4 ms·

If I understand this right, * DPI is print resolution, a property of prints and displays * PPI is image resolution, a property of printed and displayed ima

by sesqu 16y ago

If I understand this right, * DPI is print resolution, a property of prints and displays * PPI is image resolution, a property of printed and displayed images * LPI is halftone minimum printing resolution, a property of printers Those are absolutely not the same. DPI is looking at what you got; PPI is looking at what you wanted. LPI, then, is looking at what you can do, and each is measuring a different technological solution to "image". PPI is taking a digital image and saying "I want it yay big", LPI is saying "I'll do it by drawing at least this many differently sized dots of entirely different colors", and DPI is going "This is how many dots I'm counting you did it with". edit: Apparently, some manufacturers of small LED displays like to report DPI as the number of LEDs per inch - that is, 3x the native resolution for images. That's a good example for people like me, who know little about printers.

bonaldi 16y ago
No, DPI and PPI are literally the same thing. (Photoshop used to call what is now PPI "DPI"). "PPI" comes from people wanting a way to talk about the dpi of a digital image without including all the baggage and confusion of dpi, which too few people understand. There's no technical difference, however.
- sesqu 16y ago
  If they're the same thing, which thing is it? The number of pixels (virtual representations; samples) per inch of display, or the number of dots (physical representations; approximate components) per inch of display?
  - bonaldi 16y ago
    You've got a false distinction there. It's the number of constituents that can be packed in per inch: whether those constituents are print dots, physical pixels, or utterly notional (as in displayed images).
    - sesqu 16y ago
      No, that's just the per inch part. I still need to know what the constituents being measured are, as logical pixel vs. physical dot makes all the difference: I don't care about the dot density, as long as there are enough of them; I care about the dots/pixel, and deeply about the actual inches. I ran into this problem as a kid, printing some images that had dpi metadata that the printer took literally, but I didn't know how to fix it back then so I ended up with a thumbnail print. Attaching ppi (!) metadata to images is stupid anyway, since the actually relevant information would be the inches (or the dots/inches, for designer decrees).
      - deleted 16y ago
        [deleted]
      - bonaldi 16y ago
        "I care about the dots/pixel" Yes, but those are two different dots you're talking about. What you actually care about is how many printer dots you get for each image pixel. There is a distinction, and I'm all for precision in language, but it's nothing more than a language distinction for the sake of clarity. It is not a technical distinction, is my point, and people like Bray aren't wrong to call this a 300dpi display. The worst you can say is they are slightly less precise in their speech than is optimal.
        sesqu 16y ago
        Ah. So your position is that there is a distinction, but it's not lexically recognized. My position is it is lexically recognized, but not by enough people. It seems to me that a lot of people do draw a line between pixels and dots, and that a lot of people don't (but usually mean pixels). I don't know if there are proper authorities for this, but I consider the distinction important enough to warrant specific language. My dictionary here says that pixels are onscreen dots - I used to think the same, but now I consider pixels to be the samples in memory. I think you are with the dictionary, since you used the term "physical pixel". My adopted distinction meshes well with my ability to change the resolution of my desktop, measured in pixels, but not the resolution of my display, measured in dots. I agree that Bray can call it a 300dpi display - I didn't criticize him for it - and I explicitly translate that to a 300ppi natural resolution display. As noted above (according to Wikipedia), some manufacturers are now exploiting this by reporting such displays as 900 dpi, counting the subpixels as dots. Therefore I consider it important to state natural resolution ppi numbers for devices with natural resolutions, such as LCDs, and dpi resolutions for devices that don't have a natural representation of a pixel, such as CRTs. Representation numbers, ppi and dpp, I have yet to see anyone provide (maybe because there are too many resolutions already). tl;dr: It's confusing people, so make the distinction if you can.

by sesqu 16y ago

bonaldi 16y ago

No, DPI and PPI are literally the same thing. (Photoshop used to call what is now PPI "DPI"). "PPI" comes from people wanting a way to talk about the dpi of a digital image without including all the baggage and confusion of dpi, which too few people understand. There's no technical difference, however.

sesqu 16y ago
If they're the same thing, which thing is it? The number of pixels (virtual representations; samples) per inch of display, or the number of dots (physical representations; approximate components) per inch of display?
- bonaldi 16y ago
  You've got a false distinction there. It's the number of constituents that can be packed in per inch: whether those constituents are print dots, physical pixels, or utterly notional (as in displayed images).
  - sesqu 16y ago
    No, that's just the per inch part. I still need to know what the constituents being measured are, as logical pixel vs. physical dot makes all the difference: I don't care about the dot density, as long as there are enough of them; I care about the dots/pixel, and deeply about the actual inches. I ran into this problem as a kid, printing some images that had dpi metadata that the printer took literally, but I didn't know how to fix it back then so I ended up with a thumbnail print. Attaching ppi (!) metadata to images is stupid anyway, since the actually relevant information would be the inches (or the dots/inches, for designer decrees).
    - deleted 16y ago
      [deleted]
    - bonaldi 16y ago
      "I care about the dots/pixel" Yes, but those are two different dots you're talking about. What you actually care about is how many printer dots you get for each image pixel. There is a distinction, and I'm all for precision in language, but it's nothing more than a language distinction for the sake of clarity. It is not a technical distinction, is my point, and people like Bray aren't wrong to call this a 300dpi display. The worst you can say is they are slightly less precise in their speech than is optimal.
      - sesqu 16y ago
        Ah. So your position is that there is a distinction, but it's not lexically recognized. My position is it is lexically recognized, but not by enough people. It seems to me that a lot of people do draw a line between pixels and dots, and that a lot of people don't (but usually mean pixels). I don't know if there are proper authorities for this, but I consider the distinction important enough to warrant specific language. My dictionary here says that pixels are onscreen dots - I used to think the same, but now I consider pixels to be the samples in memory. I think you are with the dictionary, since you used the term "physical pixel". My adopted distinction meshes well with my ability to change the resolution of my desktop, measured in pixels, but not the resolution of my display, measured in dots. I agree that Bray can call it a 300dpi display - I didn't criticize him for it - and I explicitly translate that to a 300ppi natural resolution display. As noted above (according to Wikipedia), some manufacturers are now exploiting this by reporting such displays as 900 dpi, counting the subpixels as dots. Therefore I consider it important to state natural resolution ppi numbers for devices with natural resolutions, such as LCDs, and dpi resolutions for devices that don't have a natural representation of a pixel, such as CRTs. Representation numbers, ppi and dpp, I have yet to see anyone provide (maybe because there are too many resolutions already). tl;dr: It's confusing people, so make the distinction if you can.