import bpy
from bpy_extras.object_utils import world_to_camera_view

hand_pose = bpy.data.objects["Armature"].pose;

render_scale=bpy.context.scene.render.resolution_percentage/100;

height = 512
width = 512

bpy.context.scene.render.resolution_x = width
bpy.context.scene.render.resolution_y = height
bpy.context.scene.render.resolution_percentage = 100

render_size = (
    bpy.context.scene.render.resolution_x * render_scale,
    bpy.context.scene.render.resolution_y * render_scale
    )

bpy.context.scene.render.filepath = 'sample.png'
bpy.ops.render.render(write_still=True)

fingers=[ 'finger_pinky.03.L', 'finger_ring.03.L', 'finger_middle.03.L', 'finger_index.03.L', 'thumb.03.L' ]

for i, finger in enumerate(fingers):
    pos = world_to_camera_view(bpy.context.scene,     bpy.context.scene.camera, hand_pose.bones[finger].head)
    print(finger + ' position is ', render_size[0]*pos.x, height-render_size[1]*pos.y-1)

finger_pinky.03.L position is  255.89732360839844 297.16163635253906
finger_ring.03.L position is  249.3601531982422 292.98570251464844
finger_middle.03.L position is  246.95179748535156 286.85406494140625
finger_index.03.L position is  249.28578186035156 279.54920959472656
thumb.03.L position is  266.2782287597656 270.7700500488281

for obj in bpy.data.objects:
  if obj.type == "MESH":
    for v in obj.data.vertices:
      co = obj.matrix_world * Vector((v.co.x, v.co.y, v.co.z, 1))
      co = world_to_camera_view(scene, camera, co)