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Need comments: What I understand about inkjet printer resolution...


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roygoh

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Hi,

The latest inkjet printer models have resolution in the 1200 or even 2400 dpi range.

On reading a book on colour correction (Professional Photoshop 5: The Classic Guide to Color Correction, Dan Margulis), the section on printing resolution led me to believe that the DPI rating given for an injet printer is, literally, "dots per inch".

This is the number of fixed sized ink dots the printer can put down on a 1-inch long line on the paper, which is different from the DPI setting in Photoshop, which actually means Pixels Per Inch (PPI).

Since inkjet printers use half-toning to control the intensity of a particular ink colour at a particular area (pixel) on the paper, it requires a pixel area that is equal to or greater than the area taken up by 256 dots in order to be able to deliver 256 levels of intensity of the ink in that pixel, to match up with the 8-bit picture data that is sent to it (disregarding colour profiling).

And area of 16 X 16 dots will provide the printer enough space to deliver 256 levels of intensity. Which means that for the 1200 DPI printer, the printing resolution should be 1200/16 = 75 pixels per inch, if you want a colour resolution of 8-bits per channel per pixel.

Printing at higher ppi may result in better line resolution (sharper prints), but because the pixel area is not enough for the printer to put it 256 dots of ink, the trade-off is in getting lower colour resolution.

For example, if I have a 3000X2000 picture, and I want to generate a 10 by 6.6 inch print on a 1200 dpi printer, which way is better:

- set the "ppi" in photoshop to 300 and keep the resolution at 3000X2000, or
- set the "ppi" in photoshop to 75, and reduce the reolution to 750X500

The first scenario seems to be sharper, in principle, than the second, but since the pixel area is only enough for the printer to put in 4X4 = 16 dots, the colour resolution I get is than 16 levels per channel per pixel.

In a nutshell, my understanding is that if I set the ppi beyond 75 on a 1200 dpi printer, I will sacrifice colour resolution per pixel.

I understand I muct have over-simplified the issue somewhere. For example, the role of the photo cyan and photo magenta inks in 6-colour printers. Would appreciate the feedback from other printing experts here.

Thanks!
 

Jed

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Roy I'm explaining this to you via pm. If anyone else wants to know the answer, ask me.
 

Darren

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#7
hey Jed, share share ler ....
 

K

koktong

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Jed, I am interested to know too. What roygoh says make sense to me.
 

Jed

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#11
$@$@#

Yes it's a secret. I've got a big fan club at the moment which is why I'm being secretive. And I suppose I have to go along with Ian too, in protecting my own trade position hehe. (Hence, mental note to self, never bother trying to argue the positives of digital ever again.)
Seriously though, let me make sure I've answered Roy's question before I go spouting off and misleading people.

Roy, I've re-read your post and suspect that I've misinterpreted your question the first time around. A new pm will be on its way to you in a bit.
 

tsdh

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#12
Originally posted by Jed
Yes it's a secret. I've got a big fan club at the moment which is why I'm being secretive. And I suppose I have to go along with Ian too, in protecting my own trade position hehe. (Hence, mental note to self, never bother trying to argue the positives of digital ever again.)
If the article is good (and not a trade secret..:bsmilie: ) then why not post it in the CS article column, so that others can learn too.
Today many people are printing their images at home, and most of them using ink-jet printer. To get the most out of their printers, they need to learn about digital image printing, rather than left it at factory default.
I use photo quality ink-jet printer for many years to proof-print my images (for final prints, I still prefer dye-sub printers..). Ink-jet quality increase steeply in the past few years (in fact, I change my printer every year in the past 4 years), and now I don't complaint much about its resolution, it is good enough for our eyes. With 2400dpi and 6 ink-colors, they can produce adequate pixels.
My only hurdle now is on the calibration side. If somebody know the easy method to calibrate monitor-to-printer consistency then please I want to hear that. (But not using expensive profiler s/w such as OptiCal or ColorBlind+Chroma4.)
 

Richard

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#13
Originally posted by tsdh
My only hurdle now is on the calibration side. If somebody know the easy method to calibrate monitor-to-printer consistency then please I want to hear that. (But not using expensive profiler s/w such as OptiCal or ColorBlind+Chroma4.)
No, I think most people would rather not reply to you. It's quite hard to tell when you have a genuine question, or when you already know the answer and are just asking questions so as to flaunt your advanced knowledge.
 

Darren

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#14
Originally posted by tsdh
My only hurdle now is on the calibration side. If somebody know the easy method to calibrate monitor-to-printer consistency then please I want to hear that. (But not using expensive profiler s/w such as OptiCal or ColorBlind+Chroma4.)
There is no easy method to calibrate monitor-to-printer consistency - the hard way is to play with the printer settings and keep on printing/recording/adjusting until you are satisfied.

Even the printer calibration software (eg. ProfilerPlus from ColorCal) is not exactly easy to use.
 

tsdh

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#15
Originally posted by Richard
No, I think most people would rather not reply to you. It's quite hard to tell when you have a genuine question, or when you already know the answer and are just asking questions so as to flaunt your advanced knowledge.
I don't know the answer yet. Of course I'm trying to ask around, but their answers are varied and I'm not confidence about.
What I do now, is not scientific, and not accurate: by printing a test image (Kodak Q60), then adjust the printer driver. I still do not know how to create an ICC profile for my printer or my monitor to make it consistent. Or are there any better way. (I'm only printing images from Photoshop or Pagemaker)
So I would like to look for alternative methods to calibrate, by listening to other people suggestion, digest/discuss it, to achieve the easiest yet accurate method (if possible).

... don't always worry and suspicious (.. as Jed do :) )...
but again, I don't treat you, CK, Jed, Ian or other members like an advisor or consultant, but rather as somebody who well knowledgeable and commited to the world of photography (within his interest and limit), who do not hesitate to explore further possibilities. So others can benefit.

So far, I found ClubSnap is the best local photography forum where newbies and expert all around and gather together (even somehow better than the previous Asiaphoto.com ). Flare, friction, argue, are common in a discussion, that's the role of moderators of the forum to safeguard so that it would not go beyond limit. Sorry that last time I "kicked" Jed a bit to see his reaction as the "super-power" of the forum :)
If I allowed to suggest; don't drive the forum into Question-and-answer kind, but encourage every individual whether newbie or expert, to be willing to discuss and express his/her passion in photography, which I already see in this forum. Good work.
 

Jed

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#16
Originally posted by tsdh
... don't always worry and suspicious (.. as Jed do :) )...

(snipped)

... Sorry that last time I "kicked" Jed a bit to see his reaction as the "super-power" of the forum :)
Wait. So you're saying you purposely provoked me before, and then criticise me for being suspicious and worrying? Right...

*Sigh* I'm getting too old for this.
 

tsdh

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#17
Originally posted by Jed
Wait. So you're saying you purposely provoked me before, and then criticise me for being suspicious and worrying? Right...
*Sigh* I'm getting too old for this.
Not that Jed. I just curious and want to know how a 'forum authority' (moderator) will do if somebody being 'nasty' to him, in the sense; pressurise him in knowledge.

I observed CS for sometime, and appreciate it. Many experts and many newbies here, all don't hesitate to express their photographic passion, that's good. But slowly the forum may lead into "question-and-answer" type, where the expert is like a doctor waiting for a patient to come for consultation. (.. and usually the doctor doesn't like second opinion from his patient :) ).
Traditional (or formal) photographic organisation, rely on meetings for their inter-member communication, with some of the people is more interested to show off their luxury photographic gadgets. This situation will deter beginners who really interested in photography.
An online forum like CS, has a very extensive inter-member communication and minimal meetings. Not an interesting place for equipment showcase, but can be a good place for beginners to grow up. But it all depend on the 'super-powers' controlling the forum. That's why you're an important person Jed... :)
continue your good work...
 

#18
Originally posted by tsdh


Not that Jed. I just curious and want to know how a 'forum authority' (moderator) will do if somebody being 'nasty' to him, in the sense; pressurise him in knowledge.

I observed CS for sometime, and appreciate it. Many experts and many newbies here, all don't hesitate to express their photographic passion, that's good. But slowly the forum may lead into "question-and-answer" type, where the expert is like a doctor waiting for a patient to come for consultation. (.. and usually the doctor doesn't like second opinion from his patient :) ).
Traditional (or formal) photographic organisation, rely on meetings for their inter-member communication, with some of the people is more interested to show off their luxury photographic gadgets. This situation will deter beginners who really interested in photography.
An online forum like CS, has a very extensive inter-member communication and minimal meetings. Not an interesting place for equipment showcase, but can be a good place for beginners to grow up. But it all depend on the 'super-powers' controlling the forum. That's why you're an important person Jed... :)
continue your good work...
I see, so you actually go around taunting people into arguments and the like eh? Just like what kids would do trying to push their luck with their parents/teachers (e.g. see how late he can come home before getting a scolding) that sort of things?

I got something more fun for you. Whack a policeman on the back. Or just use a long stick to poke him. :)

Please refrain from doing this in this forum. It's not very healthy.

Regards
CK
 

tsdh

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#19
Originally posted by ckiang
I see, so you actually go around taunting people into arguments and the like eh? Just like what kids would do trying to push their luck with their parents/teachers (e.g. see how late he can come home before getting a scolding) that sort of things?
I got something more fun for you. Whack a policeman on the back. Or just use a long stick to poke him. :)
Regards
CK
No. That's different kind of acts.
I don't disturb people for my own benefits, nor for fun.
 

Darren

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#20
Originally posted by tsdh
An online forum like CS, has a very extensive inter-member communication and minimal meetings. Not an interesting place for equipment showcase, but can be a good place for beginners to grow up.
Not quite true - for ClubSNAP, we try to emphasize more on face-to-face meetings with the forums acting as a catalyst for those meetings. Witness the many threads and posts on regular outings and SEEDs. And we plan for more formally organised meets in the future. You should try to attend (if you are in Singapore that is) and get to know the members (and occasionally mods/Founding Members) personally. Of course, at the meetings, we also talk mainly about photography but at least the chance for a real friendship to grow is there.

But it all depend on the 'super-powers' controlling the forum.
Just to clarify - no single 'super-power' controls (I really hate the word control - we have never tried to, and will never control things in ClubSNAP) the forums in ClubSNAP. Decisions are made collectively (behind the scenes) by mods and Founding Members.

Every one (members, mods and Founding Members) is individually responsible for their words and actions in ClubSNAP. Just as if a mod or Founding Member posts a comment on a thread, that post is a statement of the individual's experience and opinion, and not necessarily as a collective norm. We are not the Borg, you know ... ;)
 

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