Ooops. I have set an improper date on my digital camera and now, Picassa shows my pictures in improper order. I take care of setting the date and time stamp of the file but even though, Picassa puts my new pictures amont the last year ones.
I started searching for a tool that would allow me to change the internal jpeg (jpg) date and time stamps, and I have run onto a very nice one - file Tweak (http://filetweak.com) The sad part this tool, being really an excellent Windows addition to the file properties dialog box, cost money, and I didn't want to spend money to, from time to time, fixing my mistakes. (You can download a limited in time and functionality filetweak from them.)
I have decided to take a closer look to the jpg file and check if I can change the date and time opening the file in binary mode (I use Visual Studio, but you can find other free tools that can do it for you.)
What a surprize - the date time is stored in DOS open format!
Example: 2008:05:25 22:36:40
In my jpeg files are three dates (when the picture has been taken, when was digitalized and when was modified.)
The easiest way then, to change the timestamp of your jpeg files is:
Search for the year your picture has been taken (Right-click on the file, Properties,Summary tab,Make sure Advanced button is on, Search for Date Picture Taken.)
Simply, using any binary editor, modify the date and/or time of the jpg files (up to three places to be changed) and save the file. You're done. Picassa and you will be happy :)