Upsampling an image?!?!?

[Colin_da_Killer]

Hi all,

Getting 6 photos of mine printed at 30" x 20" on the photobox special offer.

1 of the image won't be a problem resolution wise or quality wise as I shot it in RAW, the others however are 2584 x 3458 jpg's but under 1mb in size. Is this a huge problem? One of them is only 1944 x 2592 and 800kb!!!

Can anyone recommend the best way to upsample these images for such large poster prints???

Thanks a lot.
Colin.

 

[Colin_da_Killer]

What rating do they get as standard?

In photobox, they get green, 2bars from full, except for the bottom resolution photo which is orange and 4 bars from full.