8-bit vs 1-bit resolution?

[lfelton]

Xerox high end kit (i.e. iGen4) has a resolution of 600x600dpi 8-bit whereas the lower end kit has a resolution of 2400x2400dpi 1-bit.

I've asked a couple of sales people at Xerox what the actual technical difference between these two is, but no-one seems to know.

Can anyone explain what the difference is in actual technical terms?

 

[random]

I must admit I have trouble getting my head around this one also. 1-bit only has two states on or off. Where as 8-bit has 256 'states'. I can only take a stab in the dark here and say that the 1-bit machine has the same dot size but each colour is created by how close the dots are together at the same size. For the 8-bit the dots are all exactly in the same place but the size of the dot is greater or smaller to create your colour. So the laser unit has 256 'steps'.

At the end of the day you need to spin something to get the punter to beleave that although 1/4 the resolution the i-gen is a great investment at 4 x the price. But 256 x 1 or 1 x 256 is always going to equal 256.

 

[michaelejahn]

resolution - 1440 max, most likely interpolated

resolution - 1440 max, most likely interpolated

Xerox high end kit (i.e. iGen4) has a resolution of 600x600dpi 8-bit whereas the lower end kit has a resolution of 2400x2400dpi 1-bit.

I've asked a couple of sales people at Xerox what the actual technical difference between these two is, but no-one seems to know.

Can anyone explain what the difference is in actual technical terms?

Resolution 600 x 600 dpi x 8-bit

The actualy questions is;

"what is the resolution of the actual marking engine"

if it is 600 x 600...

- that would be that they can place two marks 1/600th of an inch apart, and that these marks are 1/600th of an inch in diameter - they can easily do that.

Now - having said that - I would rather doubt that they can create a checkboard pattern of small squares each 1/600th on an inch in size (see the difference) - and I would be stunned to learn that the iGen 4 can make 2 spots on a peice of paper that are 1/2400th of an inch in diameter - and 1/2400th of an inch appart - of course, I would love to be shown photomirographs and proven wrong - or be able to take the photomicrographs myself and post them !

 

[random]

Assume you have a 4 square pieces of paper. One side each square is black the other is white. Then you could turn over One square, then two squares then three squares then four. From a distance our eyes won't see this as a black square next to white ones but different shades of grey. So from 1 change (1 bit) we have achieved 4 different levels of grey. Do this for CMYK and you would have a box 16x16 or 256 colors. Obviously with printing these dots can sit on top of each other and be closer and further apart so technically 2400dpi could actually be 4 x 600 dpi which is a tad misleading. However I suspect that each colour has 4 laser diodes writing at 600 dpi per colour (in a 2400 dpi machine).

So for 8-bit it would be more like the screen you are looking at. The pixels on your screen can't move so they go lighter or dimmer to represent a colour. Think of a dimmer control of a incandescent lamp. Being digital you are restricted to bit depth I-GEN has been around for years so the technology at the time probably only extended affordably to 8 bit processing or 256 grey levels. The technology is probably available now for 12bit (4095 levels) but then you start having physics problems like toner, not to mention the massive files you would need to take advantage of the range.

I would have thought resolution would be more of an advantage than 8-bit processing but I guess this r&d will lead to a 2400dpi 8-bit machine.

 

[X33]

this one is hard to explain. trying to make it simple :

600x600x8 :
- it uses a 2 beam laser
- it can produce 2,880,000 addressable dots per inch

2400x2400x1 :
- it uses a 32 beam laser
- it can produce 5,760,000 addressable dots per inch

mathematically (I have all the documentation), quality is better, because you have more dots per inch and you still can produce 256 levels of color by providing sharper edges, better midtones, etc. I think it's visible to the naked eye; but, quality is always subjective.

I believe Xerox is the only one with 2400x2400dpi technology, it's called VCSEL.

the Xerox iGen is a special case, I'm not an iGen expert, but as far as I know, there's a lot more technology in that press that makes the quality be much better even though it is 600x600x8. If you are interested in an iGen, contact Xerox.

 

[aferrer]

this one is hard to explain. trying to make it simple :

600x600x8 :
- it uses a 2 beam laser
- it can produce 2,880,000 addressable dots per inch

2400x2400x1 :
- it uses a 32 beam laser
- it can produce 5,760,000 addressable dots per inch

mathematically (I have all the documentation), quality is better, because you have more dots per inch and you still can produce 256 levels of color by providing sharper edges, better midtones, etc. I think it's visible to the naked eye; but, quality is always subjective.

I believe Xerox is the only one with 2400x2400dpi technology, it's called VCSEL.

the Xerox iGen is a special case, I'm not an iGen expert, but as far as I know, there's a lot more technology in that press that makes the quality be much better even though it is 600x600x8. If you are interested in an iGen, contact Xerox.

I think there's an error in your math. 8-bit means the dot size can be gradated in 256 levels.

256 levels can be obtained with a 16x16 dot grid (this would be the equivalent in addressable dots).

So your math for the case of the iGen3 should be: 600x600x16= 5,760,000 addressable dots (coincidentally the same "addressability" than 2400x2400x1.

Anyway, there's a very interesting short article by Frank Romano entitled "Digital Color Printing Specs" (link below) which helps decipher Manufacturers Specs. A common error is to consider that the Higher the Resolution, the Higher the Quality (this is not necessarily the case). It's actually Xerox Sales Reps most overused argument.

Try WhatTheyThink Premium Access

 

[michaelejahn]

FujiXerox VCSEL and resolution

FujiXerox VCSEL and resolution

VCSEL - Vertical Cavity Surface Emitting Laser - is indeed part of the solution - the more important part is the ROS (raster output scanner) - this is a FujiXerox technology - FUJI XEROX CO.,LTD. | Home

While this is part of the 2400 story - it is the LED print head that does the 'marking'

Electro-photography printers and photocopiers form latent images by exposing a charged photoreceptor drum to dots of light. This is a two part two image-writing system and is generally used to form latent images: a raster output scanner (ROS), which uses a laser and rotating polygon mirror, or an LED printhead, which incorporates a light-emitting diode (LED) as a light source.

Since LED printheads do not require a scanning optical system, they offer certain advantages over the conventional and widely deployed ROS system, including smaller dimensions and essentially noise-free operation. However, LED printheads also feature certain disadvantages, including the difficulty of maintaining uniform exposure due to the LED printhead’s many light sources. There are also additional difficulties in maintaining uniform print density.

My read of the technology here is that while they can claim a point of light of 2400 - there is a 1200 interval between these point - so, to me, that means that the smallest space between to 'spots' would be 21 microns - so - 1200 would be the best they could do in one direction.

I am not an engineer, nor cerainly DO NOT have anything bad to say about Xerox here - it is an amzaing feat in engineering !

That being said - just because a light valve can show that I could indeed make a spot of light even as small at a 2400th of an inch - in the Xerox device, even if the tone particle(s) is very small - you must then realize that the process includes a technology for belt fusing/melting adhesion and cooling before stripping (MACS technology) - so, you are tossing some stuff onto a surface, melting that and then fusinging that (heat, roller type of fusing). Besides that - This system has a very tricky problem related to registration - this required Fuji Xerox to develop a digital image registration control technology IReCT (Image Registration Control Technology)

but in almost all cases, the path between a 2400th of inch in a PDF and a spot that is 2400th of an inch on a piece of paper is very complex and hard to really describe - as it involves thousands of technologies - not just one 'makes' this happen. In the end, just like that old "Square Spot" Creo argument, it matters little as to what the laser can do - it is all about how the mark (or spot) of ink, pigment or toner is "applied" to that very rough textured surface - paper - I mean, take a look at a photomicrograh of paper - it is like trying to draw on burlap !

http://chempatec-auhorn.com/images/coatpapersurface_480.jpg

 

[random]

I will roll with the article posted before. 600 dpi is 41microns. The human eye can not see below 40 micron, why kill an ant with a sledgehammer.

 

[michaelejahn]

I will roll with the article posted before. 600 dpi is 41microns. The human eye can not see below 40 micron, why kill an ant with a sledgehammer.

i just wanted to make sure that ant was dead.

btw - i have no idea why i am listed as a senior member - i am only 53 years old. - what is the next level after senior ?

ancient ?

 

[meddington]

btw - i have no idea why i am listed as a senior member - i am only 53 years old.
ancient ?

maybe it should be Señor, compadre.

 

[Craig]

maybe it should be Señor, compadre.

Now that's Tequila talk!!!

 

[Its Not a Copier]

Funny video that talks about the 2 DPI

YouTube - hizbub PRESS C8000 vs. Smearox 800

 

[gordo]

In the end, just like that old "Square Spot" Creo argument]

LOL - You have no idea how long I kept sheets of micro printing to show you just how small type could be reproduced on a standard sheetfed press:

Compared to a period:

Compared to text on a penny:

best gordon p

 

[Craig]

Nice Gordo! What point size would you figure that to be???

 

[salesserviceguy]

I think much of what is said is Marketing from different copiers vendors trying to create a Proprietary dot pattern. See attached Technical discussion from Konica Minolta. In the end, the human eye can not see below 40 microns and a 600 x 600 DPI, 8 bit RIP is just fine

 

[gordo]

Nice Gordo! What point size would you figure that to be???

The "CREO CREO" text was just under 1/4 point high.

best, gordo

 

[gordo]

See attached Technical discussion from Konica Minolta.

Errrr...each page of the document that you posted has "CONFIDENTIAL – Internal Training Document Only Not for distribution" Are you sure it was a good idea to post it?

best, gordo

 

[salesserviceguy]

Please post. It is an authentic document.

 

[salesserviceguy]

If posting this document is contrary to any kind of Print Planet editorial policies, I would not want to cause an issue.

Thanks

 

[fiatlux]

If posting this document is contrary to any kind of Print Planet editorial policies, I would not want to cause an issue.

I doubt that this is just a question of PrintPlanet policy. Publishing a document that specifically states that it is "CONFIDENTIAL – Internal Training Document Only Not for distribution" would be a breach of trust (unless perhaps if you're Julian Assange of Wikileaks). Also it might put the web site that you used to publish the document on at legal liability.

So, if it says "CONFIDENTIAL – Internal Training Document Only Not for distribution" - don't distribute by publishing it on a public forum.

FL