Longshadow Loc: Audubon, PA, United States

Oh, okay, square dots.
But ink (printer) dots are round, right?

CHG_CANON Loc: the Windy City

Every question was asked specifically to illuminate the fact that DPI has nothing to do with pixel-based images, not when viewed, nor when printed, not when created by cropped cameras, not when created by full-frame, nor other formats.

When I display the attached 1920-wide image on my 1920-pixel screen, I'm see exactly 1 pixel in the image as 1 pixel on the screen. Consider these questions:

Q1 The image was captured on film, does that explain why it as a DPI = 1 if you download and check the file properties?

Q2 If this monitor is 81 ppi and and the image is 1920x1080 pixels, will it look the same printed as it looks on my (or yours, anyone's) screen?

Q3 Can the image be printed to 300 DPI if the file reports DPI = 1?

Q4 It seems like 300 ppi would give about a 6x4-inch print? But, this "full HD" monitor is roughly 20x14-inch. If printed at 81ppi to 20x14in, will the print be WYSIWYG - What You See Is What You Get?

(Download)

BebuLamar

I wouldn't know how your image reports dpi. But each pixel on the monitor is formed by 2 dots a R, A G and a B dot of different intensity.
On an inkjet printer a pixel is made up of many dots and each dot can only have the color of one of the inks you have. If you have 4 ink printer each of the dot is only either Y, C, M or black and the dots can't vary the intensity so it takes good number of dots to simulate the color of a pixel.

TriX Loc: Raleigh, NC

There are no “dots” on a modern LCD display, there are pixels. In the old CRT days, when there was a physical mask between the electron guns and the phosphors on the screen, the size of the holes in the mask were referred to as “dot pitch”, with a smaller number such as .24 indicating a higher resolution display than a large number such as .38. But even then, it was a misnomer as the mask in Sony Trinitons had square, not round holes. Now there are no masks, no electron guns and no “dots” - there are pixels in an x-y display, and we refer to the resolution of the display as x pixels x y pixels. Some manufacturers do quote PPI, but never DPI as this is a printing, not a display term (as Paul has been saying for 4 pages).

bleirer

Just trying to point out a possible fault in the OP theory.

BebuLamar

The dots are actually rectangular but the 3 dots make up a square pixel on the screen.

BebuLamar

There are 3 rectangular LCD elements for each of the pixel on an LCD screen. One LCD element can only have one color red, green or blue.

TriX Loc: Raleigh, NC

No argument with that.

Longshadow Loc: Audubon, PA, United States

Longshadow Loc: Audubon, PA, United States

Left-right? up-down?
Which are the R, G, & B?

CHG_CANON Loc: the Windy City

Is it one angel of each color in a pixel, or can I go 4 red angels for every green replacement?

BebuLamar

left right. 3 rectangle LCD element of 1 wide by 3 high in order of left to right R, G and B. That's most of the LCD monitor. Of course some manufacturers may want to arrange them differently.

TriX Loc: Raleigh, NC

It’s preordained - one red angel, one blue angel and two green angels... (for each pinhead - oops, I meant pixel) 😇

a6k Loc: Detroit & Sanibel

🙉

blackest Loc: Ireland

What can you resolve? for an 8 by 10 print 300dpi is fine at a normal viewing distance some where it was figured 10 line pairs per mm is pretty much as detailed as you need to be to not be able to resolve the lines with 25.4mm to the inch that corresponds with 254 lines per inch so 300 dpi is overkill really If you want a bigger print you can use a lower dpi as you view it from further back.

Cropping you can get a pretty good idea of crop factor dividing your image into 3rds and 1/4s if we start with 1/4s each 1/4 represents a 2x crop factor if the lens was a 50mm then 1/4 of the frame is a 2x crop or 100mm field of view if you divide into 1/3rds horizontally and vertically and use 4 of those thirds you have a 1.5 crop and that part of the image from a 50mm lens has a 75mm field of view if you take a single third thats a 3x crop and you are now looking at a 150mm field of view from that 50mm lens. depending on the sensor that 1/3rd section is probably too much to crop to.
An 8x 12" at 300 dpi is roughly 8.6Mpix and for my 36mpix camera the most i would want to crop is 2x if i wanted a reasonable IQ if I don't crop at all i'm looking at about 600dpi and at a normal viewing distance for an 8 by 12 i wouldn't resolve the image any better than the 300 dpi image.

To be fair this is of more use in the field, if the bit you are interested in is only a 1/9th of the frame you really want to swop to a lens 3x longer a 1/4 2x longer or 4/9ths 1.5x longer these longer lenses will be designed to perform at these distances. I hope this is useful. To be fair if you are going to crop into your image you need to raise your shutter speed by a stop or more too.