Is there a way to slice a composition? Like in Photoshop

To create a professional quality animated GIF, it should follow these rules:

1. Frame size is an even number of pixels high and wide
2. Frame rate 12 to 15 fps
3. No duplicate frames - you set the timing of each individual frame in Photoshop or with a professional GIF creation app
4. Colors should be carefully chosen - there are only 256 available
5. Thin horizontal and vertical lines must be perfectly aligned to the pixel grid

If you use After Effects for the basic design, the project should be set to 8-bit color, and you should render a movie using the Render Queue/Output Module Default Hight Quality setting. That movie is imported into Photoshop, and the Motion workspace should be used to finalize the creation of the GIF. If you have not eliminated all duplicate frames in your AE Comp, delete all duplicate frames in the Photoshop timeline, set the timing of the frames you want to pause, then use the File/Export/Save For Web Legacy menu to export your animated GIF.  

You can do your Slicing in Photoshop and export two different gifs there. 

After Effects is not the most efficient tool for creating Animated GIFs, but it can be done and done professionally if you follow those guidelines. I don't do many anymore, but it is possible to create a 30-second looping animated banner that pauses on five different graphics and has a half-second animated transition between the slides that is only 65 frames long. (60 frames for the five transitions and one frame for each of the 6-second graphics )Visually, there is no difference between that efficient GIF and one that is 360 frames at 12 fps or 450 frames at 15 fps.

Thought of a hack- probably can mask it out in photoshop. But if anyone has any tips for how to properly do this. I would love to hear 🙂 

Unfortunately there's no real slicing. You have to duplicate the comp in the project window and then "crop" them by setting a new comp size. The alignment options are on the advanced settings page. Alternatively you can use the limited region and use *Crop to limited region" in the composition menu, but apparently you would have to be very precise doing this on two comps that need to align perfectly.

Mylenium