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Resolution Guide

20/10/2015 16:24:57


Resolution Guide

A common issue with printing can be pixelation, a term used when images look blocky. This guide should help you to understand the concept of resolution for printing and what exactly dpi or ddi mean.

In This Guide
From here you should be able to jump to the correct section for fixing your document. Please note that this guide explains how to fix many different document formats, only one of which will be applicable to your case. (Please note – this is a simplified guide and not a technical explanation). This guide will cover the following areas.

  • Basic explanatation of resolution and why we require high resolution documents for printing
  • How to check the resolution of a document
  • How to create high resolution documents from commonly used software

1.) Basic Explanation of Resolution
One of the questions we are commonly asked is “it looks fine on screen, why won’t it be ok to print?”. The technical answer to this is that a screen will only display a document at 72dpi where when printed you will see 300dpi. dpi (or ppi) stands for dots per inch or pixels per inch. Generally images and graphics are made up from small dots (pixels), dpi refers to the number of these dots per inch. An image made from dots is called a raster image. There is another format called vectors, these are graphics made from equations and will never distort at any size.

Example
While it’s not particularly easy to show the differences online, below is an example of the same body of text saved at 72dpi and 300dpi resolution and then scaled to the same height. As you’ll see on the left example this has required upscaling which has resulted in pixelation. 

72v300.jpg

Looking at the example above it is possible to see that the 72dpi text (left hand side) will appear distorted when printed where the 300dpi example will appear clear. The distortion on the 72dpi text is called pixelation. It is technically impossible to increase the resolution of an image – to improve it you will need to go back to the software that you have used to create the design.

2.) How to Check the Resolution of a Document
The simplest and quickest way to check the resolution of a document is to view the image on a screen at three to four times the final size that it will be printed. When viewing a pdf if you zoom into 300-400% this should give a good idea of the level of detail visible when printed. The reason for this is that a screen will display the image at 72-100dpi where when printed you will be able to see upto 300dpi. (Why not test this rule on the text above?) 300 dots / pixels per inch is equivalent to 118 pixels per centimetre. Using this we are able to determine the correct dimensions for a document in pixels.

Size Name Size in cm
(without bleed area)
Size in pixels 300dpi
(without bleed area)
Size in cm
(with bleed area)
Size in pixels 300dpi
(with bleed area)
Business Card 8.5 x 5.5 cm 1004 x 650 9.1 x 6.1 cm 1075 x 720
DL / Comp Slip 9.9 x 21.0 cm 1169 x 2480 10.5 x 21.6 cm 1240 x 2551
A6 14.8 x 10.5 cm 1748 x 1240 15.4 x 11.1 cm 1819 x 1311
A5 21.0 x 14.8 cm 2480 x 1748 21.6 x 15.4 cm 2551 x 1819
A4 29.7 x 21.0 cm 3508 x 2480 30.3 x 21.6 cm 3579 x 2551
A3 42.0 x 29.7 cm 4961 x 3605 42.6 x 30.3 cm 5031 x 3579
A2 59.4 x 42.0 cm 7016 x 4961 60.0 x 42.6 cm 7087 x 5031
A1 84.1 x 59.4 cm 9933 x 7016 84.7 x 60.0 cm 10004 x 7087
A0 118.9 x 84.1 cm 14043 x 9933 119.5 x 84.7 cm 14114 x 10004

The table above is based on printing a portrait document at 300 pixels per inch which will give a high quality result. When measuring a digital image there is no defined size in cm or inches, this is determined by the dpi. For example an image that is 1748 x 1240 pixels would be A6 size at 300dpi or A4 size at 150dpi. (An A4 document is twice the height and twice the width of an A6)

3.) How to Create High Resolution Documents (or Fix Documents)
Normally a document will fit into one of three categories. By using the 400% rule of thumb you should be able to identify which category your document fits into.

3.1) Certain Parts of the Document Are Low Resolution

Replace: The best solution is to replace the offending logos / picture with one that is a higher resolution or vectored. If you're looking for better resolution logo files good places to check are; your web designer, any old proofs from printers and electronic versions of corporate documents that have been professionally produced. High quality photos can be purchased from stock photography websites such as iStockphoto or Shutterstock.

Re-size: By making a picture or logo smaller you can reduce pixelation. Use the 4 x rule of thumb to check.

Rebuild: This is by far the most complex & expensive option, pictures unfortunately cannot normally be rebuilt. With logos it is often possible to rebuild, however it is notoriously expensive as it requires a lot of design time. If this is your only option we will be happy to provide a quote.

3.2) Part of the Document Is Vectored and the Rest Is Low Resolution

This problem suggests that the settings in the software that you have used to create the document are incorrect and are reducing the quality of the document content when saving as a jpeg or pdf. Common examples of this are having the export settings in an indesign document incorrectly configured or saving directly to a pdf from a word document.

Solution: Generally this problem can be solved simply by changing the options given when saving to a pdf or jpg image. The resolution options should always be set to a minimum of 300dpi and if you care given compression options these should be set to maximum. If you are unsure of where you can find these settings please refer to the pages further down this document where screen shots of commonly used software settings can be found. If when checking the images in your chosen design software using the 4 zoom rule of thumb the images appear to be low resolution refer to the previous section in this document “certain parts of the document are low resolution”

3.3) The Whole Document Is Low Resolution
This problem can be caused by a variety of reasons which will normally depend on the software that you have used to create the file. This sections will be broken down into the common software used to create the print files and will show screen shots of each type. If the software you are using is not listed in this section it may still be worth reading as several settings are common. Examples gifs show setting up an A5 landscape flyer with 3mm bleed and then exporting as a print ready pdf.

Resolution Guide: InDesign

resolutionguideindesign.gif

Resolution Guide; Photoshop

resolutionguidesphotoshop.gif

Resolution Guide: Illustrator

resolutionguidesillustrator.gif

4.) Frequently Asked Questions

Q: Can instantprint improve the resolution of my design?
A: No, technically this is not possible, this will have to be done in the design software that you have used to create the design.

Q: I can’t improve the resolution of my design what can I do?
A: There are two main options. You could either pay to have a new design professionally made or or could print the document “as is”. We would not recommend printing a document below 300dpi for the reasons outlined in this document.

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