Upsizing Images

 I started work making a Grand Canyon North Rim calendar at CafePress and immediately ran into problem that some of my images images are a bit low res.  Yes they are 10MP images, but when blown up to wall calendar I was warned of pixilation.  I could go back with my new camera but then I remembered that IrfanView (a really cool, free program) has a Resize function that not only shrinks images down but also interpolates pixels as it resizes upward.

It may not be obvious unless you download the images. 1280x857

Now 3840x2572:

The file sizes are not dramatically different in size because of the magic of JPG's discrete wavelet function.