Need help with 16x20 poster conversion from a 4x6 photograph

[Dracogem]

Specifically from a photo that was scanned and saved in jpeg format? I have a terminally ill family member whose wife wants a 4x6 photograph to be enlarged to a 16x20 poster. I worry about distortions due to excessive enlargement. The money is limited and Costco appears to have a great service for specialized photo requests but I'm uncertain that there any trained employees to help with the enlargement to be successful and have excellent quality considering the customer inputs the entire order through a computer and uploads photo from either memory card or from online photo sites no physical scanners that I know of so taking in the physical photo won't help. I want this to be perfect since it will be memorial picture, but with it being trying times I can't spend a great deal of money and wouldn't want to waste loads of with repetitive unsuccessful professional-grade posters.

 

[Edsport]

I'm pretty sure you'll end up with a very poor quality and a 4x6 is not the same dimensions as 16x20. It's the same as 16x24 and also the same as 12x18...

 

[Helen B]

Can you tell us about the existing scan? How many pixels, how large a file?

If it is scanned well at about 600 spi on a decent scanner, and the scan is saved in a high quality JPEG or TIFF, then it is quite possible. It could also be rephotographed by someone with a good camera. Although it won't be very sharp or very detailed, it will be OK for viewing from a distance if the original is OK. A lot depends on the original print, of course.

Where are you? If you don't know anyone who can rescan this for you do you know anyone with a fairly good camera - even a good little Point-and-shoot?

 

[DiskoJoe]

Upload the picture here and someone is bound to help you.

 

[The_Traveler]

Upload the picture here and someone is bound to help you.

But she would be scanning with a comsumer grade scanner.
She probably would get better results from a lab doing high grade scans.