Photography question: converting low-res to hi-res

Earlier in the year I worked on a project where a photographer provided a number of photos (mostly indoor) - about 40 or so were selected from 700-1,000 or so, the photographer converted the 40 images to hi-res, and they were used in a print publication.

Now the client wants to convert the files (700-1,000 images) to hi-res so they can load onto their website, to be viewed as websites are viewed (from desktop, laptop, mobile). They have the contractual rights to do this, but they don't want to use the low-res images.

Is the process of converting to hi-res lengthy and complicated? Can someone other than the original photograher do the work? They want to avoid going back to the photographer for more work as he has a high hourly rate, he might not be available, all that. Thanks for any input.

You cannot convert files from lo-res to hi-res. What the photographer did for the 40 selected images was go back to his original image files and make hi-res images for your client to use. The information you need to make a hi-res image is not retained when a lo-res image is made, that is what made it a lo-res image.. The only way to get it is from the original file, or from a higher resolution file made from the original image.

Yup...what max said.

Correct. Cannot make hi rez from low rez.

Point of reference: for the uses you listed, all you'll need are the low rez.

Thanks, all. Good point, I suspected low res is fine, particularly for people accessing this stuff from a mobile device.

What size are the low res images and how much larger do they need to be? If you're going from 200px wide and want 1000px wide, then that's not possible. If it's in the range of going from about 700px to 1000px, there are some Photoshop tricks using bicubic smooth sampling and sharpening that can result in decent enlargements. Best thing to do is to get the original high res images, of course.

Actually what probably happened is the photog shot in a raw (file format) and then converted it to a hi rez jpg for print. I would ask the photog for hi rez jpgs of the remaining files - if that's in the contract.

I concur. Was just typing what joy was describing.