Correct Print Resolution for Epson Printers

[digitaldog]

Jeff, in the article does misuse dpi when he says, “... Epson pro printers’ print heads have a reported output resolution of 360/720 dpi...”. The 360/760 is an expected input resolution (ppi) that the printer expects to get.  If it gets a different number it (either in driver or printer software) will interpolate to the number.

If one reads (carefully) Jeff's article, when he uses DPI, it refers to prints, and where he refers to PPI, images. For example:

So, an image that’s 5616×3744 pixels can have a dimension of 23.4×15.6 inches when set to a pixel-per-inch (ppi) of 240. If you set the resolution to 360 ppi, the print dimensions are reduced to 15.6×10.4 inches.

And then:

No, but the print made at 360 ppi will have better image quality and finer detail.

Made from an image with that PPI.

Lastly, I think the statement would be “even encoding 8 bit, two different numbers can be perceived as the same color”

Yup, because color IS a perceptual property of (in this discussion) humans. So if you can't see it it's not a color. Color is not a particular wavelength of light. It is a cognitive perception, the excitation of photoreceptors followed by retinal processing and ending in the our visual cortex, within our brains. As such, colors are defined based on perceptual experiments. In ProPhoto RGB, G255/R0/B0 is not a color. It is a device value.

Two numbers that produce the same color appearance (and we can measure and define this difference precisely) IS the same color no matter the encoding:

[bjanes]

In terms of Jeffs article, one can use PPI and DPI interchangeably: image pixels are used to create dots.
What makes you believe that an ink jet print can't be considered continuous tone? Under a strong enough magnifier, what is? Certainly not a display who's output resolution can be lower than some digital prints.Lastly, even encoding 8 bits, two different numbers can result in the same color.

Please read the cited article by Fraser et al.

"... the practice of using the terms 'dpi' (dots per inch) and 'ppi' (pixels per inch) interchangeably inevitably leads to confusion, because dots and pixels are distinct entities with different properties."

"But most digital hard-copy output devices are not continuous tone. Instead of pixels, they print dots of ink or toner"

The output of a high quality inkjet may appear continuous, but if you look at the print under a microscope you see innumerable randomly spaced color dots. With the output of a true contone device you would see individual pixels. I think the Lightjet430 is a true contone printer (see here).

Bill

[digitaldog]

Please read the cited article by Fraser et al.
"... the practice of using the terms 'dpi' (dots per inch) and 'ppi' (pixels per inch) interchangeably inevitably leads to confusion, because dots and pixels are distinct entities with different properties."

I've got signed copies of all of Fraser's books, he of course isn't wrong, nor is Jeff. Jeff clearly differentiates PPI from DPI in the article when speaking of images composed of pixels and devices that produce dots (in this case, printers). If you or others are confused, I'm sorry. 

The output of a high quality inkjet may appear continuous

Of course it can and thus, how is it NOT continuous tone?

but if you look at the print under a microscope you see innumerable randomly spaced color dots.

And when I examine a silver print with a microscope, I see grain. So what? BOTH appear without as continuous tone. My B&W laser printer of a photo without a microscope, no, it does not.
You stated: "A continuous-tone device such as a monitor ...." Really, even when examined with a microscope? Please explain how a display IS continuous-tone but an ink jet without either being examined with a microscope isn't continuous-tone. Because if the topic is confusion, you've confused me..... 

[digitaldog]

Epson's REPORTED output resolution is:

[JRSmit]

How can a c-print system like lightjet be continuous, as the input is a discrete set of pixels. Furthermore it uses silverhalide paper, which by its very nature is not continuous tone.
A display is a discrete set of pixels, but these pixels can vary in intensity and color. That in itself can be identified as continuous. But the display as a set of pixels in my view can not be called continuous, as i see a grid of pixels.
Not suprisingly as the DPI values of displays are quite low.
.

[bjanes]

I've got signed copies of all of Fraser's books, he of course isn't wrong, nor is Jeff. Jeff clearly differentiates PPI from DPI in the article when speaking of images composed of pixels and devices that produce dots (in this case, printers). If you or others are confused, I'm sorry.  Of course it can and thus, how is it NOT continuous tone? And when I examine a silver print with a microscope, I see grain. So what? BOTH appear without as continuous tone. My B&W laser printer of a photo without a microscope, no, it does not.
You stated: "A continuous-tone device such as a monitor ...." Really, even when examined with a microscope? Please explain how a display IS continuous-tone but an ink jet without either being examined with a microscope isn't continuous-tone. Because if the topic is confusion, you've confused me..... 

Again, re-read Fraser et al:

"But most digital hard-copy output devices are not continuous tone. Instead of pixels, they print dots of ink or toner"--that includes inkjet printers.

"A monitor is an example of a continuous-tone device."

You don't appear to understand the theoretical difference between contone and dithered output.

Bill

[digitaldog]

"A monitor is an example of a continuous-tone device."
You don't appear to understand the theoretical difference between contone and dithered output.

You don't appear to be able to explain yourself.

[bjanes]

You don't appear to be able to explain yourself.

Not to someone with limited comprehension. 

[digitaldog]

Not to someone with limited comprehension. 

Not to anyone here.
Who to believe, you with your inability to explain you opinions or Schewe? 

It seems to me that much confusion in this discussion is failure to distinguish between dots and pixels.

I accept your confusion.

[bjanes]

Epson's REPORTED output resolution is:

Thanks for posting this information. An example may help to explain the difference between PPI and DPI when printing.

Here is the Quality Option dialog for the 3880 printer. For optimum output, one would usually use 2880x1440 dpi. You can set the resolution to anything you want, but for the 3880 the usual values are 360 and 720 as Schewe explains. Here it is set to 720.

Now you have to set PPI sent to the printer. The example shows a D850 image cropped to a 4:5 ratio using Photoshop. When cropped to 8 * 10 inches, the image resolution is 688 PPI. According to Jeff's recommendations one would resample to 720 ppi and send this to the printer, which would use 2880x1440 dpi. If we want a 24 x 30 inch print, the resolution would be 229 ppi. You would sent 360 ppi to the printer. Any more would simple be empty magnification.

[bjanes]

Not to anyone here.
Who to believe, you with your inability to explain you opinions or Schewe? 
I accept your confusion.

As I remember from many years ago with regard as to whether or not a raw file has a color space, you never admit you are wrong and persist in specious arguments until your own referee, Thomas Knoll, clarified the issue. Do you remember this? I'm done here.

Bill

[jrsforums]

As I remember from many years ago with regard as to whether or not a raw file has a color space, you never admit you are wrong and persist in specious arguments until your own referee, Thomas Knoll, clarified the issue. Do you remember this? I'm done here.

Bill

Thanks, Bill  +1

[digitaldog]

As I remember from many years ago with regard as to whether or not a raw file has a color space, you never admit you are wrong and persist in specious arguments until your own referee, Thomas Knoll, clarified the issue. Do you remember this? I'm done here.

Bill

Remember what? Raw does have a color space, it's not a colorimetric color space. I quoted Thomas and others about this as well.
You're done, but can't answer the questions asked of you to explain your opinion. Fine.

[digitaldog]

Since you seem to want to reference Fraser and the color space of raw, do turn to page 375 of the book you referenced:

"Raw files from digital color filter array cameras are linear gamma grayscale images that require processing by a raw converter (such as Adobe Camera Raw) to produce a color image".

So based on your reading of that text, what is the color space of that linear gamma grayscale data?