This warning is given by our Prepress team if one or more images in your artwork appear to be low resolution/quality.
You may proceed with printing your Online PDF proof as is by clicking Approve Proof, however, we recommend re-supplying your artwork with higher quality image/s.
A frequently asked question from customers is: "Can you fix a low res image?"
In most cases, we are not able to correct this. This article will further explain why.
Raster images have a certain amount of pixels within each inch (ppi = pixel per inch or dpi = dots per inch). A 72 ppi image has 72 pixels in every inch, a 300 ppi image has 300 pixels per inch. The higher the ppi, the higher the quality. Jukebox Print requires files with 300 ppi at 100% image size - without upscaling.
That means the file must have been created at both the dimension and the resolution required. For example, if you create a business card in Photoshop, the final image size with bleed needs to be 3.75" x 2.25" at 300 ppi. So it must be created at a minimum of 1125 x 675 ppi (3.75" x 300 ppi and 2.25" x 300 ppi).
Once the image is created at a certain dimension, you will not be able to use this image at a larger size without losing quality. When you manually increase the resolution in Adobe Photoshop, the program randomly adds pixels and the result will be a high-resolution image of poor quality.
This means we are not able to fix the resolution of your image if it has not been created with the proper amount of pixels and at the proper size. You will need to supply a better quality image (if it is only one or two images within your design) or re-create the whole artwork if the file itself is low ppi.
To view and edit image pixel dimension you must use a photo-editing program like Adobe Photoshop or Paint Shop Pro to open the raster file.
See: Image Quality