Starting with a photograph, you can never get an image any better than the paper photograph. You can do some processing such as maybe sharpen or color correct in a Photo editor, but nothing you do can be better than that original picture.
IF you had access to the film negative, you can scan the film and get a better image. Film has greater resolution than any print or photograph.
Longedge, you are correct if you are going for 4K, 1920x1080 is not near enough. I doubt that you can get a good image from a 6x4 photograph that would look good in 4K. A paper photograph only has about 300 DPI of resolution, because of the paper process.
This message was edited 1 time. Last update was at Apr 24. 2016 12:26
Carl312: Windows 10 64-bit 8 GB RAM,AMD Phenom II X4 965 3.4 GHz,ATI Radeon HD 5770 1GB,240GB SSD,two 1TB HDs.