If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
|
Thread Tools | Display Modes |
#11
|
|||
|
|||
Can't believe someone would say this with a straight face
Eric Stevens wrote:
On Tue, 4 Sep 2012 15:10:18 +0200, Wolfgang Weisselberg Eric Stevens wrote: On Thu, 30 Aug 2012 23:32:18 +0200, Wolfgang Weisselberg Alan Browne wrote: On 2012.08.26 16:19 , R. Mark Clayton wrote: The dot pitch of my printer is 1440 and the "standard" resolution is 360 dpi. At any normal viewing distance this is imperceptible. Not when it dithers over blocks of 64 or more. What do you mean? If I print at 360 on the Epson 3800 (head is 1440) the dithering for a print dot should be no more than 4x4 (16 dithered dots). [not counting dot 'edge' to dot 'edge' dithering]. Why would it dither to 64 blocks? So how many colour steps and gray steps do you get at 16 dithered dots? I understand where you are coming from but the evidence is that the Epson 3800 printer (at least) is not confined to the regular deposition of drops in simple rectangular cells. See http://gerryeskinstudio.com/ABW_sept.../image002-.jpg Not only is it hard (?) to see any visible evidence a rectangular cell containing dot patterns, but it is evident that there need be no simple pattern of dot depositions. All I see is that the head passes over the paper several times[1], with different start timings (which explains the horizontal overlaps) and I guess the head is slightly tilted (so e.g the magenta rows are slightly shifted compared to the other rows). The diagnostic test procedure doesn't suggest the head is tilted. It's more likely to be a subtle difference in timing of the droplet spray. Horizontal, yes, vertical, no. That's either tilt or not perfect alignment of the nozzles. However, the mismatch may be tiny (less than 1/2 diameter of an ink drop), and I guess you'll not see that in the diagnostic test procedure. with the result that overprinting causes colour-mixing and the formation of colours other than those of the raw ink. And then there is the ability of the printer to deposit drops of different sizes, although there is little evidence of this in the particular example. I don't know what the dithering algorithm is that is used by Epson but I suggest it renders moot any analysis based on simple dot patterns deposited in rectangular blocks or cells. Still, printer manufacturers give out dpi ... Buyers expect them, just as they expect megapixels in cameras. So you invent some number? 'dpi' do make some sense. The 3800 has a basic pitch of 360/dpi 360 divided by dots per inch? What's that? which can also manifest itself as 720/dpi. They also claim 1440/dpi and 2880/dpi. Some of the more recent Epson printers built around the same mechanical print engine even claim 5760/dpi. The print engine can move the paper in small increments so that you get 5760 horizontal dot 'lines' per inch (with the specific printer head). The print head can't print as dense, so the horizontal dpi value is smaller, 1440 dpi (or 1440 vertical dot lines). Presumably these subdivisions of the basic pitch are managed by software and timing in some way. Everything's managed by software these days. Once software comes into it there is no reason why dots should be deposited in positions which are simple integer fractions of the basic pitch. The limits of hardware also come into it. Let's make a simple model: Any spot on the paper can take only a given amount of ink before it starts smearing and running. Any dot from the printer has a minimum size and minimum amount of ink. Thus: there's only so many dots that can be printed in any given area on paper before there's too much ink. That gives us a good idea of dpi. There is nothing in the example I cited above which suggests that the ink/paper is anywhere near saturation. The print-pattern is predominantly white space. Irrelevant. It's a 5% gray swatch, so of course you don't get saturation YET. But what you *could* get as saturation and what you could get as an MTF depends on the dpi. [1] The ink nozzle firing repeat rate is too low to place dot on dot in a single pass. Agreed, but we are talking about the print pattern, and the number of colours it can generate. I don't think we are really much concerned about how the print pattern is generated. To understand the print pattern, we need to understand how it's generated, otherwise we'll get a "analog film has infinite resolution as it doesn't have a rectangular pixel pattern" argument. -Wolfgang |
#12
|
|||
|
|||
Can't believe someone would say this with a straight face
On Wed, 5 Sep 2012 22:25:36 +0200, Wolfgang Weisselberg
wrote: Eric Stevens wrote: On Tue, 4 Sep 2012 15:10:18 +0200, Wolfgang Weisselberg Eric Stevens wrote: On Thu, 30 Aug 2012 23:32:18 +0200, Wolfgang Weisselberg Alan Browne wrote: On 2012.08.26 16:19 , R. Mark Clayton wrote: The dot pitch of my printer is 1440 and the "standard" resolution is 360 dpi. At any normal viewing distance this is imperceptible. Not when it dithers over blocks of 64 or more. What do you mean? If I print at 360 on the Epson 3800 (head is 1440) the dithering for a print dot should be no more than 4x4 (16 dithered dots). [not counting dot 'edge' to dot 'edge' dithering]. Why would it dither to 64 blocks? So how many colour steps and gray steps do you get at 16 dithered dots? I understand where you are coming from but the evidence is that the Epson 3800 printer (at least) is not confined to the regular deposition of drops in simple rectangular cells. See http://gerryeskinstudio.com/ABW_sept.../image002-.jpg Not only is it hard (?) to see any visible evidence a rectangular cell containing dot patterns, but it is evident that there need be no simple pattern of dot depositions. All I see is that the head passes over the paper several times[1], with different start timings (which explains the horizontal overlaps) and I guess the head is slightly tilted (so e.g the magenta rows are slightly shifted compared to the other rows). The diagnostic test procedure doesn't suggest the head is tilted. It's more likely to be a subtle difference in timing of the droplet spray. Horizontal, yes, vertical, no. That's either tilt or not perfect alignment of the nozzles. However, the mismatch may be tiny (less than 1/2 diameter of an ink drop), and I guess you'll not see that in the diagnostic test procedure. Presumably the accuracy with which the printer can deposit droplets must be sufficient for the claimed 2880/dpi. If I am correct in this point then the semi-random nature of the droplet pattern in the image I cited is enough to suggest that the 3800 does not use a simple cell or box pattern. with the result that overprinting causes colour-mixing and the formation of colours other than those of the raw ink. And then there is the ability of the printer to deposit drops of different sizes, although there is little evidence of this in the particular example. I don't know what the dithering algorithm is that is used by Epson but I suggest it renders moot any analysis based on simple dot patterns deposited in rectangular blocks or cells. Still, printer manufacturers give out dpi ... Buyers expect them, just as they expect megapixels in cameras. So you invent some number? 'dpi' do make some sense. The 3800 has a basic pitch of 360/dpi 360 divided by dots per inch? What's that? which can also manifest itself as 720/dpi. They also claim 1440/dpi and 2880/dpi. Some of the more recent Epson printers built around the same mechanical print engine even claim 5760/dpi. The print engine can move the paper in small increments so that you get 5760 horizontal dot 'lines' per inch (with the specific printer head). The print head can't print as dense, so the horizontal dpi value is smaller, 1440 dpi (or 1440 vertical dot lines). Presumably these subdivisions of the basic pitch are managed by software and timing in some way. Everything's managed by software these days. Once software comes into it there is no reason why dots should be deposited in positions which are simple integer fractions of the basic pitch. The limits of hardware also come into it. Let's make a simple model: Any spot on the paper can take only a given amount of ink before it starts smearing and running. Any dot from the printer has a minimum size and minimum amount of ink. Thus: there's only so many dots that can be printed in any given area on paper before there's too much ink. That gives us a good idea of dpi. There is nothing in the example I cited above which suggests that the ink/paper is anywhere near saturation. The print-pattern is predominantly white space. Irrelevant. It's a 5% gray swatch, so of course you don't get saturation YET. But what you *could* get as saturation and what you could get as an MTF depends on the dpi. [1] The ink nozzle firing repeat rate is too low to place dot on dot in a single pass. Agreed, but we are talking about the print pattern, and the number of colours it can generate. I don't think we are really much concerned about how the print pattern is generated. To understand the print pattern, we need to understand how it's generated, otherwise we'll get a "analog film has infinite resolution as it doesn't have a rectangular pixel pattern" argument. -Wolfgang -- Regards, Eric Stevens |
#13
|
|||
|
|||
Can't believe someone would say this with a straight face
Eric Stevens wrote:
On Wed, 5 Sep 2012 22:25:36 +0200, Wolfgang Weisselberg Eric Stevens wrote: On Tue, 4 Sep 2012 15:10:18 +0200, Wolfgang Weisselberg The diagnostic test procedure doesn't suggest the head is tilted. It's more likely to be a subtle difference in timing of the droplet spray. Horizontal, yes, vertical, no. That's either tilt or not perfect alignment of the nozzles. However, the mismatch may be tiny (less than 1/2 diameter of an ink drop), and I guess you'll not see that in the diagnostic test procedure. Presumably the accuracy with which the printer can deposit droplets must be sufficient for the claimed 2880/dpi. 1. There is no "2880/dpi" aka "2880 divided by Dots Per Inch". There is only "2880 Dots Per Inch", aka "2880 dpi" 2. There's no need to be more accurate than the human eye can see, unless we want to print microfilche or chip masks or something else along that line. The eye can't see even near 1440 line pairs per inch, so a little *random* scattering of each dot, say even 2 or 3 radii, doesn't impair the image. If I am correct in this point then the semi-random nature of the droplet pattern in the image I cited is enough to suggest that the 3800 does not use a simple cell or box pattern. It's much simpler to assume a tiny bit of misalignment and a bit of timing shifts as an accidental result rather than as a planned system. Still, printer manufacturers give out dpi ... Buyers expect them, just as they expect megapixels in cameras. So you invent some number? Well? 'dpi' do make some sense. The 3800 has a basic pitch of 360/dpi 360 divided by dots per inch? What's that? Well? -Wolfgang |
#14
|
|||
|
|||
Can't believe someone would say this with a straight face
On Sun, 9 Sep 2012 18:27:38 +0200, Wolfgang Weisselberg
wrote: Eric Stevens wrote: On Wed, 5 Sep 2012 22:25:36 +0200, Wolfgang Weisselberg Eric Stevens wrote: On Tue, 4 Sep 2012 15:10:18 +0200, Wolfgang Weisselberg The diagnostic test procedure doesn't suggest the head is tilted. It's more likely to be a subtle difference in timing of the droplet spray. Horizontal, yes, vertical, no. That's either tilt or not perfect alignment of the nozzles. However, the mismatch may be tiny (less than 1/2 diameter of an ink drop), and I guess you'll not see that in the diagnostic test procedure. Presumably the accuracy with which the printer can deposit droplets must be sufficient for the claimed 2880/dpi. 1. There is no "2880/dpi" aka "2880 divided by Dots Per Inch". There is only "2880 Dots Per Inch", aka "2880 dpi" OK. You are right. 2. There's no need to be more accurate than the human eye can see, unless we want to print microfilche or chip masks or something else along that line. The eye can't see even near 1440 line pairs per inch, so a little *random* scattering of each dot, say even 2 or 3 radii, doesn't impair the image. Then why does Epson (and possibly others) have dot pitches of 2880dpi and 5760dpi? If I am correct in this point then the semi-random nature of the droplet pattern in the image I cited is enough to suggest that the 3800 does not use a simple cell or box pattern. It's much simpler to assume a tiny bit of misalignment and a bit of timing shifts as an accidental result rather than as a planned system. I remember reading years ago that Epson had developed dot mixing technology. That appears to be evident in URL I cited. Still, printer manufacturers give out dpi ... Buyers expect them, just as they expect megapixels in cameras. So you invent some number? Well? I don't, but who knows about the rest? Maybe its the simplest way of expressing where they are going. 'dpi' do make some sense. The 3800 has a basic pitch of 360/dpi 360 divided by dots per inch? What's that? Well? The 'well' is where they keep the ink. -- Regards, Eric Stevens |
#15
|
|||
|
|||
Can't believe someone would say this with a straight face
Eric Stevens wrote:
On Sun, 9 Sep 2012 18:27:38 +0200, Wolfgang Weisselberg Eric Stevens wrote: On Wed, 5 Sep 2012 22:25:36 +0200, Wolfgang Weisselberg Eric Stevens wrote: The diagnostic test procedure doesn't suggest the head is tilted. It's more likely to be a subtle difference in timing of the droplet spray. Horizontal, yes, vertical, no. That's either tilt or not perfect alignment of the nozzles. However, the mismatch may be tiny (less than 1/2 diameter of an ink drop), and I guess you'll not see that in the diagnostic test procedure. Presumably the accuracy with which the printer can deposit droplets must be sufficient for the claimed 2880/dpi. 2. There's no need to be more accurate than the human eye can see, unless we want to print microfilche or chip masks or something else along that line. The eye can't see even near 1440 line pairs per inch, so a little *random* scattering of each dot, say even 2 or 3 radii, doesn't impair the image. Then why does Epson (and possibly others) have dot pitches of 2880dpi and 5760dpi? I assume Epson doesn't lie, so their printers really manage 2880 and 5760 dots per inch, at least on the average. If I am correct in this point then the semi-random nature of the droplet pattern in the image I cited is enough to suggest that the 3800 does not use a simple cell or box pattern. It's much simpler to assume a tiny bit of misalignment and a bit of timing shifts as an accidental result rather than as a planned system. I remember reading years ago that Epson had developed dot mixing technology. That appears to be evident in URL I cited. Hmm. I seem to be unable to find much about Epson dot mixing. As to dot mixing, I believe most printers will print several colours per dot (whether they are perfectly aligned or randomized in placement). The limit is whatever the paper can take ... Still, printer manufacturers give out dpi ... Buyers expect them, just as they expect megapixels in cameras. So you invent some number? Well? I don't, but who knows about the rest? Maybe its the simplest way of expressing where they are going. You could start counting dots ... then you'll know. 'dpi' do make some sense. The 3800 has a basic pitch of 360/dpi 360 divided by dots per inch? What's that? Well? The 'well' is where they keep the ink. I thought that was a cartridge ... :-) -Wolfgang |
#16
|
|||
|
|||
Can't believe someone would say this with a straight face
John A wrote:
On Tue, 4 Sep 2012 15:12:20 +0200, Wolfgang Weisselberg R. Mark Clayton wrote: "Wolfgang Weisselberg" wrote in message Alan Browne wrote: On 2012.08.26 16:19 , R. Mark Clayton wrote: So how many colour steps and gray steps do you get at 16 dithered dots? 4 dots each magenta, cyan, yellow and black = 64k ink limit. So, how many magenta steps, green steps, and gray steps do you get? Assuming each dot is either there or not there, about 16 steps each. That was the point. And I think we can agree that we can see more than 16 shades. So the area needed per pixel is larger than 16 dots. You might manage a little more if some of the colours (like cyan and yellow can print over each other, but obviously anything + black = black. Really? Anything + black = black? Try it yourself ... Ahhh... rich blacks. black + yellow = brown. -Wolfgang |
#17
|
|||
|
|||
Can't believe someone would say this with a straight face
On 19/09/2012 8:38 a.m., Wolfgang Weisselberg wrote:
John A wrote: On Tue, 4 Sep 2012 15:12:20 +0200, Wolfgang Weisselberg R. Mark Clayton wrote: "Wolfgang Weisselberg" wrote in message Alan Browne wrote: On 2012.08.26 16:19 , R. Mark Clayton wrote: So how many colour steps and gray steps do you get at 16 dithered dots? 4 dots each magenta, cyan, yellow and black = 64k ink limit. So, how many magenta steps, green steps, and gray steps do you get? Assuming each dot is either there or not there, about 16 steps each. That was the point. And I think we can agree that we can see more than 16 shades. So the area needed per pixel is larger than 16 dots. You might manage a little more if some of the colours (like cyan and yellow can print over each other, but obviously anything + black = black. Really? Anything + black = black? Try it yourself ... Ahhh... rich blacks. black + yellow = brown. But brown isn't a colour: http://upload.wikimedia.org/wikipedi..._brown.svg.png |
#18
|
|||
|
|||
Can't believe someone would say this with a straight face
Me wrote:
On 19/09/2012 8:38 a.m., Wolfgang Weisselberg wrote: John A wrote: On Tue, 4 Sep 2012 15:12:20 +0200, Wolfgang Weisselberg R. Mark Clayton wrote: "Wolfgang Weisselberg" wrote in message Alan Browne wrote: On 2012.08.26 16:19 , R. Mark Clayton wrote: So how many colour steps and gray steps do you get at 16 dithered dots? 4 dots each magenta, cyan, yellow and black = 64k ink limit. So, how many magenta steps, green steps, and gray steps do you get? Assuming each dot is either there or not there, about 16 steps each. That was the point. And I think we can agree that we can see more than 16 shades. So the area needed per pixel is larger than 16 dots. You might manage a little more if some of the colours (like cyan and yellow can print over each other, but obviously anything + black = black. Really? Anything + black = black? Try it yourself ... Ahhh... rich blacks. black + yellow = brown. But brown isn't a colour: http://upload.wikimedia.org/wikipedi..._brown.svg.png Neither white. And yet the paper's white. Your point? -Wolfgang |
|
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
[SI] And a new mandate, straight to you! | Al Denelsbeck | 35mm Photo Equipment | 8 | April 20th 06 09:19 AM |
SWC - what's the straight scoop? | jjs | Medium Format Photography Equipment | 12 | December 4th 04 07:19 PM |