I'm seeing some real confusion over PPI/DPI amongst the community.

Metronome49Metronome49 Member Posts: 297
edited November -1 in Art, Graphics, Music and Sound
I know that GameSalad tells you to set your images at 72 ppi, which is fine, if you have to tell someone a number, it's the number that has been used since we were designing for CRTs, but when designing for screen, ppi is completely irrelevant... so, I don't understand what GameSalad could possibly be doing with your ppi metadata. Is there a point at which we think someone will PRINT the images from our games?

I think it stems from a complete misunderstanding of what ppi is, and why it exists. I urge everyone to read this article, which is one of the best at explaining a difficult concept.

http://www.rideau-info.com/photos/mythdpi.html

Now, 72 ppi is a fine recommendation, if you must make a recommendation, and you must make a recommendation, because people will ask, but please do not think that the ppi setting actually means anything significant to designing for a screen.

Now, does GameSalad actually do anything with ppi metadata? If so, why?
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Comments

  • DizkoDizko Member Posts: 498
    This is just a guess. But I reckon that because GameSalad does not recognize the pixel density of your bitmap it therefore alters the dimensions of the imported bitmap. For example (for the sake of easy math) if you made an image that you wanted to be 64x64 @ 144 dpi it would then import into GS as a 128x128 image instead, because it has double the pixels.

    To be honest I don't know the real reason, but thats my guess.
  • Metronome49Metronome49 Member Posts: 297
    @Dizko

    It doesn't have double the pixels, it's either 64x64 or it isn't. If it is 64x64 at 1 or 1,000 ppi, it still has the same amount of pixels.

    Your assumption is based off the faulty idea that 72dpi means a 1 to 1 pixel ratio, so doubling the ppi would double pixels... but 72 dpi doesn't incur a 1 to 1 pixel ratio, 1 to 1 pixel ratio is inherent on screens. 72 dpi incurs a 72 pixel to inch conversion ratio for printing.

    In other words ppi is PRINT INSTRUCTIONS. Nothing more.
  • gyroscopegyroscope I am here.Member, Sous Chef, PRO Posts: 6,598
    Metronome49 said:

    In other words ppi is PRINT INSTRUCTIONS. Nothing more.

    Hi Metronome, no sorry, ppi has nothing to do with print instructions as such, dpi has. And that article is sure making a mountain out of a molehill.

    ppi stands for pixels per inch. dpi stands for dots per inch. And there is a direct relationship, both being about resolution, and comparable resolution at that. A pixel is a dot, simple as that, . What's not the same, is the actual resolution - how many dots or pixels you "see"- comparing quality of printed image with a monitor screen.

    In other words, the ideal best quality of printing is 300dpi, which would look like just over 4 times larger on a website; one's variable visually-speaking - printing; one's fixed - monitor screen. Changing the image resolution to a picture in Photoshop doesn't affect it's visual resolution, you've got to zoom in for that). You know that, of course.

    But printing resolution is variable, where I could print a same-size pic from the ideal high quality 300dpi all the way down to 72dpi or below if I wanted. It's how many dots/ "pixels" are overlaid with each other when printing which determines it's visual quality which can change of course, pixels/"dots" on screen lie next to each other always.

    As I say, there is a fixed relationship, where dpi does in fact equal ppi, just not how it's seen visually. If I want to print something at a certain size at 300dpi, I have to set the image up in Photoshop as 300ppi.

    I was a professional graphic designer for 30 years, and I can tell you not one person in the printing or graphic design industry here in the UK deviated from this way of thinking.

    ""You are in a maze of twisty passages, all alike." - Zork        temp domain http://spidergriffin.wix.com/alphaghostapps

  • JeffreyShimaneJeffreyShimane Member Posts: 372
    Metronome49 said:
    In other words ppi is PRINT INSTRUCTIONS. Nothing more.

    Project Masala = Print Your Apps! ;)

    - Jeff
  • jb15jb15 Member Posts: 602
    Crazy. I've tried understanding this issue before, and here's what I've figured out: If it's not blurry, be happy. :)

    But yeah, I sure wish there was a image guide to GS somewhere.
  • DizkoDizko Member Posts: 498
    No you're misunderstanding and getting hostile (over what, I don't know).

    The assumption of the 1 to 1 ratio comes inherently from the assumption that you or anyone one else would be working in pixels and not inches.

    If you alter the DPI of an image after the fact, be it intentionally or not, it will then alter the dimensions of said image. This is why it's a problem for GS (in theory). It seem that some applications that people use to generate graphics will start in 72dpi but then save it in an odd off number like 73, thus altering the dimensions of the original image.

    So you're right in the sense that it doesn't matter what your DPI is, as long as it's consistent from when you created the new document in whatever app you're using to when you save it.

    I reckon that GS suggests you use 72dpi simply because of the fact that a majority of bitmap editing tools default to that number. I'm not really sure what you're all up in arms about.
  • jonmulcahyjonmulcahy Member, Sous Chef Posts: 10,408
    i think apple's Human interface guidelines recommend 72dpi, but i can't find it at the moment.

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  • Metronome49Metronome49 Member Posts: 297
    @gyroscope

    I'm currently a professional Graphic Designer / Web Designer, and you're all wrong. I know that dpi is different from ppi, but when we're talking about the digital publishing age they have become interchageable. What you're really missing here, is "an inch of what?" pixels per inch OF WHAT? It's not pixels per inch of screen, because that doesn't work... ever... at all. A 72 dpi image does not have 72 pixels per inch unless it is a 72 pixel wide image and is being viewed on a monitor with 72 pixels per inch... and they don't have those anymore. The ppi is irrelevant until you print it. DPI is printers resolutions nomenclture, because they make dots, and ppi is a conversion factor from pixels to printed physical space. Hypothetically if you had a 72 dpi printer, and a 72 ppi image, each halftone dot would represent 1 to 1 a pixel.

    "how many dots or pixels - are used for quality of image compared with a monitor screen."
    What is it that you even mean here? Monitors are wildly varied in the amount of pixels per inch.

    "the ideal best quality of printing is 300dpi"
    That would really depend on your printer, some print processes, used for fine-art books and such, go much higher. 300 dpi is really only ideal because you eyes can't pick out the halftone dots at regular reading distance.

    "...which would look like 72ppi on a website"
    This doesn't mean anything. What does 72 dpi look like? Your monitor doesn't have 72 pixels per inch, so why would it LOOK like it does? It doesn't. The website shows the images pixels, at the size of the screens pixels... which depends on the screen.

    "So 144ppi shows as 72ppi on screen"
    No it doesn't... it shows at whatever the screen has, and no screens have 72 dpi anymore.

    "and I can tell you not one person in the printing or graphic design industry here in the UK deviated from this way of thinking."
    This is true, but it's not because it's the correct way of thinking. It's because the truth is really complicated for people to grasp, because people want absolutes, so early on there was just a "set at 72 ppi for screen and 300 ppi for print and forget about it", which is fine until lack of understanding causes people to run into problems like assuming that ppi is causing issues.

    That being said, it's possible, but very improbable, that GameSalad is using the ppi for anything, because it just doesn't make any sense. If they are measuring the ppi on the png, then algorithmically making a change to the imported images actual pixels, then they should stop, because ppi is used exclusively for printing.
  • gyroscopegyroscope I am here.Member, Sous Chef, PRO Posts: 6,598
    jonmulcahy said:
    i think apple's Human interface guidelines recommend 72dpi, but i can't find it at the moment.

    That'll be ppi if referring to computer screens, surely? ;-)

    ""You are in a maze of twisty passages, all alike." - Zork        temp domain http://spidergriffin.wix.com/alphaghostapps

  • Metronome49Metronome49 Member Posts: 297
    Dizko said:
    No you're misunderstanding and getting hostile (over what, I don't know).

    The assumption of the 1 to 1 ratio comes inherently from the assumption that you or anyone one else would be working in pixels and not inches.

    If you alter the DPI of an image after the fact, be it intentionally or not, it will then alter the dimensions of said image. This is why it's a problem for GS (in theory). It seem that some applications that people use to generate graphics will start in 72dpi but then save it in an odd off number like 73, thus altering the dimensions of the original image.

    So you're right in the sense that it doesn't matter what your DPI is, as long as it's consistent from when you created the new document in whatever app you're using to when you save it.

    I reckon that GS suggests you use 72dpi simply because of the fact that a majority of bitmap editing tools default to that number. I'm not really sure what you're all up in arms about.

    Dizko said:
    No you're misunderstanding and getting hostile (over what, I don't know).

    The assumption of the 1 to 1 ratio comes inherently from the assumption that you or anyone one else would be working in pixels and not inches.

    If you alter the DPI of an image after the fact, be it intentionally or not, it will then alter the dimensions of said image. This is why it's a problem for GS (in theory). It seem that some applications that people use to generate graphics will start in 72dpi but then save it in an odd off number like 73, thus altering the dimensions of the original image.

    So you're right in the sense that it doesn't matter what your DPI is, as long as it's consistent from when you created the new document in whatever app you're using to when you save it.

    I reckon that GS suggests you use 72dpi simply because of the fact that a majority of bitmap editing tools default to that number. I'm not really sure what you're all up in arms about.

    Not sure how I was hostile, but I apologize.

    Altering the ppi of an image after the fact makes no difference on the actual size of the image, unless you are resampling and resizing the image while doing it, which is totally different from ppi.

    For example, in Photoshop, if you take an image that's 72 ppi, and change it to 300 ppi, nothing changes... unless you have "resample image" checked, which is something totally different. That is actually changing the amount of pixels in the image. But resampling isn't the same as changing ppi.
  • Metronome49Metronome49 Member Posts: 297
    jonmulcahy said:
    i think apple's Human interface guidelines recommend 72dpi, but i can't find it at the moment.

    They probably just got rid of it after monitors stopped having 72 ppi. Once upon a time the myth of 72 ppi was born because a monitor actually had 72 ppi and then when you printed, the image was the same size printed as it was on your monitor... but that was a long time ago.
  • gyroscopegyroscope I am here.Member, Sous Chef, PRO Posts: 6,598
    Metronome49 said:
    @gyroscope

    I'm currently a professional Graphic Designer / Web Designer, and you're all wrong. I know that dpi is different from ppi, but when we're talking about the digital publishing age they have become interchageable.

    Not in the professional world it hasn't, (printing industry pros/computer industry pros) and that's precisely why people get confused. dpi is a printing term, ppi is a computing term. But because one pixel represents one dot printed, some people use the other term; no big deal though, just not accurate. I'm not lessening you professional status in any way here, by the way.
    Metronome49 said:
    What you're really missing here, is "an inch of what?" pixels per inch OF WHAT? It's not pixels per inch of screen, because that doesn't work... ever... at all. A 72 dpi image does not have 72 pixels per inch unless it is a 72 pixel wide image and is being viewed on a monitor with 72 pixels per inch... and they don't have those anymore.

    An inch of what when referring to dpi is an actual inch measurement. the inch referred to in ppi is referring to the printed inch, the comparable dots per inch. (72pixels per actual measured inch on computer monitors have never existed) But for certain, although different sizes, for every dot there's a pixel. For every pixel there's a dot. A pixel is made with light, a dot a tiny spot of ink as you know, so it's just that they are seen (visually and measurably) different.
    Metronome49 said:
    The ppi is irrelevant until you print it. DPI is printers resolutions nomenclture, because they make dots, and ppi is a conversion factor from pixels to printed physical space.

    "The ppi is irrelevant until you print it." ppi is relevant in itself even if you don't want to print, because you have to get the ppi to 72 for optimal "performance". Some monitors take 92ppi, I think?
    Metronome49 said:
    DPI is printers resolutions nomenclture, because they make dots, and ppi is a conversion factor from pixels to printed physical space. Hypothetically if you had a 72 dpi printer, and a 72 ppi image, each halftone dot would represent 1 to 1 a pixel.

    Not much of a conversion factor: 1 pixel as an amount equals 1 printed dot; and that's not hypothetical. Also, if I may point out, doesn't have to be a dot from a halftone; the dots can be (and usually are) the same size to each other, other than printing photos/images as halftones.
    Metronome49 said:

    "how many dots or pixels - are used for quality of image compared with a monitor screen."
    What is it that you even mean here? Monitors are wildly varied in the amount of pixels per inch.

    No they don't visually, they're all 72 pixels per "inch". That doesn't vary. If you make a 72ppi image in Photoshop and another at 300dpi, at the same size, they are identical. Printed images vary though visually; at size for size, they can have different visual resolutions.
    Metronome49 said:
    "the ideal best quality of printing is 300dpi"
    That would really depend on your printer, some print processes, used for fine-art books and such, go much higher. 300 dpi is really only ideal because you eyes can't pick out the halftone dots at regular reading distance.

    You can print higher than 300dpi but for normal 4-colour professional printing, your eye will see no discernable improvement in quality. And lots of brochures, catalogues, cd inserts, you name it, are printed at 300dpi. 240dpi can be used without hardly any loss of visual quality to the image.
    Metronome49 said:
    @gyroscope

    "So 144ppi shows as 72ppi on screen"
    No it doesn't... it shows at whatever the screen has, and no screens have 72 dpi anymore.

    Try the photoshop test I described above then. do one at 72ppi, one at 144ppi. They'll be the same size.
    Metronome49 said:
    @gyroscope

    "and I can tell you not one person in the printing or graphic design industry here in the UK deviated from this way of thinking."
    This is true, but it's not because it's the correct way of thinking. It's because the truth is really complicated for people to grasp, because people want absolutes, so early on there was just a "set at 72 ppi for screen and 300 ppi for print and forget about it", which is fine until lack of understanding causes people to run into problems like assuming that ppi is causing issues.

    The "truth" as you put it IS very easy to grasp. People just make it over-complcated, that's all. And if you want to think that the tens, if not hundred's of people I met in my time in the printing industry were thinking wrong, then go ahead and think it; but you are wrong in saying that.
    Metronome49 said:
    @gyroscope

    That being said, it's possible, but very improbable, that GameSalad is using the ppi for anything, because it just doesn't make any sense. If they are measuring the ppi on the png, then algorithmically making a change to the imported images actual pixels, then they should stop, because ppi is used exclusively for printing.

    You're overcomplicating again; of course GameSalad "uses the ppi for something" to paraphrase you, but I've written enough now.

    ""You are in a maze of twisty passages, all alike." - Zork        temp domain http://spidergriffin.wix.com/alphaghostapps

  • DizkoDizko Member Posts: 498
    Metronome49 said:
    Not sure how I was hostile, but I apologize.

    Altering the ppi of an image after the fact makes no difference on the actual size of the image, unless you are resampling and resizing the image while doing it, which is totally different from ppi.

    For example, in Photoshop, if you take an image that's 72 ppi, and change it to 300 ppi, nothing changes... unless you have "resample image" checked, which is something totally different. That is actually changing the amount of pixels in the image. But resampling isn't the same as changing ppi.

    Well that's precisely what I'm saying. The ppi (dpi whatever) doesn't really matter. I suspect GS only says 72 dpi because that's what the defaults are in PS etc. I think people encountering problems with ppi/dpi is because they've accidentally re-sampled their images by changing that number thus altering the dimensions to a non-power of 2 texture and ultimately shows up blurry in GS.

    Like you I'm a designer, I've only ever worked in TV and with game engines. In TV we don't care about DPI, only aspect and pixel ratios. With game engines, all we care about is texture size.
  • gyroscopegyroscope I am here.Member, Sous Chef, PRO Posts: 6,598
    Dizko said:
    The ppi (dpi whatever) doesn't really matter.

    What about producing images for Resolution Independence then? ;-)

    ""You are in a maze of twisty passages, all alike." - Zork        temp domain http://spidergriffin.wix.com/alphaghostapps

  • dotsonj23dotsonj23 Member Posts: 316
    Metronome49 said:

    That being said, it's possible, but very improbable, that GameSalad is using the ppi for anything, because it just doesn't make any sense. If they are measuring the ppi on the png, then algorithmically making a change to the imported images actual pixels, then they should stop, because ppi is used exclusively for printing.

    I believe they do use it for something (unfortunatley). In fact, when I tested a 512 x 512 image with a 2 pixel line horizontally along the bottom of the image and a 512 x 256 image with a 2 pixel line horizontally across the bottom of the image (each image having different PPI) and then lined up the bottoms of the images with each other in GS, the lines do not match up when in gameplay on my IPAD but do match up when in GS Creator. They appear to be 1 pixel off. The only way to fix it was to stretch the second image in GS to 512 x 256.5 and offset the images by .5 Y value. That fixed the issue. But clearly there is a problem here.
  • Metronome49Metronome49 Member Posts: 297
    gyroscope said:
    What about producing images for Resolution Independence then? ;-)

    Resolution independence traditionally has referred to Vector Graphics, because they have no pixels, they are mathematical data, they are only drawn in pixels on screen. Resolution independence in regards to Retina display means that you provide two different images at different sizes that are dropped in depending on which resolution the device has.
  • gyroscopegyroscope I am here.Member, Sous Chef, PRO Posts: 6,598
    Thanks for the info Metronome but I know what Resolution Independence is/Retina Display is about. I was asking a rhetorical question to Ditzo's comment of "The ppi (dpi whatever) doesn't really matter". I was implying, with the friendly - ;-) - that ppi does matter. Cheers.

    ""You are in a maze of twisty passages, all alike." - Zork        temp domain http://spidergriffin.wix.com/alphaghostapps

  • Metronome49Metronome49 Member Posts: 297
    @gyroscope

    "But because one pixel on screen represents one dot printed, some people use the other term;"

    It doesn't though. If I print a 72 ppi image on a 300 dpi printer, then multiple dots comprise one pixel, the pixel is larger, and very visible, and is made of multiple dots. Only with 300 ppi would it be 1 to 1.

    "72pixels per actual measured inch on computer monitors have never existed"

    It did. Once upon a time when the desktop publisher revolution happened, the Macintosh did.

    "Try the photoshop test I described above then. do one at 72ppi, one at 144ppi. They'll be the same size."

    That's true, but it has nothing a 71ppi, nothing on screen is ever shown at 72ppi, they just show their pixels, they appear the same size as each other, on your screen, because they have the same amount of pixels, their resolution is irrelevant. They would not appear the same size on two separate monitors.

    "You're overcomplicating again; of course GameSalad "uses the ppi for something" to paraphrase you, but I've written enough now."

    Forgive me for a thirst for understanding, but I don't see any of this as that complicated personally. They don't need ppi, in fact... pngs discard resolution data. They don't even carry ppi data in their file.
  • Metronome49Metronome49 Member Posts: 297
    gyroscope said:
    Thanks for the info Metronome but I know what Resolution Independence is/Retina Display is about. I was asking a rhetorical question to Ditzo's comment of "The ppi (dpi whatever) doesn't really matter". I was implying, with the friendly - ;-) - that ppi does matter. Cheers.

    Respectfully, I understood what you were implying, but the implication is wrong, that's why I explained it. The pixel size is what provides the resolution independence, not the resolution of the image.
  • Metronome49Metronome49 Member Posts: 297
    Another really good article on the matter:

    http://www.webdesignerdepot.com/2010/02/the-myth-of-dpi/
  • capitalcarnagecapitalcarnage Member Posts: 371
    I had a nasty DPI from a trip to Spain in 96, Luckily the doctor gave me a cream and a pill to take, cleared it right up!
  • Metronome49Metronome49 Member Posts: 297
    @CapitalCarnage

    The other night I was out driving after a wild party and got pulled over and charged with a DPI. Lame.
  • gyroscopegyroscope I am here.Member, Sous Chef, PRO Posts: 6,598
    Metronome49 said:
    @gyroscope

    "But because one pixel on screen represents one dot printed, some people use the other term;"

    It doesn't though. If I print a 72 ppi image on a 300 dpi printer, then multiple dots comprise one pixel, the pixel is larger, and very visible, and is made of multiple dots. Only with 300 ppi would it be 1 to 1.

    Hi again; no sorry, Metronome49 you are incorrect; 279 ppi equals 279 printed ink dots. 125 ppi equals 125 printed ink dots, etc; whatever number you think of. The only difference, as I say, (and you've mentioned) is visually, whereby printed "pixels" i.e the dots overlay/overlap each other; and pixels sit next to each other; but size for size, printed images vary in VISUAL resolution as opposed to computer monitors which are fixed.
    Metronome49 said:

    It did. Once upon a time when the desktop publisher revolution happened, the Macintosh did.

    Thanks for that, I didn't know that.
    Metronome49 said:

    "Try the photoshop test I described above then. do one at 72ppi, one at 144ppi. They'll be the same size."

    That's true, but it has nothing a 71ppi, nothing on screen is ever shown at 72ppi, they just show their pixels, they appear the same size as each other, on your screen, because they have the same amount of pixels, their resolution is irrelevant. They would not appear the same size on two separate monitors.

    Yes, I've never said any different; i'll say again, visually, they are different, because one is fixed, one's not, size for size. If you've a 300ppi pic showing the same size as a 72ppi pic, it's still a different resolution, blown up over 4 sizes larger equals overaly 4 times more info on a printed page. i think we're going around in circles with this particular argument.
    Metronome49 said:

    "You're overcomplicating again; of course GameSalad "uses the ppi for something" to paraphrase you, but I've written enough now."

    Forgive me for a thirst for understanding, but I don't see any of this as that complicated personally. They don't need ppi, in fact... pngs discard resolution data. They don't even carry ppi data in their file.

    Who am I to forgive people ;-) No worries there anyhow; I've a thirst for understanding too; we never stop learning, I know! OK, not overcomplicating but maybe confusing the issue? Of course, you'll disagree with me there!!

    OK, as to ppi, forget about it if you like; I'll pay close attention to it when I'm producing graphics for GS projects... ;-) (THere's that friendly wink again...)

    ""You are in a maze of twisty passages, all alike." - Zork        temp domain http://spidergriffin.wix.com/alphaghostapps

  • Metronome49Metronome49 Member Posts: 297
    @gyroscope

    "Hi again; no sorry, Metronome49 you are incorrect; 279 ppi equals 279 printed ink dots. 125 ppi equals 125 printed ink dots, etc; whatever number you think of. The only difference, as I say, (and you've mentioned) is visually, whereby printed "pixels" i.e the dots overlay/overlap each other; and pixels sit next to each other; but size for size, printed images vary in VISUAL resolution as opposed to computer monitors which are fixed."

    Take a 30px by 30px image, at 300 ppi, and print it. Now take that same file, and change the ppi to 1, then print it. Obviously on the file that has 1 ppi, every pixel in the document is printed as one physical inch. And assuming the printer is 300 dpi, then each document pixel is represented by 300 dots. How can 1 pixel = 1 dot if you just printed a pixel that was made of 300 dots? It has to be a conversion. The printer has a fixed dpi, the monitor has a fixed ppi, the difference is that the monitor does not use the ppi information.

    Maybe I am confusing the issue for others, and if they are confused, just set it to 72, it'll be fine.

    Now, when I get home I'm going to do a test, to see what Gamesalad is doing with the ppi information...
  • Metronome49Metronome49 Member Posts: 297
    Dizko said:
    Well that's precisely what I'm saying. The ppi (dpi whatever) doesn't really matter. I suspect GS only says 72 dpi because that's what the defaults are in PS etc. I think people encountering problems with ppi/dpi is because they've accidentally re-sampled their images by changing that number thus altering the dimensions to a non-power of 2 texture and ultimately shows up blurry in GS.

    Like you I'm a designer, I've only ever worked in TV and with game engines. In TV we don't care about DPI, only aspect and pixel ratios. With game engines, all we care about is texture size.

    Right. I feel like people wouldn't encounter this problem if they stayed out of the ppi entirely. It's irrelevant.
  • Metronome49Metronome49 Member Posts: 297
    Well...

    Tested this. It most definitely changes your images in the preview window... but only if they OVER 72 ppi.

    An 72 ppi image, and a 1 ppi image, and a 35 ppi image, all look the same after import, with the same amount of pixels they came with.. But a 144 ppi image, is imported with less pixels than the actual image has... half I would presume...

    I have no idea why they make it do this... but I'm definitely keeping my images at 72ppi or lower.
  • gyroscopegyroscope I am here.Member, Sous Chef, PRO Posts: 6,598
    Metronome49 said:
    @gyroscope

    "Hi again; no sorry, Metronome49 you are incorrect; 279 ppi equals 279 printed ink dots. 125 ppi equals 125 printed ink dots, etc; whatever number you think of. The only difference, as I say, (and you've mentioned) is visually, whereby printed "pixels" i.e the dots overlay/overlap each other; and pixels sit next to each other; but size for size, printed images vary in VISUAL resolution as opposed to computer monitors which are fixed."

    Take a 30px by 30px image, at 300 ppi, and print it. Now take that same file, and change the ppi to 1, then print it. Obviously on the file that has 1 ppi, every pixel in the document is printed as one physical inch. And assuming the printer is 300 dpi, then each document pixel is represented by 300 dots. How can 1 pixel = 1 dot if you just printed a pixel that was made of 300 dots? It has to be a conversion. The printer has a fixed dpi, the monitor has a fixed ppi, the difference is that the monitor does not use the ppi information.

    Maybe I am confusing the issue for others, and if they are confused, just set it to 72, it'll be fine.

    Now, when I get home I'm going to do a test, to see what Gamesalad is doing with the ppi information...

    your example of a 300dpi printer is the maximum dpi it can print, not the only resolution it can print. it can print anything less than that, but anything more, you won't get better quality (and as I say, 300dpi 4 colur printing is visually no worse than anything higher, as it happens).

    So, if you print a 1 pixel per inch image (1ppi) you'll get one dot on your 300dpi max.res.printer. If you have 20 ppi, one row, ipixel high, you'll get 20 dots of ink, etc.

    As for your explanation about ppi not mattering, and that it's the pixel size that changes, that's incorrect too. Pixel size on a computer screen doesn't and can't change in size; it's either on or off, showing a colour or not. What does change is the resolution of the screen, the iPhone4 being 4 times more pixels on screen than previous models (although they are smaller in size to previous models, but neither change, just are the sizes they are).

    ppi is not unimportant i.e is impertant to consider, when using Resolution Independence, because you have to make sure that all images are twice the size (4 times the resolution).

    It seems you've disagreed with most things I've written here in your thread; I don't think we will ever agree so I'm going to leave it that we "beg to differ".

    ""You are in a maze of twisty passages, all alike." - Zork        temp domain http://spidergriffin.wix.com/alphaghostapps

  • StormyStudioStormyStudio United KingdomMember Posts: 3,989
    wow!

    I read this when it was one comment...went to the pub came back half drunk...and now I have no idea what's being said...please summarise in 10 words or less...
  • gyroscopegyroscope I am here.Member, Sous Chef, PRO Posts: 6,598
    stormystudio said:
    wow!

    I read this when it was one comment...went to the pub came back half drunk...and now I have no idea what's being said...please summarise in 10 words or less...

    Heh, hope you enjoyed your ale, Jon! (I'm going to a real ale festival in Essex tomorrow as it happens...)

    OK, I'll try to summarize:

    Some people think that the term pixels per inch and dots per inch are interchangeable. I disagree: when I look under a glass on a piece of printed material, I'm not looking at pixels as far as I'm concerned, i'm looking at printed dots. When I look at a computer screen really close, not only do I get boss-eyed but I can vaguely make out pixels, not printed dots, of course.

    Some people think that ppi isn't important, and even if it is, only when dealing with printing. I think that pixels per inch is "important" in GS and other programs because...aah, you know why.

    Some people think that there's no relationship as such between ppi and dpi. I say there is a direct relationship concerning amount. For every pixel (not necessarily shown on screen of course) that is in the ppi resolution, that'll be the exact same amount of dots printed.

    I could go on, but that's some of the main points boiled down. I think I am correct in these aspects, others' don't. I think others are incorrect, they don't. Roll on the ale festival.

    ""You are in a maze of twisty passages, all alike." - Zork        temp domain http://spidergriffin.wix.com/alphaghostapps

  • SlickZeroSlickZero Houston, TexasMember, Sous Chef Posts: 2,870
    stormystudio said:
    wow!

    I read this when it was one comment...went to the pub came back half drunk...and now I have no idea what's being said...please summarise in 10 words or less...

    Debating over ppi and dpi will get you nowhere here.
    Warning There was an error rendering this rich post.
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