iTerm2 version 3 beta has an option to pass image data in an escape sequence

iterm2_inline_images.fish

# this works in Fish, prob works in Bash too, I didn't try it
# you'll probably need to install the chunky_png gem: `gem install chunky_png`
# docs:  http://iterm2.com/documentation-images.html
# video: https://vimeo.com/170123782

ruby -r chunky_png -r base64 -e '
   radius          = 100
   num_points      = 200
   magnitude_delta = 0.1
   white           = ChunkyPNG::Color.rgb 0xFF, 0xFF, 0xFF
   clear           = ChunkyPNG::Color.rgba 0xFF, 0x00, 0x00, 0x00
   to_radians      = -> point   { 2*Math::PI * point/num_points }
   to_x            = -> radians { Integer radius+radius*Math.cos(radians) }
   to_y            = -> radians { Integer radius+radius*Math.sin(radians) }
   display_image   = -> b64img  { "\e]1337;File=preserveAspectRatio=1;inline=1:#{b64img}\a" }
   save_cursor     = "\e[s"
   restore_cursor  = "\e[u"

   # Use C-c to kill it
   magnitude = 1
   1.upto Float::INFINITY do
     canvas = ChunkyPNG::Canvas.new 2*radius, 2*radius, clear
     1.upto num_points do |point|
       start    = to_radians[point]
       finish   = to_radians[point*magnitude]
       canvas.line to_x[start],to_y[start], to_x[finish],to_y[finish], white
     end
     img_data = Base64.encode64 canvas.to_blob(fast_rgba: true)
     print "#{save_cursor}#{display_image[img_data]}#{"%0.2f"%magnitude}#{restore_cursor}"
     magnitude += magnitude_delta
   end'