DESCRIPTION:

Indesign could offer the option of upsampling images to a specified PPI on PDF export. Rather than requiring the user to find each under-res image and manually destructively upsample each with a round-trip through Photoshop.

Optimally, there could be a threshold setting below which an image resolution is too low. This could be either "effective" resolution PPI number threshold ("Upsample images with an effective placed resolution above 120ppi"), or a max scale percentage that would be needed to get the image up to the set output resolution ("Upsample images within 40% of target resolution." or "Upsample images by no more than 250%.")

Export dialog could offer different options for dealing with grossly undre-res images or a global "low-resolution" preferences could be set to throw an error at the initial export command similarly to how it deals with missing or modified links.

I understand that the Preflight panel is already designed to manage resolution issues. But I'm suggesting the option of a workflow where image upsampling happens only for a specific individual PDF output rather than permanently modifying linked source images.

REASON:

1. It can be time-consuming to review and override each error that a slightly under-resolution image will throw with modern highly-automated print workflows. (I mean, come on, can anyone see the difference between 280 and 300 ppi once printed? Of course not, but the press doesn't want the liability so throws automated errors if any image is even just 1% under the target resolution.)

2. Sometimes it's necessary to use images that are not available at any additional resolution and require resampling to choose softness over pixelation. But it can be a nuisance to manage the multiple up-sampled assets hanging around after various uses ("Oh look! Here's a higher resolution version! Dangit, nope, it's just another upsample.") A source image would preferably remain at the actual original resolution since in most cases an upsampled image is made for a specific output.