Photoshop CS3 is not the latest version of the application but is definitely one of the more advanced. It has a feature which you can use to employ a limited amount of animation on an image. One simple sequence is to make an object in an image disappear.
1. Place the object into a separate layer.
You will be actually using two images. One will serve as the background and the other will be the foreground containing the specific object you want to fade out. You will need to prepare the foreground image making sure that it contains no other pixels but those of the object. You might need to use the Marquee or Lasso tool for outlining and selecting the object and the Eraser tool as well for removing any irrelevant background or visual elements. Make sure background and foreground/object images are in their own respective layers. When both layers are enabled to be visible on the Layers palette, you should see only one composite image on the main window.
2. Use the animation palette.
Activate this feature by clicking on the Window menu and then on the Animation option. The animation palette will appear and this will contain a timeline where you will build a sequence of frames. The composite image should appear on the first frame. Select this frame and then click on the button labeled 'Duplicate Selected Frame'. This action will make a copy of the composite image and place it in a second frame.
3. Make the object transparent.
Select the second frame then return to the Layers palette. Select the layer containing the foreground/object image. Right-click on this layer and access Layer properties. On the properties dialogue box that will appear set the Transparency to zero. Check the animation palette; only the background layer should be visible on the second frame.
4. Set the sequence of frames.
With just two frames, the object will disappear in a blink. If you want it to fade out gradually you can set 'tweens' or in-between frames. Click on the Tween button and the Tween dialogue box will appear. Pull out the 'Tween With:' option's drop down list and choose 'Previous Frame'. On the 'Frames to Add:' input box, you can enter any number depending on how gradual you want the fade out to happen. It is recommended that you place only a few in-between frames, about 3 to 5, to make the file light and easy to load. Since were animating an object's disappearance, the 'Opacity' item under Parameters should be checked.
5. Save the file in GIF format.
Check the timeline on the animations palette. It should now have a sequence of frames beginning with an image of the solid object with background and ending with only the background image. With everything in place, you can now save this file in GIF format to make it an animated GIF. Among the various save options under the File menu, choose 'Save for Web and Devices'.
Animated GIFs are now quite commonplace on the Web. You'll see them as avatars, banner ads or clickable buttons on a website. Before Photoshop CS3, one had to actually use animation programs in combination with image editing software to make simple animated GIFs.