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30

I like the accepted answer, it has good advice, but I thought I'd expand on it a bit. For wall sized graphics and large banners (e.g 3m x 5m), what is an acceptable PPI/DPI for print. Here's definitions, so we know what we're talking about. DPI = Dots per inch = units used to measure the resolution of a printer LPI = Lines per inch = The offset ...


19

In general you should use vector graphics in the artwork wherever practical, and deliver final artwork to the printer in PDF or other vector format. Your finished print will then be limited only by the output resolution of the print device. This is particularly important with text and line art -- visible rasterization in the finished print will be very ...


15

I've always thought DPI was somewhat of a misnomer... It really only applies if you are printing an image, otherwise, well, pixels are pixels. For an image on a site, well, it really doesn't matter, just get as many as possible, to fit the required size. Printers vary somewhat, but around 300 DPI is usually a good rule of thumb for anything around the size ...


10

A pixel (the word was originally coined, iirc, by IBM and derives from "picture element") is the smallest indivisible unit of information in a digital image. Pixels may be displayed, or they may be printed, but you can't divide pixels into smaller pieces to get more information. How many channels and bits per channel make up one pixel is the measure of how ...


8

Using File → Save for Web and entering the dimensions will do what you're after. Also, Illustrator uses vector scaling, so the results are better than if you tried the same thing in Photoshop — entering dimensions that don't match the document in Photoshop means the image will be bitmap scaled. Please note that you have to click Apply after changing the ...


7

I recently read jrista's marvellous q&a from photo.stackexchange. While the question is titled "How do I generate high quality prints with an ink jet printer?" it covers DPI & PPI relationship to quite an extent and has real-world print examples. Current Q&A contents: Summary Detailed Explanation Empirical Studies: Does PPI really matter? ...


7

Grande format resolutions, as various folks have pointed out, depend on viewing distance. Several answers refer to line screens, but technology has moved on. Very few, if any, grande format jobs are printed that way, and in any case, none of the answers indicated how to translate from PPI (dots) resolution in Photoshop to LPI (lines of dots at different ...


7

If the printer is asking for 600dpi, it means [he] either didn't understand the question or there has been a failure to communicate. 600dpi (dots per inch) is the resolution at which your billboard will be printed. There was a time, in the Long Long Ago, when that would have been considered pretty high-resolution stuff -- I remember having posters printed ...


7

Should my images be saved at a specific PPI? No. iOS ignores PPI (pixels per inch) stored inside images. However, the pixel dimensions of your images do matter, so make sure you get those right. It’s also important to ensure your 2× images are exactly double the dimensions of your 1× images and that elements within the image are in the same ...


6

Did you change the pixel dimensions as well? DPI is typically meta-information to tell a printer how large to print the image. It normally doesn't have any affect on the actual pixel dimensions of the image. If that's the case, than the difference is likely that you saved the image with a high JPG compression setting. The best way for us to determine ...


6

How close are you going to view the 4' canvas? Is reducing the dpi really going to adversely affect printing on a coarse material like cotton or silk. Thats coarse relative to smooth glossy photo prints, for example. See this recent question: What DPI should a large format artwork for print be done at?


6

By default browsers display images at the native screen resolution i.e. one pixel in the image maps to one pixel on the screen. The browser ignores any resolution value defined within the image file. You can of course override this behaviour by specifying a width and/or height value for the image, either as parameters on the <img> element or as CSS ...


5

DPI (digital dots or pixels)/PPI defined: 300 dpi/ppi = 300 pixels used for every 1 inch line of ink coverage. 1000 pixels will yield a 3.3333 inch line @ 300 dpi of resolution DPI and PPI have been used interchangeably (though not always accurately) since pixels entered the printing industry. DPI comes from halftone/screen dots in offset printing. If a ...


5

ppi = pixels per inch = typically used as a measurement for screens (the iPhone 4 has twice the ppi as the iphone 3) dpi = dots per inch = typically used as a print measurement and refers to the number of pixels in the image that will be used to render 1" on paper scaling = this is a loaded term and why the answer isn't simple. For raster images, you can ...


4

As Horatio says, if it looks good, it's probably fine. There are two schools of thought on upsampling: One says, "Never, ever upsample"; the other says, "Hey, what the heck, upsampling rocks." In almost all cases I side with the former. Upsampling adds nothing but "best guesses" to the image. It specifically doesn't add any image information (I don't care ...


4

Specifically on PPI for web or other on-screen images: 72PPI (or 75, or 96) is a myth. Yes, there is a figure which applications use to decide how many pixels to use to render fonts specified in points, but this hasn't got any relevance to images, other than: if your Photoshop document is 72ppi, it doesn't matter if your font units are set to points or ...


4

Roger's right. You WILL NOT be in trouble at 150 ppi for an inkjet-type print process, especially at that size. But let's pretend that you can't change the 300 ppi requirement. The problem you are running into is memory, and it may be an impossible hill to climb without upgrading your hardware, but here are some basic steps that can mitigate the problem: ...


4

Well, where I come from 400x600cm is 4x6 meters. :-) 30 dpi for final output is more than enough for a billboard of that size. It's not unusual for final output to be 12-15 dpi in this context. The usual professional billboard workflow in Photoshop is to build the image at a small scale with high ppi (e.g., 4x6cm @ 300 ppi), but in this case you can work ...


4

There's lots of questions on this site pertaining to image resolution. Reading through those will help. The bottom line is that (until recently) screens are much lower resolution than printers are. Most screens are around 100 pixels per inch and most printers can do 300+ ppi. As such, you typically need to make two versions of your images. A lower ...


4

It depends on the usage the final file will be put to. If it's for web, definite dimensions could be similar or proportionately higher (never lower) to the dimensions expected to be shown in the final webpage (it can then exported in required dimensions using "Save for Web" functionality. If it's for print, it will again depend upon the quality of the ...


4

In all my years of working with Photoshop, the only one that really stands out to me (aside from "print" and saving to other PPI-sensitive formats like PDF, obviously) is the type tool. But that's primarily because the type tool always defaults to points (even if you pull up the type dialog and type in pixels, it'll just convert it to points for you). Still, ...


4

You need to be using File > Save For Web & Devices The Save For Web option in Photoshop strips away all of the extra info in the images to make them as small as possible. In most cases, unless you need transparency, I would use JPG around 70-90 Quality. There isn't too much of a difference there. PNGs are nice for crisp & transparent pictures, but ...


4

For live trace, it may be better to scale it up to larger pixel dimensions (2-3x), place it, and then trace it. This way you provide more data for the trace. Quality loss from over scaling the raster image is OK in this case because you will be using it as an intermediary step to the vector. IGNORE PPI, the only thing that matters is pixel dimension.


4

800 pixels by 800 pixels and need to convert them in Photoshop to 72 ppi for web use (at the same size: 800px by 800px). There's no conversion to do. If they're 800 pixels by 800 pixels, that's it, they're the size you need. However, 300ppi at 800px by 800px is like a 2.3" by 2.3" picture, so are you sure the files are currently at 800pixels by ...


3

In general, Pixels per Inch is for screen resolutions and Dots per Inch is for print resolutions, as lawndartcatcher says, but when you're dealing with an image that will be printed at a specific size, it is correct to use Pixels per Inch (because the image is in pixels) regardless of the number of dots per inch that the printer will lay down on the paper. ...


3

1) This article explains the difference between DPI and PPI the best I've seen thus far. In short, DPI (Dots per inch) has to do with the specific printer / print method you're using, whereas PPI (pixels per inch) refers to the exact number of pixels in your image. 2) No. 72 PPI won't magically become higher res. The old programming term is GIGO. You might ...


3

300 dpi is the norm for most printers, but it all depends on the way you'll be printing. High-end offset printers will need 300 dpi. Kinkos? Not so much. You can get away with 120 dpi, but I wouldn't go any lower than that. You will definitely see some loss in quality up close, but if you're not going with a high end print and you're planning on doing this ...


3

You can use the build in Preflight function. [I don't know when it has been introduced but its there in Acroboat 9 Pro and above] Advanced > Preflight [Keyboard Shortcut Shift + Ctrl + X ] Have a look at this video to see what I mean: http://www.mattbeals.com/videos/Adobe/ShowImageRes/ShowImageRes.html There are also other plugins and stuff, but as ...


3

PPI means "pixels per inch," and is a web display measurement. DPI means "dots per inch," and is a print measurement. If your Image Size dialog box reads "300 pixels per inch," you're fine. However, if you're starting at less than that, most likely you cannot arbitrarily make the PPI larger without sacrificing quality. (Depends on how far you're sampling ...


3

You figured it out. The dimensions you see in Bridge for the PDF are the output dimensions in points, not the image size in pixels. This is a sometimes misleading side effect of the fact that PDF is (in theory) resolution-independent, much as an Illustrator or EPS document is, that the "dimensions" of the PDF shown in Bridge are the print dimensions, not ...



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