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Author Topic: Camera Raw (Real World) and Resolution  (Read 9940 times)
jbrembat
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« Reply #20 on: February 20, 2008, 02:39:13 AM »
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dmward
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That is ancient history in the technology business
If you are able to understand it, you can download the kit for drivers building of Epson. This is not out of date.
You get the same numbers.

Farmer
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Everyone seems to think that a driver can only accept 1 input value to work out the output
This is exactly how any printer driver works, not only Epson.
Dithering is the process that connects PPI to DPI, but input pixels are sampled at a definite rate (depending on driver settings).

Jacopo
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Farmer
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« Reply #21 on: February 20, 2008, 05:26:30 AM »
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This is exactly how any printer driver works, not only Epson.
Dithering is the process that connects PPI to DPI, but input pixels are sampled at a definite rate (depending on driver settings).
[a href=\"index.php?act=findpost&pid=176143\"][{POST_SNAPBACK}][/a]

Yes, based on driver settings - there's no single magical number for all print jobs.  It's also rather more complicated (particularly with the work in the new LUT for the R1900 which will flow through to other printers, for example) than just sampling back to 360 (or 300 or 600 or 720).  How the printer decides to get the data it wants to fill the matrix is device specific, which means it's going to be better than some software just doing the sampling for you that knows nothing about the capabilities of the printer.

That's why the printer company engineers are telling us leave your image between 180 and 480 and send it to the printer.
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jbrembat
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« Reply #22 on: February 20, 2008, 06:11:01 AM »
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Yes, based on driver settings - there's no single magical number for all print jobs.  It's also rather more complicated (particularly with the work in the new LUT for the R1900 which will flow through to other printers, for example) than just sampling back to 360 (or 300 or 600 or 720).  How the printer decides to get the data it wants to fill the matrix is device specific, which means it's going to be better than some software just doing the sampling for you that knows nothing about the capabilities of the printer.

That's why the printer company engineers are telling us leave your image between 180 and 480 and send it to the printer.
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You don't pay attention to my words.
I quote myself in this same thread:
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Just to clarify another thing.
"Native resolution" does not exist.

Some numbers for my Canon printer :

600 PPI for high quality
300 PPI for low quality
619 PPI for high quality, borderless 4x6
615 PPI for high quality, borderless 5x7
609 PPI for high quality, borderless A4
And in another thread:
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I know that large format Epson printers use a PPI value of 360.
I am not sure if 11880 follows this rule, you can check it.

If 360 is the right value then 180=360/2 may be good enough, 360 is the best.
The 240 value is a good value for Epson desktop printers (240=720/3), but 360 is better and 720 is the best.

Sampling is performed before dithering, so the best thing to do is resampling to the driver PPI value.
Dithering may alleviate artifacts apparence from printer driver resampling more or less.

To check the 11880 PPI go to my web site and download PrinterData (Windows application).
[a href=\"http://www.photoresampling.com/index_eng.php]http://www.photoresampling.com/index_eng.php[/url]
The LUT you are referring to is to compute the conversion from RGB to percentage of inks. This is off topic.

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which will flow through to other printers
What does it mean Huh

Jacopo
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Farmer
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« Reply #23 on: February 20, 2008, 07:03:35 AM »
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Yes, I did read.  I understand that you produce software for resampling images for printing so you have a certain agenda to push.  That's fine, btw, I'm not criticising you or suggesting anything negative about your software (in fact, it's well reviewed from what I've seen).

I know what the LUT is for, the point is that the entire process is more complex than some people (note - I've made a point of being broad in my comments because they are NOT targetted at you specifically) choose to suggest.

You need to stop taking comments made in a public thread to be solely directed at you, mate.  They're not.  They're general comments made regarding the entire discussion.

Your utility reports the 11880 at 360 unless "Finest detail" is ticked in the driver in which case it reports 720.  No surprises there.

What you're apparently suggesting, having read through your site, is that your resampling gives a better result than sending images to the printer at other ppi or resampling using the likes of Photoshop.  I haven't tested your software, so I can't comment.

When I have time, I'll install your software and do some prints and run some blind tests to see if people can pick the differences.

My recommendation, though, is that people send data anywhere from 180 to 480 and they will have excellent results and won't be able to pick the difference except under a loupe.  In fact, 120 is fine in some cases, but I would avoid it generally.

FWIW, I'm not guessing about this stuff, but doing the test with your software will be interesting for sure.
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jbrembat
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« Reply #24 on: February 20, 2008, 07:57:45 AM »
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You need to stop taking comments made in a public thread to be solely directed at you, mate.  They're not.  They're general comments made regarding the entire discussion.
[a href=\"index.php?act=findpost&pid=176159\"][{POST_SNAPBACK}][/a]
My comments are not directed to me.
I tried to explain how a printer works.
A driver do 3 things:
 1. sample the image to pick up pixels color
 2. translate the RGB data into ink percentages (the LUT)
 3. apply a dithering algorithm to simulate the colors

Mxing this 3 steps is to make anything foggy.
Is the general discussion devoted to clarify how printers work?
I gave a well documented contribute. You can't say the same for others.
I think you should be happy if someone try to explain something without saying : "trust me, do that. It is the best that you can do".
In any case, you and everyone, are free to close eyes and brain and believe any undocumented and obscure explanation.

Jacopo
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Farmer
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« Reply #25 on: February 20, 2008, 08:59:02 AM »
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In any case, you and everyone, are free to close eyes and brain and believe any undocumented and obscure explanation.

Yeah, 'cause that's a great way to promote your software, by calling anyone who disagrees with you names.

Perhaps you can provide some of that well documented evidence to back up the claim on your website that your resampling algorithm is better than anyone elses?
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digitaldog
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« Reply #26 on: February 20, 2008, 09:09:21 AM »
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Perhaps you can provide some of that well documented evidence to back up the claim on your website that your resampling algorithm is better than anyone elses?
[a href=\"index.php?act=findpost&pid=176174\"][{POST_SNAPBACK}][/a]

Out to print please (and on a number of subjects). I've tried all kinds of such software, haven't found any yet that in anything other than a toss up were "better" than using Photoshop and when they are, its nearly impossible to see on print (and hardly visible on screen). Yet I hear all kinds of users of products saying "I blew up this image XXX% and look how good it looks" (never anywhere as good as using real data and never next to the same print made with upsizing and proper subsequent sharpening in Photoshop).
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Andrew Rodney
Author “Color Management for Photographers”
http://digitaldog.net/
jbrembat
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« Reply #27 on: February 20, 2008, 09:36:00 AM »
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Yeah, 'cause that's a great way to promote your software, by calling anyone who disagrees with you names.

Perhaps you can provide some of that well documented evidence to back up the claim on your website that your resampling algorithm is better than anyone elses?
[a href=\"index.php?act=findpost&pid=176174\"][{POST_SNAPBACK}][/a]
I am not promoting anything. I was speaking about printer drivers. You introduced the resampling algorithm  that is off topic as was the LUT.

Jacopo
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Farmer
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« Reply #28 on: February 20, 2008, 02:23:24 PM »
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On your website (to which you referred me) you state, "GBLS is my own algorithm which, offers better results than all other common algorithms."

You're the one claiming that the driver samples at a fixed rate and that providing data at that rate gives the best results.  You also make the above claim.

I'm going to test your software - I'm fortunate enough to have access to a wide array of printers.

The point I have been making (and admittedly not as well as people like Jeff and Andrew who are more used to doing this) is that the drivers are designed to work within a range, not a single value, and providing data anywhere within that range will give you acceptable results - results that are superior to user-resampling to some specific resolution before printing.  You claim otherwise.

Since you seem to not want to discuss this further, I'll do some testing.
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Farmer
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« Reply #29 on: February 20, 2008, 05:11:27 PM »
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Well I was going to test it here at work, but the demo version does not allow file saving or printing (and splashes the word "demo" dozens of times all over the image).

I understand the need to protect your software, but a demo that can't actually be demonstrated is difficult to evaulate - indeed, there's no way to verify or dispute your claims without first paying you...

So, as far as I can see there's no way to test this without paying the 55 Euro to buy it, which I'm not going to do.

Oh well.
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PeterTinson
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« Reply #30 on: February 21, 2008, 04:39:45 AM »
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Epson drivers do interperlate to 360 ppi.
This can be demonstrated by either having an image that has a repeating pattern of lines such as corigated iron or even paterned suiting material.
Or setting up in photoshop a document with close lines in a pattern.
If these are processed at 300PPI and printed the is a strong liklyhood that there will be an interferance paterns visible, if processed at 360ppi these paterns are not there.
Peter
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PeterT
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« Reply #31 on: February 21, 2008, 07:10:43 AM »
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Epson drivers do interperlate to 360 ppi.
This can be demonstrated by either having an image that has a repeating pattern of lines such as corigated iron or even paterned suiting material.
Or setting up in photoshop a document with close lines in a pattern.
If these are processed at 300PPI and printed the is a strong liklyhood that there will be an interferance paterns visible, if processed at 360ppi these paterns are not there.
Peter
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The 360 ppi figure is often given for Epson printers. [a href=\"http://www.rags-int-inc.com/]Rags Gardner[/url] has done some interesting experiments with the Epson 2200 by printing images with a grid pattern and observing the interference patterns that result. On his site, go to the technology, injket tabs to reach the post. According to his results, the Epson 2200 has a native resolution of 288 ppi. This resolution is determined by the physical spacing of the printer nozzles, which is fixed in the direction perpendicular to the print head, but can be varied by the printer stepper in the direction of movement of the print head. The software interpolation may not match the hardware resolution with some printers, so there is a further complication.

In his Real World Sharpening book, Bruce Fraser refers to the above resolution as the addressable resolution of the printer. He states that some pundits claim to get better results by printing at even multiples of the printer's native resolution, often assumed to be 360 ppi for Epson, and this does apply to targets containing line pairs but in real world photography there is little difference. Indeed, he states that  resampling of the image to the "native resolution" may do more harm than good.

Within limits, he recommended printing at the native capture resolution without resampling. Those who resample to the "native" printer resolution or some multiple thereof have to know the native resolution, and it may not be what they think it is.
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