The Short Version
Save your photos at home at full resolution with 100% for best archive quality.
Save a copy of your photos for the album at about 1500 x 2100 pixels with JPEG set at 100%. Using Google Picassa, the Recommended size is 1600 which is perfect.
Image Resolution
Lets talk about how image resolution works for viewing photos on the screen versus printing them.
Computer monitors typically operate between 72 and 100 dots per inch (dpi).
Color printing needs a minimum of 300 dpi to look nice.
So photo on the screen of 1200 x 900 would look great, but you could only print it to a size of 4"x3".
Here are some photo pixel sizes for different size prints:
3x5 = 900 x 1500
4x6 = 1200 x 1800
5x7 = 1500 x 2100
8x10 = 2400 x 3000
Image file formats
The other thing that affect image quality is the file format. There are a couple to choose from:
RAW - Bitmap - nonlossy format - very large files
BMP - Bitmap - Typically uncompressed format, non lossy
PNG - Portable Network Graphics -
GIF - Graphic Interchange Format - typically used for screen graphics. Limited color map and provide transparency (alpha channel) and animation. Not compressed.
JPEG (or JPG) - Joint Photo Expert Group - Adjustable Lossy compression from 100% quality to typically 85% qualify before it gets ugly.
Read more about it here.
http://www.photoshopessentials.com/essentials/image-quality/
