update doc object detection (#1110)

Co-authored-by: Luca Actis Grosso <[email protected]>
Co-authored-by: Ethan Harris <[email protected]>

docs/source/reference/object_detection.rst

@@ -46,7 +46,7 @@ Here's an outline:
             ...
 
 Once we've downloaded the data using :func:`~flash.core.data.download_data`, we can create the :class:`~flash.image.detection.data.ObjectDetectionData`.
-We select a pre-trained RetinaNet to use for our :class:`~flash.image.detection.model.ObjectDetector` and fine-tune on the COCO 128 data.
+We select a pre-trained EfficientDet to use for our :class:`~flash.image.detection.model.ObjectDetector` and fine-tune on the COCO 128 data.
 We then use the trained :class:`~flash.image.detection.model.ObjectDetector` for inference.
 Finally, we save the model.
 Here's the full example:
@@ -82,26 +82,34 @@ Custom Transformations
 
 Flash automatically applies some default image / mask transformations and augmentations, but you may wish to customize these for your own use case.
 The base :class:`~flash.core.data.io.input_transform.InputTransform` defines 7 hooks for different stages in the data loading pipeline.
-For object-detection tasks, you can leverage the transformations from `Albumentations <https://github.com/albumentations-team/albumentations>`__ with the :class:`~flash.core.integrations.icevision.transforms.IceVisionTransformAdapter`.
+For object-detection tasks, you can leverage the transformations from `Albumentations <https://github.com/albumentations-team/albumentations>`__ with the :class:`~flash.core.integrations.icevision.transforms.IceVisionTransformAdapter`,
+creating a subclass of :class:`~flash.core.data.io.input_transform.InputTransform`
 
 .. code-block:: python
 
+    from dataclasses import dataclass
     import albumentations as alb
     from icevision.tfms import A
 
+    from flash import InputTransform
     from flash.core.integrations.icevision.transforms import IceVisionTransformAdapter
     from flash.image import ObjectDetectionData
 
-    train_transform = {
-        "per_sample_transform": transforms.IceVisionTransformAdapter(
-            [*A.resize_and_pad(128), A.Normalize(), A.Flip(0.4), alb.RandomBrightnessContrast()]
-        )
-    }
+
+    @dataclass
+    class BrightnessContrastTransform(InputTransform):
+        image_size: int = 128
+
+        def per_sample_transform(self):
+            return IceVisionTransformAdapter(
+                [*A.aug_tfms(size=self.image_size), A.Normalize(), alb.RandomBrightnessContrast()]
+            )
+
 
     datamodule = ObjectDetectionData.from_coco(
         train_folder="data/coco128/images/train2017/",
         train_ann_file="data/coco128/annotations/instances_train2017.json",
         val_split=0.1,
-        image_size=128,
-        train_transform=train_transform,
+        train_transform=BrightnessContrastTransform,
+        batch_size=4,
     )