default_fields_binary.py

import base64
from odoo import tools


@api.model
def _default_image(self):
    image_path = get_module_resource('hr', 'static/src/img', 'default_image.png')
    return tools.image_resize_image_big(base64.b64encode(open(image_path, 'rb').read()))

image = fields.Binary(
    "Photo", default=_default_image, attachment=True,
    help="This field holds the image used as photo for the employee, limited to 1024x1024px.")