Problem printing A2 @ 1440ppi on Epson SC-P900

[Hans Von Bongo Papster]

I am having an issue printing to A2 on my Epson SC-P900 with a resolution of 1440ppi.

After pressing Print, the photo appears to be sent to the printer but the printer doesn'r receive it. After a while an error message appears.

If I drop the resolution to 720 ppi it works so the problem is the spooling to the printer.

Lightroom Classic 13.1

Mac Studio M1 Max; Sonoma 14.2.1; 64Gb RAM; 1TB SSD (500GB available)

[JohanElzenga]

You should not try to print at 1440 ppi. This may be the hardware resolution of the printer, but the printer needs to use multiple droplets of ink to print a single pixel, so the resolution of the image sent to the printer must be much lower. Even 720 ppi is still overkill, 360 ppi is more than enough. You also will not have enough pixels to print an A2 size print at 1440 pixels. A2 paper is 16.5 x 23.4 inches. To make a print this size at 1440 pixels per inch, you need 16.5 x 1440 x 23.4 x 1440 pixels = 800,616,960 pixels. That's 800 Mpixel...

[Hans Von Bongo Papster]

Cheers Johan, you are of course right 720 is quite enough!

[JohanElzenga]

Cheers Johan, you are of course right 720 is quite enough!

By @Hans Von Bongo Papster

Like I said, even 720 ppi is too high, and probably way more than the number of pixels in your image. You would need an image of 23.4 x 720 pixels = 16,848 pixels wide and 16.5 x 720 pixels = 11,880 pixels high. That's still 200 Mpixel! Use 360 ppi. 

[Hans Von Bongo Papster]

Ok. Are their any papers which benifit from the higher resolutions or is the result more or less the same on Glossy. Semi-gloss, Fine Art, etc?

[Conrad_C]

Just to be clear, there are four different potential resolutions that every print job deals with. In short (referring to the picture below), for A you either leave it blank or enter up to but no more than 360 ppi, and for the option marked B you will typically choose 720, 1440, or 2880 ppi.

If you want more details about the four resolutions I’m talking about…

Effective image resolution. If for example your image is 6000 x 4000 px (24 megapixels), at A3 size (11.7 inches wide), that image is 6000 pixels divided by 11.7 inches or 512.8 pixels per inch (ppi). In Lightroom Classic you usually don’t have to think about this number, but this is the starting resolution: Image pixels divided by a physical dimension.

Lightroom Classic print resolution. This is the resolution of the data Lightroom Classic sends to the printer driver software, marked in the picture below as A. You can leave this blank, and Lightroom Classic will send the data without resampling* (I assume that’s the effective image resolution). If you choose to enter a number here, for an Epson printer you should enter no more than 360 ppi.

Printer driver data resolution. This is the resolution of the data that the Epson printer driver sends to the printer hardware after receiving it from Lightroom. Here, it is totally OK to specify 720, 1440, or 2880 ppi, because this is the data resolution after the Epson printer driver software has converted the RGB colors from Lightroom Classic to the many ink colors in the Epson printer. In the picture below, this is marked B.

Printer hardware resolution. Looks like the P900 print heads can do 5760 x 1440 ppi, according to the spec sheet. The short dimension (1440 ppi) is the print head, the resolution is higher (5760 ppi) along the long dimension because the printer can vary the stepper motor to position the print head more precisely than the actual nozzle spacing. You don’t need to think about this resolution because the printer driver handles mapping the color values to the ink dot screening pattern.

*This is according to the book Lightroom Classic: The Missing FAQ by Victoria Bampton, who in turn credits photography and printing expert Jeff Schewe with the research.

[Hans Von Bongo Papster]

Thanks Conrad,

Same question as to Johan... is their any paper type which benefts from higher print resolutions? 

Alistair

[Conrad_C]

It’s a very good question. Generally, how I understand it is that it is not just about the paper type, it’s affected by quality control along the entire image processing chain. When setting Output Resolution in the Epson printer driver, generally:

720–1440 dpi. Should look OK with average images on most papers, especially matte. Canvas could go down to 720 dpi. This has to do with how much resolution the media can actually hold; for example canvas is so rough you won’t be able to see the difference between 720 dpi and higher settings.

1440–2880 dpi. 1440 is usually OK for almost everything. 2880 dpi can potentially reproduce more detail and sharpness, but this depends on two things: The quality of the image, and the quality of the media. The image must be captured with a sharp lens, with perfect focus, no motion blur, and enough of the original pixel dimensions (for example, if you crop or enlarge too much there might not be enough pixels in the print area to reproduce 2880 dpi at the final print size). The image must be processed in a way that properly preserves original detail (e.g., not overdoing noise reduction) and not going too far (over-sharpening until there are visible halos). And the media must be at the high end of the scale for reproducing detail, such as Epson Ultrasmooth matte or one of the more expensive glossy papers. Less smooth papers, such as those with Rough, Textured, Velvet, or Watercolor in the paper name, may not reproduce much additional detail over 1440 dpi.

If you want to keep it simple (this is what I do, since I don’t have the very best equipment), just leave Resolution blank in Lightroom Classic, the Epson driver set to 1440 dpi, and the High Speed option enabled, unless it’s a special image on high quality media and then you can set the Epson driver to 2880. You can run your own tests to find out if you can see any difference with your images and papers on 1440 vs 2880; if not, leave it on 1440 dpi.

There is even more to print quality than just those factors; for example disabling High Speed means the print head will lay down ink unidirectionally (slower) instead of bidirectionally; on the old Epson printers that could potentially improve print quality a slight bit more but some say High Speed is just fine today. Also, there are debates on the web about whether the Finest Detail option makes a difference for photos (some say it is only for graphics such as vector art).

Part of my understanding comes from the heading “Printer-Specific Settings” starting on page 181 of the book The Digital Print by Jeff Schewe. (His book makes a case for Finest Detail making a difference with photos, but again only if the image resolution, image quality, and media are high enough quality to support what it does, and only if High Speed is disabled.)

[JohanElzenga]

For anyone who reads this and is still confused: If you look at this screenshot, then you'll notice that the printer driver Output Resolution (B) is specified in dpi (dots per inch), not ppi (pixels per inch). That is not a mistake or sloppiness, that is the fundamental difference between these two. For an inkjet printer you could say that dpi stands for 'droplets per inch'. The output resolution defines how many ink droplets are used per inch. Because one color pixel is built up by multiple droplets, the output resolution in dpi is always much higher than the required image resolution in pixels per inch. So for best print quality do use 1440 dpi output resolution, but that does not mean that the print resolution (A) must be 1440 ppi in that case. A print resolution of 360 pixels per inch is plenty. The standard print resolution has been 300 ppi for ages, but for technical reasons 360 ppi is slightly better on Epson printers because 1440 is exactly 4x 360, meaning the printer can use 4x4 dots/droplets per pixel. Why is this plenty? Because the human eye is incapable of seeing finer detail at the distance you view the print. And because a higher print resolution would mean fewer dots/droplets per pixel, so it could theoretically even make the print quality worse.