PPI and Printing
P p I pixels per inch versus that's this topic right here when we talk about our workflow options this pp I issue pixels per inch. First off, if I change this number to five and hit enter. Okay. What is it going to do to the file? Absolutely nothing. If I change it to three billion people die. What will it do to the file? Nothing. Pp isa little numeric value that runs along with the file, stays with it wherever it goes and is only relevant when a person hits print hit, print it's. How many pixels prints are squished together on a piece of printed page? Aside from that it's, just a piece of metadata like everything else. So it is pretty much irrelevant in most parts of it to twenty five is a great default resolution it's, kind of in between the one fifty in the three hundred which kind of extremes of what you'd use for an encoded stock and for coded stock it's, middle of the road for most applications, it's fine it's actually has a mathematical description with it. It's based upon offse...
t printing. One hundred fifty line screen two point five times your to one point five times your half tone screen is a good resolution for half tone printing magazine is one hundred fifty line screen, uh one point five times one hundred fifty is to twenty five that's where that mathematical description comes in if you actually go into photoshopped into image resize image size, you can actually tell it what quality you want and it will choose to twenty five as a standard operation based upon putting in one fifty for your half time screen. Um, in terms of that so it's a great bass and I actually used to twenty five is a great base of printing because you could get away with a lot one fifty going down as faras one fifty you can get away with for a gallery, rap or canvas o r watercolor paper our campus rap. So one fifty the thing to remember about going down from two twenty five to one fifty it's almost half the file size yeah, meaning your file could be half a cz big and get away with a campus rap as opposed to a basic ah coded stock three hundred p p I is almost twice as big as two twenty five p p ay terms of file size um so again that's a huge amount of extra overhead for working on your image. If you're not going out to a metallic print, you might be able to get away totally fine with the two twenty five pp I file, so that will depend upon what you're putting to and whether you can get away with the two twenty five again, be cautious if you're going to a coded stock certainly be cautious with over sharpening your file. Um, and, um, so what happens if you have a what would be an image? You go into image size and let's actually go out of here and let's say done actually, let us go back into that and let's, open it back up this object into photoshopped proper, and we're going to go into image size, we're gonna go print, so here is that to twenty five that did right along with the file. But if I go here that instead of percent I go into inches, I can print out eight by eight image on this little crop square image of two twenty five p p I and you go. Well, you know what I really want, though, is this file to be? I needed to be in eleven by fourteen, okay? And I don't have re sample turned on, so it's got to be fourteen. I know that we have to do some cramping, so I needed fourteen pixels high for my print out and says, I'm sorry to do that, I can't push as many pixels together. Right you're not giving me I've got a set number of pixels right here this is a set number those of the dimensions of the file that is an absolute number p p I is a variable so when I tell it that I need this size says that's all you're giving me to work with so what do I do in this file? I've got this resolution I wanted it fourteen inches there's two things I could do either one say that's close to one fifty okay, I'll go to a gallery rap I can't do the metal print there's no way I would do a middle print on this thing or coded stock I might be able to get away with that would I take this upto one fifty knowing that that's kind of the minimum range do that a little bump in resolution? In other words, turn on re sampling and set this up to one fifty probably not I don't need to interpret waited up from ten megapixels tto eleven megapixels to do that because anytime you interpret your you're creating pixels that weren't there so it was so close to one fifty I'd probably get away with it but it's got to be fourteen inches and it needs to be on a glossy print so I really can't do one fifty I need that minimum of two twenty five and at two twenty five would I up press this to this file would I take what was a ten megapixel file and take it upto twenty five megapixel file yes I would especially taking advantage of this new automatic feature built into photo shop cc this automatic is using a brand new algorithm for doing the interpolation of the file and it does a very good job of uprising the file the best job that adobe has ever done over the years so if you do need a minimum amount of resolution for a file and you do need a present, do it inside a photo shop take advantage of auto I would take it to the minimum to twenty five I would not get greedy and take it up to three hundred I would do like a glossy print but maybe not a metallic print again you don't have enough that's really getting greedy I'm already taking in doubling the file size so again be real cautious doing anything more than that if I start off with a file that is really big that's three hundred p p I and I'm only going to take it down to a small little you know campus rap here what I reduced the file no just leave it at the full resolution there's no benefit to down raising it you know the printer will do that you go well I'm uploading it you know it's really big final in terms of uploading it up to my service bureau yes, if you want to take it down then you can take it down to what would be three hundred or something like that. Um, the last thing to think about is some people have a very set numeric value say two hundred forty or two hundred forty three point six to eight p p I is the optimum really cool divinely inspired pp I for doing great prince usually that's something related to an ancient printer that has a very set number of dots per inch dots per inch related to a device. Monitors have dots per inch. Printers have dots per inch out put his pee pee I not d p I in case you get confused with that that's the difference between a device has how many dots per inch can use to make an image this case like a screen or a printer? Pp eyes. How many pixels a print on a printed page? Um um uh in terms of d p I have a printer they go well a dp of a printer has fourteen hundred forty dp I you divide that by six and that means that they but the divine set for a pee pee I should be a direct mathematical portion of a d p I have a printer the problem is, especially with ancient printers is all in check printers use a random number of dots within there process was known a stochastic screening it's a random dither pattern there is no set number of dots in any portion of the print their arm or darts dots words darker through less dots where it's lighter they're random generated stochastic screen of prince there is no set number of dots per linear inch on an ink jet printer. Therefore in my mind there's no sense to having a direct representation mathematical portions of it because there is no set number and maybe a fourteen hundred forty dp I printer it's never printing out fourteen hundred forty dp I exactly because of this random pattern, very different in half tone screening and why we have things like two hundred twenty five four half tone dot if you're going out to a magazine, then it makes a little bit more sense and that's where the two hundred twenty five to three hundred come in those are direct percentages of the half tone screen resolution of a magazine two twenty five is great you can go up to three hundred you want that's based upon your half tone screen if you want to figure out if you're going out to a different half tone screen now there are also stochastic screening for half tone offset lithography can use stochastic screening again that would become a variable number bladder, bladder blood the bottom line is to twenty five is a great general pp. I won fifty and get away with it for encoded stock and canvas three hundred if you're going to go out for metal and coded stock, if you need to appraise the file, do it in photoshopped. Take advantage of the auto resolution, take it up to the minimum amount that you need for the type of media that you're working on. General glossy prints to twenty five metallic prince three hundred somewhere in there don't get too greedy and say, well, I wanted to be a poster. If you do have an iphone shot and it has to fill up the wall, knock yourself out, blow it up here, do it, take it for granted, the person's going to be looking at it from, you know, fifty feet away and do your excessive sharpening and that you're going to take it definitely take advantage of things like clarity and maybe even in photo shop. You'll take adventure things like high pass popping, which is a high pass filter and you know, but we haven't gone into that.