I didn't recall the abiltiy to select dpi in my Save As.
My first showing is tonight and my goal is to have people order the photo either mounted, or fully framed.
You can set the dpi and inches by creating a custom export preset, when exporting the version:
- Select File > Export > Version and set the "Export Preset" to "Edit".
- Press "+" to add a new preset, name it.
- Then set "Size to" to "Fit within Inches"; if you are unsure, set both values identical to the largest value.
- Set the dpi.
Then export using the new preset.
Would simply saving in a TIFF format and re-uploading the images which number in the hundreds, solve the issue?
Not really. The issue at heart isn't PPI, but the information density, of which PPI is a proxy measurement. You could create a bigger file from the same information (the file created by your camera when it recorded the pattern of light hitting the sensor during the time the shutter was open) that would have higher PPI, but it would not contain any more information. The printer needs more information to print larger while retaining the image quality. Stretching the same amount of information across a larger area degrades the quality.
The reply from the website host is spot-on. 100 PPI (Pixels per inch; Dots per inch is sometimes used, erroneously) is a good working minimum for a print that looks OK at reading distance. As suggested, it really is a minimum -- you are well advised to provide any printer with about 250 PPI for "sharp" prints.
To make sharp 20 x 30 inch prints (one you can walk up to and examine detail) you need 4,000 x 6,000 pixels or more (20 inches x 200 pixels per inch = 4,000 pixels).
These are guidelines. The actual PPI needed will depend on other quality factors and the viewing environment (billboards look sharp at about 6 PPI).