Some photos may not be of a sufficient quality to be printed.
A picture's resolution is crucial if you aim at a good result. For example, we suggest not to use picture downloaded from social networks like SnapChat or Facebook, as often their have a low resolution.
You PC or mobile screen is actually able to show clear-cut images, even though the pictures have a low resolution. However, if you wish to print out those low resolution images on paper, they may result blurred or pixelated.
As a consequence, we advise you to only print high resolution pictures, for example those taken directly with you mobile phone or digital camera. It is equally important to pay attention to the "quality warnings" provided by our website during the creation process.