Convert the bitmap image into a symbol if it appears in more than one keyframe. Try tracing and simplifying the bitmap when appropriate. This works best with simple images made up of mostly large blocks of color. If the bitmap contains complex shapes and many colors, the converted vector graphic can have a larger file size than the original bitmap. Try a variety of settings in the Trace Bitmap dialog box to find a balance between file size and image quality.
Compression helps reduce the total file space occupied by bitmap images.
JPEG compression is the default compression for all bitmap images exported to Flash Player format. Because JPEG compression can result in a loss of image data, test images with different JPEG quality values to achieve the best balance between compression and image quality for your particular movie. Bitmap images may also be exported with lossless compression to retain image quality. Lossless compression, however, cannot achieve as great a reduction in data size as JPEG compression. Generally, lossless compression is appropriate for non-photographic bitmaps with simple shapes and relatively few colors.