View Full Version : Effects of Epson printer's native resolution

Robert Ludlow
10-Oct-2004, 13:34
Hi, this is my first post here. In earlier posts, members stated that the Epson Ultrachrome printers upscale lower resolution files to 360 ppi. So the question that occurs to me is how good a job of interpolation does the printer's driver do? Maybe I'm better off doing my own interpolation using Photozoom Pro, which seems to do a very good job. Recently I had an old digital image I wanted to print large, and I upsampled it from 117 ppi to either 180 or 240 (I'm too lazy to look for the file) before printing it on my Epson 7600. Would I have done better to go all the way to 360? Or are they saying that if I had sent it to the printer at 117, the driver would have interpolated it up to 360 and it would have looked just as good as the file I iterpolated up to 180 or 240? Thanks for your help with this; hope it's not too confusing.

10-Oct-2004, 13:54
Whut? Huh?

Robert Ludlow
10-Oct-2004, 14:34
Sorry, I was afraid I might not have been clear, so I'll try again. Two recent posts on this forum stated that when you send a file to one of the Epson Ultra-chrome printers, unless your file's resolution is 360 ppi, the Epson driver resamples it to 360 ppi. One of the gentlemen referred to this as the Epson driver's native resolution. He went on to say that if the file you send is 360 ppi, then the printer prints it 360 ppi, or pixel for pixel. In the past, when I wanted to make a large print on my Epson 7600, if the file's resolution was lower than 180 ppi, I would always upsample to 180 or 240 ppi. My question is this: If Epson's printer driver is going to upsample every file that's lower than 360 ppi, maybe I should upsample to 360 rather than 180 or 240. I use Photozoom Pro for interpolation, and it seems to do a very good job. So why not use Photozoom, unless Epson's driver does a better job of interpolation (i.e., upsampling). A related question is, why upsample my 120 ppi file at all? If the Epson driver is going to make it 360 ppi, why not just leave it at 120?

Bruce Watson
10-Oct-2004, 15:03
You can leave it and let the driver do the upsizing. That's what it's there for.

But... you can also do some testing. Print the image twice. One letting the driver upsize, and the other you do the upsize in your image editor of choice. See what you think.

Robert Ludlow
10-Oct-2004, 17:52
Thanks, Hogarth, I will do some testing. Earlier this year there were several lengthy discussions on Yahoo's Epson Wide Format forum about this issue, and it's an understatement to say that there was a wide range of opinions about what resolution is best when printing on an Epson wide-format printer. One person swore by 720 ppi; another pointed out that Epson recommends 300 ppi. So your answer--the printer upsizes everything lower than 360--seems blessedly simple. All I knew before was that many knowledgable people recommended an even multiple of 720. So now I'm having a hard time understanding the purpose of interpolating lower-resolution files. Suppose I want to make a 24 x 36 print of a file that comes out to just 100 ppi at that size. What I have done in the past with some success is to use PhotoZoom Pro (formerly S-Spline Pro) to res that file up to 180 or 240 ppi. But if I properly understand your point, when I send it to print, the Epson driver further interpolates it to 360 ppi. So are you saying I should just print at 100 ppi and let the Epson driver take care of upsizing? I'm going to try that, but it seems really counter-intuitive and I suspect the file I upsample will look much better.

Matthew Parker
10-Oct-2004, 19:28
This is my first post here but I think I have something useful to contribute.

I have an Epson 7600 and have found answers to many questions on the epsonwideformat yahoo group. It seems if i remember correctly that there was a long discussion about this very question some time back so if you do a search there you are likely to find an answer.

Matthew Parker

Bruce Watson
10-Oct-2004, 22:13
But if I properly understand your point, when I send it to print, the Epson driver further interpolates it to 360 ppi. So are you saying I should just print at 100 ppi and let the Epson driver take care of upsizing?

That's what I'm saying. People have done the tests - they send the Epson driver files at 359dpi, 360 dpi, and at 361 dpi, and can see the difference (the 359dpi and 361dpi both get resized to 360dpi, while the 360dpi image is printed untouched). I've tried it, and I can see the difference. I put the prints on the wall side-by-side, and my wife picked the 360 dpi one as the better print without knowing what the difference was.

It's not much of a difference really. If the prints aren't side-by-side, you won't know that anything is different. But it's a simple test to make; I advise that you do it yourself and see what you think.

Now, I've got to point out that sending 100 dpi information to the printer is going to result in a low resolution print no matter what does the upsizing. Upsizing creates more data, but it doesn't create more information. You aren't miraculously going to be able to read the sign down the street, or have the tree branches etched sharply against the sky. I'm sure you already know that, but I'm just saying...

Finally, I should point out that this is an Epson driver thing, not an Epson printer thing. If you use a RIP like StudioPrint, the RIP isn't going to resize anything (I've done the same test with StudioPrint, and everyone thinks the three prints are identical). The RIP will just convert what you send it into little dots on the paper to the best capabilities of the print engine. The Epson driver could do this, but it resizes to 360dpi (or 720 dpi, depends on the printer apparently) first. We don't know why.

Ken Lee
11-Oct-2004, 08:39
Every time you up-size or down-size (or even just save the image) to a different resolution, some detail gets tossed out as pixels are interpolated. If we take this argument to its logical conclusion, then wouldn't it be best for the original image to be gathered at a multiple of 360 ? That way, there would be the least amount of loss.

So tell Epson you want to scan at 3240, not 3200 ppi ! I'm only half-serious, but it makes some sense. That's why re-sizing the image to print, followed by sharpening, are the last 2 operations to perform in a careful digital workflow.

chris jordan
11-Oct-2004, 14:15
Robert, there is a difference between the interpolation algorithm in the Epson driver, and the interpolation algorithm in Photoshop. Photoshop's is better for several reasons, so do all of your resizing in Photoshop. If you do side-by-side test of detail-rich images (such as diagonal one-pixel lines on distant telephone lines) you will see stair-steps in the print made using the printer driver's interpolation, that are smooth in the image resized in Photoshop.

It is also beneficial to do your sharpening at the final output resolution, after you have sized the print to 360 dpi; otherwise artifacts such as edge halos will be enlarged by the driver's interpolation, making your prints lower quality than they could be.

So, the workflow is: do your Photoshop layers, tonal adjustments, etc.; then save; then flatten and resize to the print size at 360 dpi; then sharpen; then do a save-as for future prints of that size; then print.



11-Oct-2004, 14:24
I didn't realize that this was the computer forum. There are already lots of them on line.

tim atherton
11-Oct-2004, 16:03
And your point is Bill?

There are no such lists that I know of for LF photographers who have a mixed trad/digital workflow - of which there are many on this list

We even have a "Digital" topic heading.

This is no different from say a detailed thread on enlarger alignment (of which we have had a few I think...) or which contact preinting frame to use

If you aren't interested, then don't read it... simple as that

11-Oct-2004, 20:22
There goes the neighborhood. I have no objection to digital, it's non-specific computer problems that I feel don't belong in a LF forum. Just expressing my opinion, which is surely worth at least a little something.

Paul Kierstead
11-Oct-2004, 21:03
I understand your frustration a little, Bill. I expressly read this forum to avoid all the digital madness, even though I do shoot some digital and print digitally. But I think there is a place for some and perhaps if you have a little patience for it, things can work out. Although not specific to large format, dealing with resolution areas is far from "non-specific computer problems" and extremely relevant to image quality, which many of us care deeply about. Now I will admit such a question could have been asked in any number of photography forums which are more digital oriented; why, you might ask, pollute LF Photography Forum with such stuff?

I can give you my answer why I like to see this question here: Because people here will definitely have a different view on *this* kind of question then many other forums. I have surfed many others where "I get ultra-high quality 20x30's from my 4 megapixel camera" is not only the common opinion, it is the respected opinion. Do you think I trust their opinion on rezz'ing up? I don't; obviously my priorities are quite different then theirs, other wise I would never be shooting 4x5 in order to get 16x20's that I like, I would just shoot a 3 MP digicam.

So, I for one, ask the traditional printers to be patient when quality-related questions come up about the digital darkroom; although the questions could be asked anywhere, the answer *will* vary with where it was asked.

Robert Ludlow
12-Oct-2004, 04:59
Hello. Some of these responses make me feel like I should apologize for intruding into this forum. Actually, the topic started with a question under the title "Epson 9600" in the Digital category. But when it looked as if that thread might have dropped of the radar, I reposted my question in this category, which now appears to have been a mistake. I don't even remember how I found this forum, and since I shoot digital with an 8mp Canon, this does not look like the appropriate forum for my questions. Truth is I don't even remember how I came upon this forum in the first place--I just saw that question, and since it was relevant to my work, I chimed in. Sorry about that--didn't mean to corrupt the neighborhood. :~)

Thanks to Hogarth and Chris for providing helpful information that enables me to move forward with more confidence. Making large prints--for me, that's 24 x 36--from 6 or 8 megapixel digital camera files is very much image dependent, as Hogarth said earlier. I have a few that stand up quite well after much Photoshop massaging. If I were going to try to sell lots of large-format prints, I would get a large-format film camera, but for a variety of reasons I'm not planning to take that step.

Thanks for the hospitality, and in the future I will ask my questions on a more appropriate forum.

12-Oct-2004, 07:31
Hello, Robert. Well, it's a new day and thanks for making me feel like a total jerk which, apparently, I am. Sorry.

Robert Ludlow
12-Oct-2004, 09:33
Hey Bill, no intent to make you or anyone feel bad. I have tremendous admiration for large-format photography, and I certainly understand that it's different from what I do with my 8-megapixel digital camera. For better or for worse, I'm sticking to digital, so I meant it when I said there are more appropriate forums for my questions. Sorry if my reply made you uncomfortable.

By the way, I really like the way this forum is set up.

chris jordan
12-Oct-2004, 10:15
Bill, I don't know what "non-specific computer problems" you are complaining about, but what we're discussing here is the resolution of the Epson 9600, which is a large-format color printer that we use to make prints of our large-format photographs. For those of us who print digitally, this is no different that discussing the optimum aperture of an enlarging lens. Far as I can tell, the only non-specific problem going on here is your random complaints such as "what, huh?", which was your initial contribution to this thread. Maybe in the future if photographers here discuss details of their digital photographic printing practices, you could hold your eloquent tongue and maybe learn something in the process.

Jim Rice
12-Oct-2004, 17:47
I, frankly, don't see the issue with this post being here. The heading clearly defines it as "digital". And once one has the capture, printing questions and the answers to them enlighten those of us, like me, who are contemplating the digital darkroom. I'll be scanning 4x5 Velvias, and maybe 8x10s. The topic interests me.

Brian Kennedy
13-Oct-2004, 12:11
I print with an Epson 4000, and I can clearly see the difference between 300 DPI and 360 DPI. Anyone can see the difference given the right subject matter. According to the thread referred to above (on the Yahoo! Wide Format forum), the Epson 4000/7600/9600 native resolution is 360 DPI. With LF scans, since we're usually down-sampling to the printed resolution, it's important to know that for best quality, you should stick to 360 DPI for the Epson wide format printers. For the Epson 13x19 printers, I have been told that 300 DPI is the native resolution (I can confirm that seems to be correct for the 1270).

In my case, I first noticed the difference when printing pages for a homemade book from my trip to Italy last year. The pages have text and photos on them and are 11x17 in size. I printed the first two-thirds of the book on an Epson 1270 at 300 DPI. When I printed the next page on my 4000, using the same template as the first pages, the text look bad compared to the 1270 prints, not nearly as smooth. At first, I thought, "Gee, the Epson 4000 doesn't even print as well as the 1270." Eventually, I decided to try to reset the whole template to 360 DPI. It made all the difference in the world. The text is smooth again and the pages look exactly the same as the 1270 at 300 DPI.

Like much of what we do, a non-critical eye probably wouldn't notice any quality difference between the 300 DPI and 360 DPI print. However, I think anyone on this forum would easily notice what I noticed. The difference jumped right out at me when I wasn't even looking for it (when I assumed 300 DPI would work just as well on the 4000 as on the 1270).

The difference is not particularly noticeable in photos, but it is clear in the crisp, clean lines of black lettering on a light background. For most applications, I can't tell the difference, so I don't hesitate to print smaller digital files (like from my DSLR) at 240 DPI or 300 DPI if I need to. However, I know now that the printer is up-sizing to 360 DPI.

Ken Lee
13-Oct-2004, 12:56
Brian - Thanks for this info.

The Epson 2200 is not a wide-format printer per se, but it uses Ultrachrome inks, and was released concurrent with the 7600 and 9600. Nevertheless, do you suggest that its native resolution is 300, rather than 360 dpi ?

Ken Lee
13-Oct-2004, 14:26
In the same vein, we read that the Ultrachrome printers deliver output up to 1440 x 2880 . How does this relate to the limit of 360 ppi ? Am I mixing apples and oranges ?

13-Oct-2004, 15:03
I'm trying to answer a lot of these question also (for an epson 1280).

A few things I do know:
the printer's output resolution (780x2880, or whatever) has little to do with the ideal resolution of the art that you send to it. It doesn't work the same way as screen printing, but it's similar in enough to use as a comparison. An image setter might have a resolution of 2400dpi. Because of the way different densities are created within a line screen, however, this resolution needs to be sixteen times the final screen frequency. Which leads to 150 lpi. At this maximum screen frequency, art resolution beyond 300dpi (possibly less) is completely wasted. This is one third the full resolution of the imagesetter.

Similarly (though not exactly for the same reasons) it's ludicrous to send a 2800dpi (at final resolution) file to your epson printer. Never mind the limits of human vision, which is a whole other can of worms. You will be sending gobs of information that the driver will simply discard, and possibly do so in a way that is not friendly to your final output.

The question of what the ideal resolution is for any given driver still remains, and I'm curious to hear it.

Text is a different story. Same with photos that include text layers. This is line art, and as such can use all the resolution you can give it (within the limits of the printer). 2880dpi might not be overkill for text if the paper is smooth enough.

chris jordan
13-Oct-2004, 16:35
Ken, the native resolution of all of the current Epson printers is 360 dpi. A 360 dpi file should always be sent to the printer, so that the printer's driver does not need to interpolate. If you send it a file at any other resolution, including a 720 or 1440 dpi file, it will interpolate it to 360, with a degradation in quality.

Then, it takes each pixel in the 360 dpi file and divides that pixel up into a grid of very fine dots. If you are printing at 720x1440, that means the printer prints a 2x4-dot pattern for each pixel. If you print at 1440 x 2880, it supposedly prints a 4x8 dot pattern, but as far as anyone can tell, there is no visible difference in the print.

So, res your files to 360 dpi before printing. It does not matter whether you have to res up or down; the printer needs a 360 dpi file.


Brian Kennedy
13-Oct-2004, 22:25
Ken - I don't doubt Chris is correct about the 2200. I am basing the 300 DPI note on what someone else said to me in another Internet forum. With my old 1270, there is no clear increase in print quality with 300 DPI versus 360 DPI, but with the 4000, I noticed the difference right away. Maybe the 1270 is better at interpolating, maybe it has smaller droplets, or maybe it's a function of the 1270 dye inks versus the 4000 UC inks. I was told (on the other forum) that the reason was because on the 13x19 printers, the sweet spot was 300 DPI rather than 360 -- hence my note above. I agree it would make more sense if it were 360 DPI for all of the printers, at least for all of the UC printers.

It would be interesting to pull up that Yahoo! Wide Format Group thread again, because I could swear that there was a note from someone who seemed very knowledgeable stating there was a certain paper type where the Epsons interpolate to a 720 DPI image when you select 2880 in the print driver (I want to say it was with Premium Glossy, but it escapes me), and that otherwise the native resolution is 360 DPI for all papers.

michael barnett
30-Oct-2004, 13:07
Am I missing something? I see time and again persons dicussing the relationship of file resolution to printer resolution in DPI (dot per inch) for both situations. I thought file resolution is mearsured in PPI (pixels per inch). Can someone set me straight?

Larry Gebhardt
30-Oct-2004, 15:12
Michael, nothing is official. It cuts down on confusion if you use PPI for images, but DPI is well entrenched among users, so you just need to infer what is intended by the context. I guess you can think of either dpi or ppi for images, but only dpi for inkjet printers.

Don Miller
30-Oct-2004, 17:21
I see that Mike Chaney (author of Qimage) says that the Epson driver operates at 720 ppi:

http://www.ddisoftware.com/qimage/quality/#quality (http://www.ddisoftware.com/qimage/quality/#quality)

I've been using 360 ppi as many other people have. But Mike is the smartest guy on earth (TM) when it comes to this stuff, so I'm switching to 720 ppi. If mike is wrong then we're at "the end of time" so there's no risk in switching.

I'm not being sarcastic, if Mike says it's 720 ppi it's 720 ppi. That'll be about a 1 gig print file for 24x30 at 16 bits. (and your wife said that old computer would do...HA)

Ken Lee
30-Oct-2004, 18:36
Don -

Thanks for the wonderful link.

Note that the author provides two images with which you can test the resolution of your Epson or Canon printer... now we're talking !

Concerning Qimage, is it used primarily for printing ? In other words, one uses a Photo Editor to perform corrections, etc., - and then uses this to print ? In my workflow, I always use PSD files, since they use a lossless compression algorithm and are native to Photoshop. I'm puzzled about how this would all work together. Any insights would be most welcome !

Don Miller
30-Oct-2004, 20:06
Ken, yes most people use Qimage as the printing program after photoshop edits for efficiently placing multiple images on a large sheet or roll. It will print psd files. It doesn't have its own file type doesn't normally change the photoshop file. Look at the Qimage web site for the many more features Mike has added since the program's beginning.

This program may not be worth purchasing for an LF photog who usually prints one at a time. For printing a large number of images it is indispensable. It's $45 and there is a free trail. With this program, it is well worth going through the tutorial first. I didn't and was frustrated.

Note that in his quality comparison he is using photoshop 6.

An interesting statement Mike makes at the top of the linked document is that the 720 ppi number is less important for files that are upsized. With our LF images and newer scanners we don't usually need to upsize. I've been doing a lot of looking at resolution from the Canon 9950f scanner so I'm curious to examine prints from a 720ppi scan.

Ken Lee
30-Oct-2004, 20:27
"An interesting statement Mike makes at the top of the linked document is that the 720 ppi number is less important for files that are upsized."

Yes, since one of the advantages he offers, is his algorithm for downsizing: Throwing out the right pixels, in the right manner, to avoid introducing artifacts, like jagged lines, noise, etc. When I get back to my "digital darkroom", I intend to try printing his test files on my Epson 2200, and I intend to observe the difference between what Qimage delivers, and what Photoshop CS delivers.

Thanks again. It's postings like this, which help keep some of us large format photographers on track, towards making more beautiful images, as beautiful as the lastest technology allows.

Leigh Perry
1-Nov-2004, 04:28
> This program may not be worth purchasing for an LF photog who usually prints one at a time. For printing a large number of images it is indispensable.

QImage has another major advantage. It manages memory beautifully. I usually only print one at a time, but I print it using QImage. Photoshop printing used to fail after about 25 inches of roll paper (an expensive failure) due to memory issues. QImage suffers no such problems. It memorises your printer driver settings too, which is a great feature.

Be warned though: the user interface is sincerely twisted. If you are using it to lay out tiled images, you have to be prepared to accept what QImage wants to do with them, otherwise it's an exercise in frustration. But for straightforward handling of nerve-wrackingly large prints, it is great.