[Inference] Fix target size mapping for fal-ai's image-to-image (#3399)

* fix target size mapping for image-to-image fal-ai

* docs

* docstring

Author: hanouticelina

src/huggingface_hub/inference/_client.py

@@ -1287,7 +1287,7 @@ def image_to_image(
                 The model to use for inference. Can be a model ID hosted on the Hugging Face Hub or a URL to a deployed
                 Inference Endpoint. This parameter overrides the model defined at the instance level. Defaults to None.
             target_size (`ImageToImageTargetSize`, *optional*):
-                The size in pixel of the output image.
+                The size in pixel of the output image. This parameter is only supported by some providers and for specific models. It will be ignored when unsupported.
 
         Returns:
             `Image`: The translated image.

src/huggingface_hub/inference/_generated/_async_client.py

@@ -1332,7 +1332,7 @@ async def image_to_image(
                 The model to use for inference. Can be a model ID hosted on the Hugging Face Hub or a URL to a deployed
                 Inference Endpoint. This parameter overrides the model defined at the instance level. Defaults to None.
             target_size (`ImageToImageTargetSize`, *optional*):
-                The size in pixel of the output image.
+                The size in pixel of the output image. This parameter is only supported by some providers and for specific models. It will be ignored when unsupported.
 
         Returns:
             `Image`: The translated image.

src/huggingface_hub/inference/_generated/types/image_to_image.py

@@ -33,7 +33,7 @@ class ImageToImageParameters(BaseInferenceType):
     prompt: Optional[str] = None
     """The text prompt to guide the image generation."""
     target_size: Optional[ImageToImageTargetSize] = None
-    """The size in pixel of the output image."""
+    """The size in pixel of the output image. This parameter is only supported by some providers and for specific models. It will be ignored when unsupported."""
 
 
 @dataclass_with_extra

src/huggingface_hub/inference/_providers/fal_ai.py

@@ -191,6 +191,8 @@ def _prepare_payload_as_dict(
         self, inputs: Any, parameters: Dict, provider_mapping_info: InferenceProviderMapping
     ) -> Optional[Dict]:
         image_url = _as_url(inputs, default_mime_type="image/jpeg")
+        if "target_size" in parameters:
+            parameters["image_size"] = parameters.pop("target_size")
         payload: Dict[str, Any] = {
             "image_url": image_url,
             **filter_none(parameters),