For custom print orders we handle all the image preparation, color correction, proofing, and printing. Simply upload us your camera's raw file. If you didn't take the picture as a raw file, send us the original (unedited) file. It is usually a jpeg or tiff file.
Don't change the image resolution or file size. If you've edited the file on your end for color, done retouching or compositing, or other file manipulation, please send a TIFF file of the edited file, in addition to the raw file.
Do not change the file size or dimensions - please send the file at its native resolution (i.e. as the camera captured it). If you need to export it from Lightroom, follow instructions here.
Send the file to us using our large file upload page. Select "Custom Printing". Then follow the upload instructions on the following WeTransfer page.