Use Correct File Format
Digitally printed banners and offset printing projects are output in a PDF workflow. Posters can be composed to scale in any professional page layout application before saving/exporting as PDF, one poster for file. Unless otherwise indicated on the worksheet, it is assumed that files are to be output 100 percent (same size). Maximum PDF enlargement is 400% so, if it's more convenient, art can be prepared at one quarter of its final print size; in doing so, resolution of images must also be scaled accordingly, so instead of 150 PPI, 600 is required at minimum.
TIFF (LZW compression), flattened Adobe Photoshop (PSD) or native Illustrator (AI) documents can supplied when ClinicalPosters.com is preparing the layout. Optimum resolution at final print size for large posters is 150 to 240 PPI. For offset printing, 300 PPI is preferred.
With most images originating from digital cameras or stock photography, JPEG files are common. These are acceptable if saved with the highest quality setting. However, since the format actually discards pixel data to achieve file compression every time the file is saved, it is recommended that JPEG images be saved in another format after compositing or color balancing.