Hot answers tagged dpi
14
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 ...
13
PPI (Pixels Per Inch) settings are not used in web images. Images on the web, retina displays or otherwise, are displayed by their pixel dimensions (width and height) not any PPI/DPI setting. In fact, many web images such as png, gif, jpg may not even store a ppi setting in their internal data and rely on width and height settings.
A 100 pixel x 100 pixel ...
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 ...
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
If you'll be going to a digital print shop to make the posters (which would be usual for a small run for a local event), you'll be fine at 150 ppi, and for a background image you probably wouldn't be in trouble at 100 ppi, particularly since it likely won't contain a lot of high-frequency detail that would conflict with your text.
An 11x17 poster is mostly ...
6
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 ...
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?
5
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 ...
4
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
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 ...
4
Every screen has it's own resolution. Or rather pixel density.
Consider a 20" (diagonal) monitor:
A monitor set to 2560x1600px has a ppi of about 137
A monitor set to 1920x1080px has a ppi of about 102
A monitor set to 1440x900px has a ppi of about 89
I post "about" because actual physical size of the monitor is a factor as well. A 20" monitor with a ...
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 ...
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
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 ...
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 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
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 ...
3
Note that dye-sub is a VERY different printing process than most ink jet or laser printers (and offset printing, for that matter).
In all those other technologies, the color on the page is created from a mix of 4 different colored dots...CMYK.
Dye-sub, on the other hand, has each individual printer dot its own color. That makes Dye-sub a true continuous ...
3
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:
...
3
Import the Illustrator file into Photoshop as a Smart Object File > Open As Smart Object.\
Use Image > Resize with "Resample" turned on to change the width to 100cm.
Be prepared to wait a long time, depending on your RAM and scratch disk (operation may fail if your system isn't up to it).
Image > Mode > Greyscale
Image > Mode > Bitmap
Save ...
3
How far away is someone going to be looking at it?
Typically the larger the printer, the further away the user is going to be looking at it, so the lower resolution that you need.
At 4m x 2.5m, that sounds like a small billboard, so anything over 72dpi is likely overkill given that people will be 20 meters away looking at it.
(but, in the end, consult ...
3
You can't control the line screen within Illustrator. That's an output device option and not a creation software option. For example, your home/office printer may have an LPI setting in the print dialog window, but that controls the output device, and does not change the artwork.
DPI = 1.5 x LPI
That means you need a minimum of 225ppi for most presswork. ...
3
You have fundamental lack of understanding about the process and terms.
DPI is dots per inch, and is a derived unit which requires dots and inches to calculate.
For computer images, inches have no meaning, they only exist in the physical world. For images you have dots only, and they are called pixels, which are irreducable. DPI is stored merely as a "flag" ...
2
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. ...
2
As @DA01 answered, DPI on the JPG-files are only meta-information, or instructions for the printer. No matter what you set the DPI, it usually (always) can be overridden by the publishing software. Changing the DPI shouldn't change the file size—if other settings are intact.
If other settings are intact, which they usually aren't when saving a JPG with a ...
2
For a photo being printed on an offset press, the rule of thumb is that you want the resolution of the photo to be twice the dot pitch of the halftone screen. For example, of you have a 150lpi screen then your image should be at least 300dpi at its final size.
Most modern LCD monitors have about 100dpi physical resolution or so.
For web site design you ...
2
First, try to use vectors when you can (especially for print). Vectors have 'infinite' DPI.
When you use bitmap images in your design, try to keep the original DPI and resolution. You can always export the finished product to the desired DPI. For print, this is often 300 DPI, but sometimes more.
When exporting for a web page, you need to know how big the ...
2
Your maths is correct but remember that working at 400 ppi at 1:10 scale will give you 40 ppi final output, which sounds in the right sort of area for billboard printing, bearing in mind the distances they are generally viewed from.
I think you'll have a problem of sourcing images much bigger than 5000 px x 5000 px image, which is 25 megapixels.
But this ...
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