No need to do anything different when uploading photos to Picasa. Just do it as you normally would. The trick is in linking them.
Compare the below two below links carefully.
引言回覆:
http://lh6.ggpht.com/_3oWmXWJSSio/ShyiYlDPprI/AAAAAAAAFYM/1XSy2D58iTY/s912/_DSC0041-psed.jpg
引言回覆:
http://lh6.ggpht.com/_3oWmXWJSSio/ShyiYlDPprI/AAAAAAAAFYM/1XSy2D58iTY/s640/_DSC0041-psed.jpg
They are basically the same except for the size specified. First one is s912 and second one is s640. What I did was simply change the s912 to s640 and leave rest of the link untouched. S912 means 912px wide and s640 means 640px wide. Once you specify the width, Picasa will automatically choose a height when the photo is shown through the link. In my experience, I found that s640 or s720 seem to be the best width when linking photos from Picasa web albums. Anything other than s640 or s720 often have a hard time showing up.