Is there a native print resolution?
Hi,
We know that for an LCD display there is a native resolution that will display images and text at the best possible sharpness and clarity. That is, if we had a 1024x768 LCD display, the best signal input signal to drive it with, is exactly that, otherwise we will get blurry images. My question is, whether there is a similar thing for printers and CRT displays?
For example, a 1440 dpi printer would be capable of spraying 1440 print dots per inch. If we were to send a 300 ppi image to the printer, we would be using 4.8 print dots per pixel. If we were to send a 240 ppi image, we would be using 6 print dots per pixel.
My intuition tells me that if we were to use an integer multiple of print dots per pixel, our image would be theoretically sharper as there is no interpolation. Is that correct? If what I said about the integer multiple thing is correct, printing at say 241 ppi (5.9751 dots per pixel) would be LESS sharp than printing at say 240 ppi (6 dots per pixel) on a 1440 dpi printer. Right? Chances are, we can't tell the difference anyway, but is there a THEORETICAL difference?
Should I aim for an integer division of my printer capability (for photos)? Sometimes when you crop photos without resampling, you can get odd resolutions (ie 257 dpi, 216 dpi, etc...)
What about CRT displays? Surely there is a finite resolution dictated by the grill size.
Confused...
EDIT : Accidentally hit enter before I could complete the title. Should read "Is there a native print resolution?". Mods can you change it please? Sorry about that.
[Edit by Amorph: Fixed thread title as requested.]
We know that for an LCD display there is a native resolution that will display images and text at the best possible sharpness and clarity. That is, if we had a 1024x768 LCD display, the best signal input signal to drive it with, is exactly that, otherwise we will get blurry images. My question is, whether there is a similar thing for printers and CRT displays?
For example, a 1440 dpi printer would be capable of spraying 1440 print dots per inch. If we were to send a 300 ppi image to the printer, we would be using 4.8 print dots per pixel. If we were to send a 240 ppi image, we would be using 6 print dots per pixel.
My intuition tells me that if we were to use an integer multiple of print dots per pixel, our image would be theoretically sharper as there is no interpolation. Is that correct? If what I said about the integer multiple thing is correct, printing at say 241 ppi (5.9751 dots per pixel) would be LESS sharp than printing at say 240 ppi (6 dots per pixel) on a 1440 dpi printer. Right? Chances are, we can't tell the difference anyway, but is there a THEORETICAL difference?
Should I aim for an integer division of my printer capability (for photos)? Sometimes when you crop photos without resampling, you can get odd resolutions (ie 257 dpi, 216 dpi, etc...)
What about CRT displays? Surely there is a finite resolution dictated by the grill size.
Confused...
EDIT : Accidentally hit enter before I could complete the title. Should read "Is there a native print resolution?". Mods can you change it please? Sorry about that.
[Edit by Amorph: Fixed thread title as requested.]
Comments
Same goes for a 1440 dpi print, although ink jet resolution is something of an inflated metric.
The take home message is that, since the image goes through a number of transformations from screen to page, you want the source image to have as high resolution as feasible (usually 300dpi is plenty), and it doesn't matter that the printer output resolution is not a clean multiple.
Originally posted by Splinemodel
and it doesn't matter that the printer output resolution is not a clean multiple.
That's what I was hoping for, makes life easier. But I still don't understand why. From what I understand, most inkjet printers spray fixed sized dots and the apparent color we observe is due to how close the dots are. That is, lots of dots close together equals more saturation. Finite dots are used to produce the color, hence, we should have a relation between the number of dots used to represent each source pixel. ???
What about CRT displays? Surely such a problem exists as well.
The best explanation I can think of is that the size of the dots (in printers and CRTs) are so small that it makes no difference whether an integer multiple or not represents one source pixel for practical purposes, but there is still a theoretical difference. Furthermore, at that fine resolution, other effects like ink absorption in paper or energy spreading in the phosphors dominate.
Originally posted by drumsticks
Thanks for changing the thread title. Sorry about that...
That's what I was hoping for, makes life easier. But I still don't understand why.
The dots from an inkjet are:
1) circles, not squares
2) put down according to special algorithms
Changing the source resolution just changes the way the circular dots are patterened, combined, and overlapped.
For a CRT, the pixels are also circular. A shadow mask or an aperture grille turns the circles into squares.
Originally posted by Splinemodel
The dots from an inkjet are:
1) circles, not squares
2) put down according to special algorithms
Changing the source resolution just changes the way the circular dots are patterened, combined, and overlapped.
For a CRT, the pixels are also circular. A shadow mask or an aperture grille turns the circles into squares.
I see... Thanks a lot
Originally posted by Splinemodel
For a CRT, the pixels are also circular. A shadow mask or an aperture grille turns the circles into squares.
CRTs do not display pixels as squares.
Actually, the representation of the pixel as a square is an abstraction (for our benefit) as seen in a graphics application when zoomed in close. In print, LCD, Plasma or CRT, the actual representation of that pixel is executed in very different ways.
In displays it is often an arrangement of a triad of red, green and blue light, but the arrangement differs radically...
http://www.necmitsubishi.com/support...crt_theory.htm
A pixel is an arbitrary measurement, both the size of the pixel and it's aspect ratio or shape and position relative to its neighbors can be nearly anything.
The ultimate execution of that information is entirely up in the air, be it print or screen or projection.
(Projectors are even stranger up close, some involving arrays of little pivoting mirrors)...
When you look at a zoomed-in pixel in Photoshop that is just a nice, easy-to-understand representation of the desired color - not the actual thing you'll see in the final version.
I believe only OLED displays do actually have a single, square pixel not composed of triad subpixels...so in that one case the pixel as seen in zoomed view might be similar to the real thing being displayed. (Maybe other types of displays also had this, but not that I know of).
But typically the square pixel seen in Photoshop is not "the actual thing" anymore than your folders on your Mac are actual folders. (Hint: Folders are just files too).
It helps to stop thinking of the pixel as a square of a certain color but more the on/off switch that it actually is. All you are telling the display (via setting a color value for that pixel in the file) is blink your r,g,b, sub pixels in this combination and intensity (and in the case of video) for n length of time, (or not at all, in the case of black).
The square, single-color pixel is shown to you in photoshop as such because there is no need to mire you in the details of implementation (that it'll be broken into r,g,b subpixels or c,m,y,k dots, for example) for any number of display types/printer types. The pixel you set to be a certain color is a suggestion. The receiving device does it's best to honor it (often needing to approximate).
We can, of course, all happily believe the well-intentioned lie of the square single color pixel, that's the point of graphical computing - ease-of-use.
Just like we know a dollar is a hundred pennies, or 10 dimes, or 20 nickels or myriad combinations thereof...
We want to express a color merely as a color, not some unintuitive combination of flashing 3 colors at varying degrees of brightness or overlapping of ink dots.
Originally posted by johnq
Actually, the representation of the pixel as a square is an abstraction (for our benefit) as seen in a graphics application when zoomed in close. In print, LCD, Plasma or CRT, the actual representation of that pixel is executed in very different ways.
It helps to stop thinking of the pixel as a square of a certain color but more the on/off switch that it actually is. All you are telling the display (via setting a color value for that pixel in the file) is blink your r,g,b, sub pixels in this combination and intensity (and in the case of video) for n length of time, (or not at all, in the case of black).
Almost like the Alexandrian solution to the Gordion knot problem!
Originally posted by drumsticks
Wow, thank johnq. That's got to be the best explanation ever. I'll save it for future reference
Almost like the Alexandrian solution to the Gordion knot problem!
Took me a while to figure out what the Gordian Knot was.
Originally posted by Whisper
Took me a while to figure out what the Gordian Knot was.
As it should be
Took me a minute to remember what a voxel is...
Originally posted by johnq
As it should be
Took me a minute to remember what a voxel is...
I remember my foggy "not quite right" definition of a voxel, but I don't think I've ever been particularly clear on what a voxel is.
Originally posted by Whisper
Took me a while to figure out what the Gordian Knot was.
Love the graphic!
Originally posted by drumsticks
Love the graphic!
Did you go to the site I got it from? It would seem that someone really has found a way to tie a knot that cannot be untied.