sandeep-krishnamurthy closed pull request #13357: Add imresize and
copyMakeBorder to mx.image
URL: https://github.com/apache/incubator-mxnet/pull/13357
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diff --git a/docs/api/python/image/image.md b/docs/api/python/image/image.md
index 0622a30f98a..299c54570b1 100644
--- a/docs/api/python/image/image.md
+++ b/docs/api/python/image/image.md
@@ -18,7 +18,9 @@ images provided in
image.imread
image.imdecode
+ image.imresize
image.scale_down
+ image.copyMakeBorder
image.resize_short
image.fixed_crop
image.random_crop
@@ -166,7 +168,9 @@ and a list of augmenters specific for `Object detection` is
provided
.. automethod:: mxnet.image.imread
.. automethod:: mxnet.image.imdecode
+.. automethod:: mxnet.image.imresize
.. automethod:: mxnet.image.scale_down
+.. automethod:: mxnet.image.copyMakeBorder
.. automethod:: mxnet.image.resize_short
.. automethod:: mxnet.image.fixed_crop
.. automethod:: mxnet.image.random_crop
diff --git a/python/mxnet/image/image.py b/python/mxnet/image/image.py
index 9c2a1cbfba2..b452aecdb04 100644
--- a/python/mxnet/image/image.py
+++ b/python/mxnet/image/image.py
@@ -38,8 +38,6 @@
from ..base import numeric_types
from .. import ndarray as nd
from ..ndarray import _internal
-from ..ndarray._internal import _cvimresize as imresize
-from ..ndarray._internal import _cvcopyMakeBorder as copyMakeBorder
from .. import io
from .. import recordio
@@ -47,7 +45,7 @@
def imread(filename, *args, **kwargs):
"""Read and decode an image to an NDArray.
- Note: `imread` uses OpenCV (not the CV2 Python library).
+ .. note:: `imread` uses OpenCV (not the CV2 Python library).
MXNet must have been built with USE_OPENCV=1 for `imdecode` to work.
Parameters
@@ -85,10 +83,67 @@ def imread(filename, *args, **kwargs):
return _internal._cvimread(filename, *args, **kwargs)
+def imresize(src, w, h, *args, **kwargs):
+ r"""Resize image with OpenCV.
+
+ .. note:: `imresize` uses OpenCV (not the CV2 Python library). MXNet must
have been built
+ with USE_OPENCV=1 for `imresize` to work.
+
+ Parameters
+ ----------
+ src : NDArray
+ source image
+ w : int, required
+ Width of resized image.
+ h : int, required
+ Height of resized image.
+ interp : int, optional, default=1
+ Interpolation method (default=cv2.INTER_LINEAR).
+ Possible values:
+ 0: Nearest Neighbors Interpolation.
+ 1: Bilinear interpolation.
+ 2: Area-based (resampling using pixel area relation). It may be a
+ preferred method for image decimation, as it gives moire-free
+ results. But when the image is zoomed, it is similar to the Nearest
+ Neighbors method. (used by default).
+ 3: Bicubic interpolation over 4x4 pixel neighborhood.
+ 4: Lanczos interpolation over 8x8 pixel neighborhood.
+ 9: Cubic for enlarge, area for shrink, bilinear for others
+ 10: Random select from interpolation method metioned above.
+ Note:
+ When shrinking an image, it will generally look best with AREA-based
+ interpolation, whereas, when enlarging an image, it will generally
look best
+ with Bicubic (slow) or Bilinear (faster but still looks OK).
+ More details can be found in the documentation of OpenCV, please refer
to
+ http://docs.opencv.org/master/da/d54/group__imgproc__transform.html.
+
+ out : NDArray, optional
+ The output NDArray to hold the result.
+
+ Returns
+ -------
+ out : NDArray or list of NDArrays
+ The output of this function.
+
+ Example
+ -------
+ >>> with open("flower.jpeg", 'rb') as fp:
+ ... str_image = fp.read()
+ ...
+ >>> image = mx.img.imdecode(str_image)
+ >>> image
+ <NDArray 2321x3482x3 @cpu(0)>
+ >>> new_image = mx.img.resize(image, 240, 360)
+ >>> new_image
+ <NDArray 240x360x3 @cpu(0)>
+ """
+ return _internal._cvimresize(src, w, h, *args, **kwargs)
+
+
def imdecode(buf, *args, **kwargs):
"""Decode an image to an NDArray.
- Note: `imdecode` uses OpenCV (not the CV2 Python library).
+ .. note:: `imdecode` uses OpenCV (not the CV2 Python library).
MXNet must have been built with USE_OPENCV=1 for `imdecode` to work.
Parameters
@@ -178,6 +233,59 @@ def scale_down(src_size, size):
return int(w), int(h)
+def copyMakeBorder(src, top, bot, left, right, *args, **kwargs):
+ """Pad image border with OpenCV.
+
+ Parameters
+ ----------
+ src : NDArray
+ source image
+ top : int, required
+ Top margin.
+ bot : int, required
+ Bottom margin.
+ left : int, required
+ Left margin.
+ right : int, required
+ Right margin.
+ type : int, optional, default='0'
+ Filling type (default=cv2.BORDER_CONSTANT).
+ 0 - cv2.BORDER_CONSTANT - Adds a constant colored border.
+ 1 - cv2.BORDER_REFLECT - Border will be mirror reflection of the
+ border elements, like this : fedcba|abcdefgh|hgfedcb
+ 2 - cv2.BORDER_REFLECT_101 or cv.BORDER_DEFAULT - Same as above,
+ but with a slight change, like this : gfedcb|abcdefgh|gfedcba
+ 3 - cv2.BORDER_REPLICATE - Last element is replicated throughout,
+ like this: aaaaaa|abcdefgh|hhhhhhh
+ 4 - cv2.BORDER_WRAP - it will look like this : cdefgh|abcdefgh|abcdefg
+ value : double, optional, default=0
+ (Deprecated! Use ``values`` instead.) Fill with single value.
+ values : tuple of <double>, optional, default=[]
+ Fill with value(RGB[A] or gray), up to 4 channels.
+
+ out : NDArray, optional
+ The output NDArray to hold the result.
+
+ Returns
+ -------
+ out : NDArray or list of NDArrays
+ The output of this function.
+
+ Example
+ --------
+ >>> with open("flower.jpeg", 'rb') as fp:
+ ... str_image = fp.read()
+ ...
+ >>> image = mx.img.imdecode(str_image)
+ >>> image
+ <NDArray 2321x3482x3 @cpu(0)>
+ >>> new_image = mx_border = mx.image.copyMakeBorder(mx_img, 1, 2, 3, 4,
type=0)
+ >>> new_image
+ <NDArray 2324x3489x3 @cpu(0)>
+ """
+ return _internal._cvcopyMakeBorder(src, top, bot, left, right, *args,
**kwargs)
+
+
def _get_interp_method(interp, sizes=()):
"""Get the interpolation method for resize functions.
The major purpose of this function is to wrap a random interp method
selection
@@ -236,7 +344,7 @@ def _get_interp_method(interp, sizes=()):
def resize_short(src, size, interp=2):
"""Resizes shorter edge to size.
- Note: `resize_short` uses OpenCV (not the CV2 Python library).
+ .. note:: `resize_short` uses OpenCV (not the CV2 Python library).
MXNet must have been built with OpenCV for `resize_short` to work.
Resizes the original image by setting the shorter edge to size
diff --git a/tests/python/unittest/test_image.py
b/tests/python/unittest/test_image.py
index 4063027cc1e..e0abbd75ef8 100644
--- a/tests/python/unittest/test_image.py
+++ b/tests/python/unittest/test_image.py
@@ -141,7 +141,7 @@ def test_imdecode(self):
try:
import cv2
except ImportError:
- return
+ raise unittest.SkipTest("Unable to import cv2.")
for img in TestImage.IMAGES:
with open(img, 'rb') as fp:
str_image = fp.read()
@@ -175,11 +175,12 @@ def test_scale_down(self):
assert mx.image.scale_down((360, 1000), (480, 500)) == (360, 375)
assert mx.image.scale_down((300, 400), (0, 0)) == (0, 0)
+ @with_seed()
def test_resize_short(self):
try:
import cv2
except ImportError:
- return
+ raise unittest.SkipTest("Unable to import cv2")
for img in TestImage.IMAGES:
cv_img = cv2.imread(img)
mx_img = mx.nd.array(cv_img[:, :, (2, 1, 0)])
@@ -196,6 +197,25 @@ def test_resize_short(self):
mx_resized = mx.image.resize_short(mx_img, new_size,
interp)
assert_almost_equal(mx_resized.asnumpy()[:, :, (2, 1, 0)],
cv_resized, atol=3)
+ @with_seed()
+ def test_imresize(self):
+ try:
+ import cv2
+ except ImportError:
+ raise unittest.SkipTest("Unable to import cv2")
+ for img in TestImage.IMAGES:
+ cv_img = cv2.imread(img)
+ mx_img = mx.nd.array(cv_img[:, :, (2, 1, 0)])
+ new_h = np.random.randint(1, 1000)
+ new_w = np.random.randint(1, 1000)
+ for interp_val in range(0, 2):
+ cv_resized = cv2.resize(cv_img, (new_w, new_h),
interpolation=interp_val)
+ mx_resized = mx.image.imresize(mx_img, new_w, new_h,
interp=interp_val)
+ assert_almost_equal(mx_resized.asnumpy()[:, :, (2, 1, 0)],
cv_resized, atol=3)
+ out_img = mx.nd.zeros((new_h, new_w, 3), dtype=mx_img.dtype)
+ mx.image.imresize(mx_img, new_w, new_h, interp=interp_val,
out=out_img)
+ assert_almost_equal(out_img.asnumpy()[:, :, (2, 1, 0)],
cv_resized, atol=3)
+
def test_color_normalize(self):
for _ in range(10):
mean = np.random.rand(3) * 255
@@ -235,6 +255,31 @@ def test_imageiter(self):
]
_test_imageiter_last_batch(imageiter_list, (2, 3, 224, 224))
+ @with_seed()
+ def test_copyMakeBorder(self):
+ try:
+ import cv2
+ except ImportError:
+ raise unittest.SkipTest("Unable to import cv2")
+ for img in TestImage.IMAGES:
+ cv_img = cv2.imread(img)
+ mx_img = mx.nd.array(cv_img)
+ top = np.random.randint(1, 10)
+ bot = np.random.randint(1, 10)
+ left = np.random.randint(1, 10)
+ right = np.random.randint(1, 10)
+ new_h, new_w, _ = mx_img.shape
+ new_h += top + bot
+ new_w += left + right
+ val = [np.random.randint(1, 255)] * 3
+ for type_val in range(0, 5):
+ cv_border = cv2.copyMakeBorder(cv_img, top, bot, left, right,
borderType=type_val, value=val)
+ mx_border = mx.image.copyMakeBorder(mx_img, top, bot, left,
right, type=type_val, values=val)
+ assert_almost_equal(mx_border.asnumpy(), cv_border)
+ out_img = mx.nd.zeros((new_h , new_w, 3), dtype=mx_img.dtype)
+ mx.image.copyMakeBorder(mx_img, top, bot, left, right,
type=type_val, values=val, out=out_img)
+ assert_almost_equal(out_img.asnumpy(), cv_border)
+
@with_seed()
def test_augmenters(self):
# ColorNormalizeAug
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