app.py

from flax.jax_utils import replicate
from jax import pmap
from flax.training.common_utils import shard
import jax
import jax.numpy as jnp

from pathlib import Path
from PIL import Image
import numpy as np

from diffusers import FlaxStableDiffusionPipeline


import os
if 'TPU_NAME' in os.environ:
    import requests
    if 'TPU_DRIVER_MODE' not in globals():
        url = 'http:' + os.environ['TPU_NAME'].split(':')[1] + ':8475/requestversion/tpu_driver_nightly'
        resp = requests.post(url)
        TPU_DRIVER_MODE = 1


    from jax.config import config
    config.FLAGS.jax_xla_backend = "tpu_driver"
    config.FLAGS.jax_backend_target = os.environ['TPU_NAME']
    print('Registered TPU:', config.FLAGS.jax_backend_target)
else:
    print('No TPU detected. Can be changed under "Runtime/Change runtime type".')

import jax
jax.local_devices()
num_devices = jax.device_count()
device_type = jax.devices()[0].device_kind

print(f"Found {num_devices} JAX devices of type {device_type}.")

def sd2_inference(pipeline, prompts, params, seed = 42, num_inference_steps = 50 ):
    prng_seed = jax.random.PRNGKey(seed)
    prompt_ids = pipeline.prepare_inputs(prompts)
    params = replicate(params)
    prng_seed = jax.random.split(prng_seed, jax.device_count())
    prompt_ids = shard(prompt_ids)
    images = pipeline(prompt_ids, params, prng_seed, num_inference_steps, jit=True).images
    images = images.reshape((images.shape[0] * images.shape[1], ) + images.shape[-3:])
    images = pipeline.numpy_to_pil(images)
    return images
def image_grid(imgs, rows, cols, down_sample = 1 ):
    w,h = imgs[0].size
    grid = Image.new('RGB', size=(cols*w, rows*h))
    for i, img in enumerate(imgs): grid.paste(img, box=(i%cols*w, i//cols*h))
    grid = grid.resize( (grid.size[0]//down_sample, grid.size[1]//down_sample) )
    return grid


HF_ACCESS_TOKEN = os.environ["HFAUTH"]

# Load Model
# - Reference: https://github.com/huggingface/diffusers/blob/main/README.md
pipeline, params = FlaxStableDiffusionPipeline.from_pretrained(
    "CompVis/stable-diffusion-v1-4",
    use_auth_token = HF_ACCESS_TOKEN,
    revision="bf16",
    dtype=jnp.bfloat16,
)