Prepare your files for the best printing results!
PosterBox wants to help you create the best poster printing files, so we can print you high quality posters that'll make you go wow!
Handy tips on getting your posters looking great:
- Image Resolution
- Poster Sizes
- Pixels and Vectors
- Page Size (poster size)
- Creating a great PDF file
Set your document to the correct poster size
One of the more overlooked aspects of poster design is correct poster/pager size. Setting your document to the correct poster/page size will help you while designing and eliminates size confusion when printing. In most programs, such as Word, Publisher, Powerpoint etc, the Page Size can be set in Page Setup usually located in the File menu. Take your time and explore your options and set your page to the poster size you want. You can use standard sizes such as A2, A1 and A0 or it is sometimes possible to create a custom poster size. Non standard but common poster sizes include 750 x 1000 for shopping centre display and 600 x 900mm for sidewalk stands.
Now that you have your poster set at the correct size when you place/import your images you will see their 'true' size. The more you enlarge your images the lower the print quality of your images. Try to avoid enlarging your images by more than 300%.
If your poster has not been designed at the correct size, don't panic, PosterBox can still print your posters. When ordering just ask us to enlarge your poster to the correct size. We can only enlarge your poster proportionally.
- A2 Posters - 594mm x 420mm
- A1 Posters - 840mm x 594mm
- A0 Posters - 1,188mm x 840mm
- B0 Posters - 1,414 x 1,000mm
- B1 Posters - 1,000mm x 707mm
- B2 Posters - 707mm x 500mm
Pixels and Vectors
And why is it important to understand the difference.
The key difference between pixel and vector based graphics is how the image is structured.
Pixel based graphics are made up from lots of tiny physical squares (or ‘pixels’)
Vector graphics are mapped out using mathematical equations which calculate where the edges of the shapes sit in relation to one another.
As an example; fonts are always created using vectors so that the colours can be changed efficiently and the symbol can be easily scaled up to any size without losing quality. In contrast, digital photographs are always made up of pixels.
A raster graphic is an image made of hundreds (or thousands or millions) of tiny squares of colour information, referred to as either pixels or dots.
Pros of Raster Images
Rich Detail: Ever wondered what the term “dpi” stands for? It means “dots per inch,” a measurement of how much detailed colour information a raster image contains. Say you’ve got a 1” x 1” square image at 300 dpi—that’s 300 individual squares of colour that provide precise shading and detail in your photograph. The more dpi your image contains, the more subtle details will be noticeable.
Precise Editing: All of those individual pixels of colour information can also be modified, one by one. So if you’re a true perfectionist, the level of editing and customization available in a raster image is almost limitless.
Cons of Raster Images
Blurry When Enlarged: The biggest downfall to raster images is that they become pixelated (aka grainy) when enlarged. Why is this? Well, there are a finite number of pixels in all raster images; when you enlarge a photo, the computer takes its best guess as to what specific colors should fill in the gaps. This interpolation of data causes the image to appear blurry since the computer has no way of knowing the exact shade of colours that should be inserted.
Large File Size: Remember how a 1” x 1” square at 300 dpi will have 300 individual points of colour information for the computer to remember? Well let’s say you have an 18” x 24” photo— that’s 129,600 bits of info for a computer to process which can quickly slow down even the fastest machine.
A vector graphic uses math to draw shapes using points, lines and curves. So whereas a raster image of a 1” x 1” square at 300 dpi will have 300 individuals pieces of information, a vector image will only contain four points, one for each corner; the computer will uses math to “connect the dots” and fill in all of the missing information.
Popular vector file format extensions include: eps, ai and pdf.
Pros of Vector Images
Infinitely Scalable: Through the wonders of math (which I don’t claim to understand), vector files can be scaled up or down as much as you want without losing any image quality. Whereas a raster image must guess the colors of missing pixels when sizing up, a vector image simply uses the original mathematic equation to create a consistent shape every time.
Smaller File Size: Using our previous 1” x 1” square example, a vector file needs only four points of data to recreate a square versus 300 individual pixels for a raster image. For simple graphics, like geometric shapes or typography, this means a much smaller file size and faster processing speed.Edibility: Unlike popular raster-based formats, such as a jpg or png, vector files are not “flattened.” When you open them back up in a program such as Adobe Illustrator, all of the original shapes exist separately on different layers; this means you can modify individual elements without affecting other objects in the image
Colours to be CMYK and process
Your monitor, unless it is well calibrated, is unlikely to be able to produce a 100% accurate representation of the colours you have used in your poster design when printed. A quick overview of Colour Theory well help to explain why.
The colour that you see on a monitor is created using light projected, or additive colour model; whereas the colour created by a printed document is reflected light–the subtractive model.
When designing a poster you use a monitor which uses the additive colour model (Red Green Blue) to create the colour you see on screen. When printing the subtractive colour model (Cyan Magenta Yellow K Black) is used. The difference in the two models is highlighted by these images. When pure red, green and blue are added together in equal strength, white is created. Conversely when Cyan, Magenta and Yellow are mixed black is created–well a dark grey–and this is why printers use K (black) in printing. Colour can easily be taken for granted but if you were to investigate colour you would find countless years/decades of research and development, and that's just in the printing industry, all to make sure colours print consistently
So while the colour you have chosen looks great on the screen, eg a bright blue, it may not print as bright as you see it on your screen. It will still print blue but maybe just a little different to the blue you see on screen. Use your monitor as a guide only.
Graphic designers and clients who use software such as InDesign, Illustrator, Quark etc, colours in CMYK with all colours converted to process. If you have designed your entire poster in Photoshop, or require photos to be enlarged you may leave the file(s) in RGB.
Interested in more information on Colour Theory?
PosterBox uses the latest in poster printing technology to produce the best possible results from the files you supply.
Images and Graphics
PosterBox recommends a minimum of 150dpi at print size for all images.
A great image can make your poster design leap out at your audience. An image that looks great on screen though may not print as well as you hoped if it isn't the right resolution. Print resolution is referred to as DPI - Dots Per Inch. There are 2 factors to consider when checking the resolution of your images:
- the measurements of the image; that is, if printed at 100%, what size is the image?
- the DPI of the image
Why is this is important?
If you have an image who's measurements are 10 x 15cm at 300dpi, if you were to use this image and then enlarge it your design to 30 x 45cm the image when printed would be at 100dpi. Conversely, if you have an image at 72dpi (which is far too low for printing) which measured 1mtr x 60cm and you reduced the size of the image to 50 x 30cm the print resolution would be 144dpi. So you can see you need to know both the dpi and measurements of your image to make an informed decision about your images.
The ideal printing resolution for images is 300dpi at the size they are being printed, however with continued improvement in prepress processing images at 150dpi print nearly as well. PosterBox recommends minimum 150dpi at print size. Where possible images should be converted to CMYK.
If you are able to know both the dimensions and print resolution you will have a better idea of how well your images will print. Adobe Photoshop and similar programs can tell you your image's size and dpi. Want more info on image quality?
For the best possible poster prints, we need you to supply your design files as a PDF.
If you don't have your artwork in PDF, see our handy creating print ready PDFs guide.