Low quality images make your finished print product appear unprofessional. There are several issues to look for when checking image quality, any of the bad quality image examples below can be printed, however they will not appear professional. For the examples below, we will use this image to demonstrate the different image quality issues.
1. Low Resolution
As you can see in the image above, the image resolution is not high enough to appear clear.
We recommend all images be 300PPI (pixels per inch) at 100% – without upscaling. Images taken from the internet (such as Google search and Facebook) are generally not high enough quality for print. Most web pages use images at 72 PPI, but for high quality printing we recommend 300 PPI or higher. Below 220 PPI pixelation in an image may be visible; below 150 PPI pixelation is very visible.
To resolve this issue – we recommend only sourcing and using high quality images from photographers, or stock photography websites. There is not much that can be done to fix images that are low resolution, the physical size of the image can be reduced on the design, or the image can be up-scaled (to appear as per the up-scaled image below) so that pixelation is not visible, however the image is still not good quality.
See: Is my image high enough resolution?
Artefacts generally appear when image data is compressed too much. When you zoom-in and view detail in the image, you will see jagged edges, uneven colour or extra "noise" in the image (generally along the edges of objects in the image).
JPEG (and other web file formats) compress image data when saved to reduce the file size – which is great for web and email; but not for print. When the file is compressed, these "artifacts" are a result. To resolve this issue, we recommend sourcing the high-quality original files from your photographer (or stock photography website). The only other solution to this issue is to blur the image to remove some of the artefacts – however this does not increase the clarity of the image as seen in the blurry image below.
3. Up-scaled, Blurry or Unclear
To resolve issues with low resolution, artefacts or other poor image quality issues, sometimes the image is blurred out to hide the issues. It can also be caused by a lens not being focused when taking the photograph. As you can see the above image, even though there is no pixelation, the image will not print clear or crisp.
4. Scanned Images
Scanned images and layouts are generally not suitable for printing as they are not high enough quality – it is the same as a photocopy of a photocopy, it will not appear crisp and sharp as the original.