R2400 resolution

In Eric Chan's excellent article this month he states the native resolution for the R2400 is 720. I was under the impression it was 360, but after looking in my manual I can't seem to find either figure.

Can someone confirm that it is indeed 720? I've always set my resolution in PS at 360 and have gotten good results. Do I need to change?

Bill, most Epsons indeed have a native max resolution of 720 dpi in the print driver. If you've been using 360 that's probably not a bad thing. In many cases, you may not notice any difference interpolating up to 720 dpi. However it is often possible to see some difference in areas of the image that possess fine detail. I habitually use 720 dpi myself -- printing via Qimage takes care of all this interpolation stuff fairly automatically.

The print driver resolution is a different matter than the actual printing resolution based on the head design, which is usually much higher and measures ink droplets rather than RGB pixels. But the most that the driver will take is 720 dpi. Whatever you give it, it resizes from there to lay ink on paper.

Note that printer driver settings can change the printing resolution. There are 4 print quality levels in the 2400's driver, which I believe correspond simplistically as follows:

• - Fine: 360 dpi
  - Photo: 720 dpi
  - Best Photo: 1440 dpi
  - Photo RPM: 5760x1440 dpi (this one is more complicated)

None of these at all effect the resolution of the image data that the driver will take from you, however, which remains fixed at a maximum of 720 dpi. So don't get the two mixed up. (In fact, to avoid confusion some people will specifically use PPI -- pixels per inch -- to describe the image file resolution, and DPI -- dots per inch -- to describe printing resolution.) I typically leave my 2400 driver set on Best Photo. Tests I've done or seen show no real benefit in using the higher print res of Photo RPM.

Back to 360 vs. 720 dpi interpolation, my best advice is... try it on some of your images and see the if the results matter for you. Looking over this page from the author of Qimage may give you some food for thought as well:
http://www.ddisoftware.com/qimage/quality/

Thanks Royce. I can't believe I've had it set incorrectly all this time! I think I will leave my exisiting images as is, as I've never had a complaint about the details, sharpness, etc., but will change the default resolution in CS3 to 720. Thanks again!

Don't think of 360 as being incorrect, more a small degree of fine tuning and personal preference. I'm guessing some people will respond here saying they never use 720 dpi and like it that way just fine. The fact that you've received no complaints about your prints tells you that we're talking about a potential improvement up in the top few percentile. I'm sure Eric will chime in shortly too on his experience.

If you try going to 720, you may or may not readily see a difference on any given print. But it's a thing mainly important to people with a conscious eye for detail (which of course describes many of us photographers ). I'm guessing that many of your print viewers / customers will not think to notice a difference unless you were to put versions of the same print side-by-side and then point out the little details.

Factor in the nature of your images, print size and media too. Fine detail is probably more a concern on high contrast, high res B&W images printed on glossy stock than for pastoral color scenes printed on matte fine art paper, for example.

Note to others reading this... the 360 vs. 720 dpi point relates to Epson printers. For Canon and HP printers it is typically a 300 vs. 600 dpi choice, but the same principle applies.

I'll chime in, but only to say that Royce already said it all.

The main point that I'll emphasize is to try some of your images with finer detail at both 360 ppi and 720 ppi and see if you can tell the difference. If not, then stick with 360 ppi simply because it will lead to smaller file sizes and faster spool times.

Regarding the actual printing resolution, remember that the high numbers such as 1440 dpi refer to individual droplets of ink, where an ink is of a single color (e.g., one droplet of Magenta, one droplet of Light Black, one droplet of Yellow, etc.). As Royce noted, it takes many droplets (drops of different colors mixed together) to form a single pixel. Exactly how this is done is handled automatically by the driver using some secret sauce.

Thanks Eric. Great article BTW.

What might be a problem with setting a 720 resolution is sharpening. Allready at 360 the image will be quite much bigger on screen than on paper. If you are not able to fine tune sharpening at 720, then interpolating the image up to this resolution might give you no real benefits. The fine detail in an image needs perfect sharpening to look good on paper.

Yes, that is a point. Proper interpolation and output sharpening techniques go hand in hand, IMO. Doing one without the other is a partial measure. Again, this is why I use Qimage because it encapsulates a single output processing mechanism that handles both interpolation and sharpening at the final upsized resolution.

Of course there are other workflows & tools that apply to this including the 3 stage sharpening technique written by Bruce Fraser, Jeff Schewe, et al, as well as their tool PhotoKit Sharpener...

Hi guys, I've run a couple of tests and didn't notice enough difference to make it worth the huge difference in file size. Most of my images are already 50-80MB's, and at 720 they went out of the roof in size! I use PK sharpener and have always gotten excellent results, even with large prints sizes from my D2x. Thanks for all your info and help.

There you go, Bill. Sounds like 360 is the right res for your purposes. Print away & enjoy!