To ensure print quality of your final product we have implemented quality control parameters for each upload specific to the final size of the printed image. This requires that most of your images meet our 300dpi requirement while also having a minimum pixel length and width based on the dimensions of the final print. Please note that some larger image sizes have lowered dpi parameters since they are often viewed from greater distances and thus require less detail. If you file is producing an error message once the upload has attempted, it is because we cannot ensure that your image will print at a level of quality that you will be happy with. We want to be sure you love your gallery wall and are extremely pleased with your printed images, so we have put these safe guards in place to ensure customer satisfaction. If you would like some useful information about image quality, cell-phone captured images etc. please see our article here for help.