In article <n5mvf.7911$V.719(a)fed1read04>, Mark? >> <mjmorgan(a)cox.?.net.invalid> writes >> >>> Kennedy McEwen wrote: >>> >>>> In article <w9bvf.7874$V.6727(a)fed1read04>, Mark? >>>> <mjmorgan(a)cox.?.net.invalid> writes >>>> >>>>> I contend that there isn't ANY media capable of showing a >>>>> benefit of dpi that high. >>>> >>>> There are plenty of such media, they just aren't papers. :-) >>> >>> Who said anything about papers? I still challenge anyone to >>> produce evidence that ANY media will show the useful exhibition >>> of 9600dpi from an ink jet type printer. >> >> You didn't say anything about injet printers either! ;-) > > What is the Canon in question if not an ink-jet type printer (a > poorly selected generic term for ink-based printers, since "ink-jet" > tends to refer only to HP printers...). They're all inkjets, even those (like Canon) called "bubble jets" or some such other. Inkjet is a generic term for printers what squirt ink onto paper (or other substrate), regardless of what the marketroid types say. (Including "gicl?e", the ultimate $2 snob-appeal term.) Even includes some non-consumer types that use solvent-based (as opposed to water-based) inks. Not poorly-selected at all; describes how they work admirably. -- The only reason corrupt Republicans rule the roost in Washington is because the corrupt Democrats can't muster any viable opposition. |