Open the image in IrfanView, and then go to Image Menu > Decrease Color Depth. Here choose "Custom" option, and enter the value (0 to 255) of color depth. And then click "OK" and resave the file.
You have to experiment with the color depth values such that there is no considerable loss in qulaity.
Why always Irfan View. I use Animation Shop. it works great to resize animation. If anybody is having problems post that file to me and I will resize it for you.
Tales Animator is a rather unique tool to create custom cartoon animations in AVI format. It does not require any graphical talent to get started since it includes several of ready-to-use cartoon actors. All you need to do is write a screenplay, using a very easy to understand script language that uses a common English syntax which does not require any programming skills. The program comes with a sample that will get you started immediately, once you look at the documentation and the included sample, you will have no problems understanding the concept. Tales Animator lets you use custom background images (or included scenes) and the characters will speak their text aloud using MS Agent technology to convert your typed text to speech. The result can be saved as a project or rendered to AVI format or exported as animated GIF. This is a unique software with lots of potential. Check it out!