mlx-examples/flux/txt2image.py

# Copyright © 2024 Apple Inc.

import argparse

import mlx.core as mx
import mlx.nn as nn
import numpy as np
from PIL import Image
from tqdm import tqdm

from mlx_flux import FluxPipeline


def to_latent_size(image_size):
    h, w = image_size
    h = ((h + 15) // 16) * 16
    w = ((w + 15) // 16) * 16

    if (h, w) != image_size:
        print(
            "Warning: The image dimensions need to be divisible by 16px. "
            f"Changing size to {h}x{w}."
        )

    return (h // 8, w // 8)


def quantization_predicate(name, m):
    return hasattr(m, "to_quantized") and m.weight.shape[1] % 512 == 0


def load_adapter(flux, adapter_file, fuse=False):
    weights, lora_config = mx.load(adapter_file, return_metadata=True)
    rank = int(lora_config["lora_rank"])
    num_blocks = int(lora_config["lora_blocks"])
    flux.linear_to_lora_layers(rank, num_blocks)
    flux.flow.load_weights(list(weights.items()), strict=False)
    if fuse:
        flux.fuse_lora_layers()


if __name__ == "__main__":
    parser = argparse.ArgumentParser(
        description="Generate images from a textual prompt using stable diffusion"
    )
    parser.add_argument("prompt")
    parser.add_argument("--model", choices=["schnell", "dev"], default="schnell")
    parser.add_argument("--n-images", type=int, default=4)
    parser.add_argument(
        "--image-size", type=lambda x: tuple(map(int, x.split("x"))), default=(512, 512)
    )
    parser.add_argument("--steps", type=int)
    parser.add_argument("--guidance", type=float, default=4.0)
    parser.add_argument("--n-rows", type=int, default=1)
    parser.add_argument("--decoding-batch-size", type=int, default=1)
    parser.add_argument("--quantize", "-q", action="store_true")
    parser.add_argument("--preload-models", action="store_true")
    parser.add_argument("--output", default="out.png")
    parser.add_argument("--save-raw", action="store_true")
    parser.add_argument("--seed", type=int)
    parser.add_argument("--verbose", "-v", action="store_true")
    parser.add_argument("--adapter")
    parser.add_argument("--fuse-adapter", action="store_true")
    parser.add_argument("--no-t5-padding", dest="t5_padding", action="store_false")
    args = parser.parse_args()

    # Load the models
    flux = FluxPipeline("flux-" + args.model, t5_padding=args.t5_padding)
    args.steps = args.steps or (50 if args.model == "dev" else 2)

    if args.adapter:
        load_adapter(flux, args.adapter, fuse=args.fuse_adapter)

    if args.quantize:
        nn.quantize(flux.flow, class_predicate=quantization_predicate)
        nn.quantize(flux.t5, class_predicate=quantization_predicate)
        nn.quantize(flux.clip, class_predicate=quantization_predicate)

    if args.preload_models:
        flux.ensure_models_are_loaded()

    # Make the generator
    latent_size = to_latent_size(args.image_size)
    latents = flux.generate_latents(
        args.prompt,
        n_images=args.n_images,
        num_steps=args.steps,
        latent_size=latent_size,
        guidance=args.guidance,
        seed=args.seed,
    )

    # First we get and eval the conditioning
    conditioning = next(latents)
    mx.eval(conditioning)
    peak_mem_conditioning = mx.metal.get_peak_memory() / 1024**3
    mx.metal.reset_peak_memory()

    # The following is not necessary but it may help in memory constrained
    # systems by reusing the memory kept by the text encoders.
    del flux.t5
    del flux.clip

    # Actual denoising loop
    for x_t in tqdm(latents, total=args.steps):
        mx.eval(x_t)

    # The following is not necessary but it may help in memory constrained
    # systems by reusing the memory kept by the flow transformer.
    del flux.flow
    peak_mem_generation = mx.metal.get_peak_memory() / 1024**3
    mx.metal.reset_peak_memory()

    # Decode them into images
    decoded = []
    for i in tqdm(range(0, args.n_images, args.decoding_batch_size)):
        decoded.append(flux.decode(x_t[i : i + args.decoding_batch_size], latent_size))
        mx.eval(decoded[-1])
    peak_mem_decoding = mx.metal.get_peak_memory() / 1024**3
    peak_mem_overall = max(
        peak_mem_conditioning, peak_mem_generation, peak_mem_decoding
    )

    if args.save_raw:
        *name, suffix = args.output.split(".")
        name = ".".join(name)
        x = mx.concatenate(decoded, axis=0)
        x = (x * 255).astype(mx.uint8)
        for i in range(len(x)):
            im = Image.fromarray(np.array(x[i]))
            im.save(".".join([name, str(i), suffix]))
    else:
        # Arrange them on a grid
        x = mx.concatenate(decoded, axis=0)
        x = mx.pad(x, [(0, 0), (4, 4), (4, 4), (0, 0)])
        B, H, W, C = x.shape
        x = x.reshape(args.n_rows, B // args.n_rows, H, W, C).transpose(0, 2, 1, 3, 4)
        x = x.reshape(args.n_rows * H, B // args.n_rows * W, C)
        x = (x * 255).astype(mx.uint8)

        # Save them to disc
        im = Image.fromarray(np.array(x))
        im.save(args.output)

    # Report the peak memory used during generation
    if args.verbose:
        print(f"Peak memory used for the text:       {peak_mem_conditioning:.3f}GB")
        print(f"Peak memory used for the generation: {peak_mem_generation:.3f}GB")
        print(f"Peak memory used for the decoding:   {peak_mem_decoding:.3f}GB")
        print(f"Peak memory used overall:            {peak_mem_overall:.3f}GB")