From 10edfb6f21921a6ba0da1274a774bc5d2bbd3a30 Mon Sep 17 00:00:00 2001
From: LielinJiang <50691816+LielinJiang@users.noreply.github.com>
Date: Thu, 17 Dec 2020 22:10:02 +0800
Subject: [PATCH] Update en docs of to_tensor (#29718)

* update to_tensor en docs
---
 python/paddle/vision/transforms/functional.py    |  4 ++--
 .../paddle/vision/transforms/functional_cv2.py   |  2 +-
 .../paddle/vision/transforms/functional_pil.py   |  2 +-
 python/paddle/vision/transforms/transforms.py    | 16 +++++++++++-----
 4 files changed, 15 insertions(+), 9 deletions(-)

diff --git a/python/paddle/vision/transforms/functional.py b/python/paddle/vision/transforms/functional.py
index 67dff85f57..576415d543 100644
--- a/python/paddle/vision/transforms/functional.py
+++ b/python/paddle/vision/transforms/functional.py
@@ -62,11 +62,11 @@ def to_tensor(pic, data_format='CHW'):
 
     Args:
         pic (PIL.Image|np.ndarray): Image to be converted to tensor.
-        data_format (str, optional): Data format of input img, should be 'HWC' or 
+        data_format (str, optional): Data format of output tensor, should be 'HWC' or 
             'CHW'. Default: 'CHW'.
 
     Returns:
-        Tensor: Converted image. Data format is same as input img.
+        Tensor: Converted image. Data type is same as input img.
 
     Examples:
         .. code-block:: python
diff --git a/python/paddle/vision/transforms/functional_cv2.py b/python/paddle/vision/transforms/functional_cv2.py
index 4cc04c39d0..65884f4ee5 100644
--- a/python/paddle/vision/transforms/functional_cv2.py
+++ b/python/paddle/vision/transforms/functional_cv2.py
@@ -40,7 +40,7 @@ def to_tensor(pic, data_format='CHW'):
 
     Args:
         pic (np.ndarray): Image to be converted to tensor.
-        data_format (str, optional): Data format of img, should be 'HWC' or 
+        data_format (str, optional): Data format of output tensor, should be 'HWC' or 
             'CHW'. Default: 'CHW'.
 
     Returns:
diff --git a/python/paddle/vision/transforms/functional_pil.py b/python/paddle/vision/transforms/functional_pil.py
index 49b02fc049..1f06600b99 100644
--- a/python/paddle/vision/transforms/functional_pil.py
+++ b/python/paddle/vision/transforms/functional_pil.py
@@ -49,7 +49,7 @@ def to_tensor(pic, data_format='CHW'):
 
     Args:
         pic (PIL.Image): Image to be converted to tensor.
-        data_format (str, optional): Data format of img, should be 'HWC' or 
+        data_format (str, optional): Data format of output tensor, should be 'HWC' or 
             'CHW'. Default: 'CHW'.
 
     Returns:
diff --git a/python/paddle/vision/transforms/transforms.py b/python/paddle/vision/transforms/transforms.py
index a24fc888ec..55790d977f 100644
--- a/python/paddle/vision/transforms/transforms.py
+++ b/python/paddle/vision/transforms/transforms.py
@@ -296,15 +296,21 @@ class BaseTransform(object):
 class ToTensor(BaseTransform):
     """Convert a ``PIL.Image`` or ``numpy.ndarray`` to ``paddle.Tensor``.
 
-    Converts a PIL.Image or numpy.ndarray (H x W x C) in the range
-    [0, 255] to a paddle.Tensor of shape (C x H x W) in the range [0.0, 1.0]
-    if the PIL Image belongs to one of the modes (L, LA, P, I, F, RGB, YCbCr, RGBA, CMYK, 1)
-    or if the numpy.ndarray has dtype = np.uint8
+    Converts a PIL.Image or numpy.ndarray (H x W x C) to a paddle.Tensor of shape (C x H x W).
+
+    If input is a grayscale image (H x W), it will be converted to a image of shape (H x W x 1). 
+    And the shape of output tensor will be (1 x H x W).
+
+    If you want to keep the shape of output tensor as (H x W x C), you can set data_format = ``HWC`` .
+
+    Converts a PIL.Image or numpy.ndarray in the range [0, 255] to a paddle.Tensor in the 
+    range [0.0, 1.0] if the PIL Image belongs to one of the modes (L, LA, P, I, F, RGB, YCbCr, 
+    RGBA, CMYK, 1) or if the numpy.ndarray has dtype = np.uint8. 
 
     In the other cases, tensors are returned without scaling.
 
     Args:
-        data_format (str, optional): Data format of input img, should be 'HWC' or 
+        data_format (str, optional): Data format of output tensor, should be 'HWC' or 
             'CHW'. Default: 'CHW'.
         keys (list[str]|tuple[str], optional): Same as ``BaseTransform``. Default: None.
         
-- 
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