TensorFlow 1 version | View source on GitHub |
Extracts crops from the input image tensor and resizes them.
tf.image.crop_and_resize(
image, boxes, box_indices, crop_size, method='bilinear', extrapolation_value=0,
name=None
)
Extracts crops from the input image tensor and resizes them using bilinear
sampling or nearest neighbor sampling (possibly with aspect ratio change) to a
common output size specified by crop_size
. This is more general than the
crop_to_bounding_box
op which extracts a fixed size slice from the input
image and does not allow resizing or aspect ratio change.
Returns a tensor with crops
from the input image
at positions defined at
the bounding box locations in boxes
. The cropped boxes are all resized (with
bilinear or nearest neighbor interpolation) to a fixed
size = [crop_height, crop_width]
. The result is a 4-D tensor
[num_boxes, crop_height, crop_width, depth]
. The resizing is corner aligned.
In particular, if boxes = [[0, 0, 1, 1]]
, the method will give identical
results to using tf.compat.v1.image.resize_bilinear()
or
tf.compat.v1.image.resize_nearest_neighbor()
(depends on the method
argument) with
align_corners=True
.
Args | |
---|---|
image
|
A 4-D tensor of shape [batch, image_height, image_width, depth] .
Both image_height and image_width need to be positive.
|
boxes
|
A 2-D tensor of shape [num_boxes, 4] . The i -th row of the tensor
specifies the coordinates of a box in the box_ind[i] image and is
specified in normalized coordinates [y1, x1, y2, x2] . A normalized
coordinate value of y is mapped to the image coordinate at y *
(image_height - 1) , so as the [0, 1] interval of normalized image
height is mapped to [0, image_height - 1] in image height coordinates.
We do allow y1 > y2 , in which case the sampled crop is an up-down
flipped version of the original image. The width dimension is treated
similarly. Normalized coordinates outside the [0, 1] range are allowed,
in which case we use extrapolation_value to extrapolate the input image
values.
|
box_indices
|
A 1-D tensor of shape [num_boxes] with int32 values in [0,
batch) . The value of box_ind[i] specifies the image that the i -th box
refers to.
|
crop_size
|
A 1-D tensor of 2 elements, size = [crop_height, crop_width] .
All cropped image patches are resized to this size. The aspect ratio of
the image content is not preserved. Both crop_height and crop_width
need to be positive.
|
method
|
An optional string specifying the sampling method for resizing. It
can be either "bilinear" or "nearest" and default to "bilinear" .
Currently two sampling methods are supported: Bilinear and Nearest
Neighbor.
|
extrapolation_value
|
An optional float . Defaults to 0 . Value used for
extrapolation, when applicable.
|
name
|
A name for the operation (optional). |
Returns | |
---|---|
A 4-D tensor of shape [num_boxes, crop_height, crop_width, depth] .
|