The best replacement for bitmap is jpeg.

The best alternatives to bitmap are rated as following:
★★★★★  jpeg
★★★★★  vector
★★★  tiff
★★  png
★★  vector graphics
★★  raster
★★  jpg
★  gif
★  jpeg quality
★  metafile
★  vector images
★  vector image
★  jpeg better
★  b tree
★  btree index
★  image c#
  bitmapimage
  enhanced metafile
  btree
  bitmask
  bitmapsource
  bitmapdrawable
  grayscale
  picture
  b-tree
  device independent bitmap
  vector animation
  tif
  vectors
  drawable
  vector graphic

Your alternative for bitmap is not listed? Suggest!
Speaking about bitmap, one probably shouldn't forget about 8 bits per pixel.

Other search terms related to bitmap and their ratings are:
★★★★★ 8 bits per pixel
You have in mind a companion for bitmap and it is not yet here? Propose!



Google Trends

Scale is based on the average worldwide traffic of bitmap in all years. Click on graph for more.
bitmap
jpeg
vector