[textual inversion] Allow validation images (#2077)

* [textual inversion] Allow validation images.

* Change key to `validation`

* Specify format instead of transposing.

As discussed with @sayakpaul.

* Style
Co-authored-by: isamu-isozaki <isamu.website@gmail.com>

examples/textual_inversion/textual_inversion.py

@@ -34,9 +34,16 @@ import transformers
 from accelerate import Accelerator
 from accelerate.logging import get_logger
 from accelerate.utils import set_seed
-from diffusers import AutoencoderKL, DDPMScheduler, StableDiffusionPipeline, UNet2DConditionModel
+from diffusers import (
+    AutoencoderKL,
+    DDPMScheduler,
+    DiffusionPipeline,
+    DPMSolverMultistepScheduler,
+    StableDiffusionPipeline,
+    UNet2DConditionModel,
+)
 from diffusers.optimization import get_scheduler
-from diffusers.utils import check_min_version
+from diffusers.utils import check_min_version, is_wandb_available
 from diffusers.utils.import_utils import is_xformers_available
 from huggingface_hub import HfFolder, Repository, create_repo, whoami
 
@@ -250,6 +257,28 @@ def parse_args():
             ' (default), `"wandb"` and `"comet_ml"`. Use `"all"` to report to all integrations.'
         ),
     )
+    parser.add_argument(
+        "--validation_prompt",
+        type=str,
+        default=None,
+        help="A prompt that is used during validation to verify that the model is learning.",
+    )
+    parser.add_argument(
+        "--num_validation_images",
+        type=int,
+        default=4,
+        help="Number of images that should be generated during validation with `validation_prompt`.",
+    )
+    parser.add_argument(
+        "--validation_epochs",
+        type=int,
+        default=50,
+        help=(
+            "Run validation every X epochs. Validation consists of running the prompt"
+            " `args.validation_prompt` multiple times: `args.num_validation_images`"
+            " and logging the images."
+        ),
+    )
     parser.add_argument("--local_rank", type=int, default=-1, help="For distributed training: local_rank")
     parser.add_argument(
         "--checkpointing_steps",
@@ -444,6 +473,11 @@ def main():
         logging_dir=logging_dir,
     )
 
+    if args.report_to == "wandb":
+        if not is_wandb_available():
+            raise ImportError("Make sure to install wandb if you want to use it for logging during training.")
+        import wandb
+
     # Make one log on every process with the configuration for debugging.
     logging.basicConfig(
         format="%(asctime)s - %(levelname)s - %(name)s - %(message)s",
@@ -740,6 +774,45 @@ def main():
             if global_step >= args.max_train_steps:
                 break
 
+        if args.validation_prompt is not None and epoch % args.validation_epochs == 0:
+            logger.info(
+                f"Running validation... \n Generating {args.num_validation_images} images with prompt:"
+                f" {args.validation_prompt}."
+            )
+            # create pipeline (note: unet and vae are loaded again in float32)
+            pipeline = DiffusionPipeline.from_pretrained(
+                args.pretrained_model_name_or_path,
+                text_encoder=accelerator.unwrap_model(text_encoder),
+                revision=args.revision,
+            )
+            pipeline.scheduler = DPMSolverMultistepScheduler.from_config(pipeline.scheduler.config)
+            pipeline = pipeline.to(accelerator.device)
+            pipeline.set_progress_bar_config(disable=True)
+
+            # run inference
+            generator = (
+                None if args.seed is None else torch.Generator(device=accelerator.device).manual_seed(args.seed)
+            )
+            prompt = args.num_validation_images * [args.validation_prompt]
+            images = pipeline(prompt, num_inference_steps=25, generator=generator).images
+
+            for tracker in accelerator.trackers:
+                if tracker.name == "tensorboard":
+                    np_images = np.stack([np.asarray(img) for img in images])
+                    tracker.writer.add_images("validation", np_images, epoch, dataformats="NHWC")
+                if tracker.name == "wandb":
+                    tracker.log(
+                        {
+                            "validation": [
+                                wandb.Image(image, caption=f"{i}: {args.validation_prompt}")
+                                for i, image in enumerate(images)
+                            ]
+                        }
+                    )
+
+            del pipeline
+            torch.cuda.empty_cache()
+
     # Create the pipeline using using the trained modules and save it.
     accelerator.wait_for_everyone()
     if accelerator.is_main_process: