megengine.functional.vision 源代码

# -*- coding: utf-8 -*-
# MegEngine is Licensed under the Apache License, Version 2.0 (the "License")
#
# Copyright (c) 2014-2021 Megvii Inc. All rights reserved.
#
# Unless required by applicable law or agreed to in writing,
# software distributed under the License is distributed on an
# "AS IS" BASIS, WITHOUT ARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
from typing import Iterable, Optional, Tuple, Union

import numpy as np

from ..core._imperative_rt.core2 import apply
from ..core.ops import builtin
from ..core.tensor import megbrain_graph, utils
from ..core.tensor.utils import astensor1d
from ..tensor import Tensor
from .elemwise import floor
from .math import argsort
from .tensor import broadcast_to, concat, expand_dims, reshape, transpose


[文档]def cvt_color(inp: Tensor, mode: str = ""): r""" Convert images from one format to another :param inp: input images. :param mode: format mode. :return: convert result. Examples: .. testcode:: import numpy as np import megengine as mge import megengine.functional as F x = mge.tensor(np.array([[[[-0.58675045, 1.7526233, 0.10702174]]]]).astype(np.float32)) y = F.vision.cvt_color(x, mode="RGB2GRAY") print(y.numpy()) Outputs: .. testoutput:: [[[[0.86555195]]]] """ mode = mode.upper() assert mode in builtin.CvtColor.Mode.__dict__, "unspport mode for cvt_color" mode = getattr(builtin.CvtColor.Mode, mode) assert isinstance(mode, builtin.CvtColor.Mode) op = builtin.CvtColor(mode=mode) (out,) = apply(op, inp) return out
[文档]def roi_pooling( inp: Tensor, rois: Tensor, output_shape: Union[int, tuple, list], mode: str = "max", scale: float = 1.0, ) -> Tensor: """ Applies roi pooling on input feature. :param inp: tensor that represents the input feature, `(N, C, H, W)` images. :param rois: `(K, 5)` boxes. First column is the index into N. The other 4 columns are xyxy. :param output_shape: `(height, width)` of output rois feature. :param mode: "max" or "average", use max/average align just like max/average pooling. Default: "max" :param scale: scale the input boxes by this number. Default: 1.0 :return: `(K, C, output_shape[0], output_shape[1])` feature of rois. Examples: .. testcode:: import numpy as np from megengine import tensor import megengine.functional as F np.random.seed(42) inp = tensor(np.random.randn(1, 1, 128, 128)) rois = tensor(np.random.random((4, 5))) y = F.vision.roi_pooling(inp, rois, (2, 2)) print(y.numpy()[0].round(decimals=4)) Outputs: .. testoutput:: [[[-0.1383 -0.1383] [-0.5035 -0.5035]]] """ assert mode.lower() in ["max", "average"], "only max/average mode is supported" if isinstance(output_shape, int): output_shape = (output_shape, output_shape) op = builtin.ROIPooling(mode=mode, scale=scale) result, _ = apply( op, inp, rois, Tensor(output_shape, dtype="int32", device=inp.device) ) return result
[文档]def correlation( data1: Tensor, data2: Tensor, kernel_size: int = 1, max_displacement: int = 1, stride1: int = 1, stride2: int = 1, pad_size: int = 0, is_multiply: bool = True, ) -> Tensor: """ Applies correlation to inputs. :param data1: Input data1 to the correlation. format must be nchw :param data2: Input data2 to the correlation. format must be nchw :param kernel_size: (int (non-negative), optional, default=1) – kernel size for Correlation must be an odd number :param max_displacement: (int (non-negative), optional, default=1) – Max displacement of Correlation :param stride1: (int (non-negative), optional, default=1) – stride1 quantize data1 globally :param stride2: (int (non-negative), optional, default=1) – stride2 quantize data2 within the neighborhood centered around data1 :param pad_size: (int (non-negative), optional, default=0) – pad for Correlation :param is_multiply: (boolean, optional, default=True) – operation type is either multiplication or absolute difference """ op = builtin.Correlation( format="NCHW", kernel_size=kernel_size, max_displacement=max_displacement, stride1=stride1, stride2=stride2, pad_size=pad_size, is_multiply=is_multiply, ) result, *_ = apply(op, data1, data2) return result
[文档]def roi_align( inp: Tensor, rois: Tensor, output_shape: Union[int, tuple, list], mode: str = "average", spatial_scale: float = 1.0, sample_points: Union[int, tuple, list] = 2, aligned: bool = True, ) -> Tensor: """ Applies roi align on input feature. :param inp: tensor that represents the input feature, shape is `(N, C, H, W)`. :param rois: `(N, 5)` boxes. First column is the box index. The other 4 columns are ``xyxy``. :param output_shape: `(height, width)` shape of output rois feature. :param mode: "max" or "average", use max/average align just like max/average pooling. Default: "average" :param spatial_scale: scale the input boxes by this number. Default: 1.0 :param sample_points: number of inputs samples to take for each output sample. 0 to take samples densely. Default: 2 :param aligned: wheather to align the input feature, with `aligned=True`, we first appropriately scale the ROI and then shift it by -0.5. Default: True :return: output tensor. Examples: .. testcode:: import numpy as np from megengine import tensor import megengine.functional as F np.random.seed(42) inp = tensor(np.random.randn(1, 1, 128, 128)) rois = tensor(np.random.random((4, 5))) y = F.vision.roi_align(inp, rois, (2, 2)) print(y.numpy()[0].round(decimals=4)) Outputs: .. testoutput:: [[[0.175 0.175 ] [0.1359 0.1359]]] """ if inp.dtype != np.float32: inp = inp.astype(np.float32) mode = mode.lower() assert mode in ["max", "average"], "only max/average mode is supported" if isinstance(output_shape, int): output_shape = (output_shape, output_shape) pooled_height, pooled_width = output_shape if isinstance(sample_points, int): sample_points = (sample_points, sample_points) sample_height, sample_width = sample_points offset = 0.5 if aligned else 0.0 op = builtin.ROIAlign( mode=mode, format="NCHW", spatial_scale=spatial_scale, offset=offset, pooled_height=pooled_height, pooled_width=pooled_width, sample_height=sample_height, sample_width=sample_width, ) result, *_ = apply(op, inp, rois) return result
[文档]def nms( boxes: Tensor, scores: Tensor, iou_thresh: float, max_output: Optional[int] = None ) -> Tensor: r""" Performs non-maximum suppression (NMS) on the boxes according to their intersection-over-union(IoU). :param boxes: tensor of shape `(N, 4)`; the boxes to perform nms on; each box is expected to be in `(x1, y1, x2, y2)` format. :param iou_thresh: IoU threshold for overlapping. :param scores: tensor of shape `(N,)`, the score of boxes. :param max_output: the maximum number of boxes to keep; it is optional if this operator is not traced otherwise it required to be specified; if it is not specified, all boxes are kept. :return: indices of the elements that have been kept by NMS, sorted by scores. .. note:: max_output should be specified and should have valid positive value under tracing Examples: .. testcode:: import numpy as np from megengine import tensor import megengine.functional as F x = np.zeros((100,4)) np.random.seed(42) x[:,:2] = np.random.rand(100,2)*20 x[:,2:] = np.random.rand(100,2)*20 + 100 scores = tensor(np.random.rand(100)) inp = tensor(x) result = F.vision.nms(inp, scores, iou_thresh=0.7) print(result.numpy()) Outputs: .. testoutput:: [75 69] """ assert ( boxes.ndim == 2 and boxes.shape[1] == 4 ), "the expected shape of boxes is (N, 4)" assert scores.ndim == 1, "the expected shape of scores is (N,)" assert ( boxes.shape[0] == scores.shape[0] ), "number of boxes and scores are not matched" boxes = boxes.detach() scores = scores.detach() sorted_idx = argsort(scores, descending=True) boxes = boxes[sorted_idx] if max_output is None: max_output = boxes.shape[0] op = builtin.NMSKeep(iou_thresh, max_output) inp = (boxes.reshape(1, -1, 4),) indices, count = apply(op, *inp) indices = indices[0][: count[0]] keep_inds = sorted_idx[indices] return keep_inds
[文档]def remap( inp: Tensor, map_xy: Tensor, border_mode: str = "replicate", scalar: float = 0.0, interp_mode: str = "linear", ) -> Tensor: r""" Applies remap transformation to batched 2D images. The input images are transformed to the output images by the tensor map_xy. The output's H and W are same as map_xy's H and W. :param inp: input image :param map_xy: (batch, oh, ow, 2) transformation matrix :param border_mode: pixel extrapolation method. Default: "replicate". Currently also support "constant", "reflect", "reflect_101", "wrap". :param scalar: value used in case of a constant border. Default: 0 :param interp_mode: interpolation methods. Default: "linear". Currently only support "linear" mode. :return: output tensor. Examples: .. testcode:: import numpy as np from megengine import tensor import megengine.functional as F inp_shape = (1, 1, 4, 4) inp = tensor(np.arange(16, dtype=np.float32).reshape(inp_shape)) map_xy_shape = (1, 2, 2, 2) map_xy = tensor(np.array([[[1., 0.],[0., 1.]], [[0., 1.],[0., 1.]]], dtype=np.float32).reshape(map_xy_shape)) out = F.vision.remap(inp, map_xy) print(out.numpy()) Outputs: .. testoutput:: [[[[1. 4.] [4. 4.]]]] """ op = builtin.Remap( imode=interp_mode, border_type=border_mode, format="NCHW", scalar=scalar ) assert isinstance(inp, (Tensor, megbrain_graph.VarNode)), "inp must be Tensor type" (result,) = apply(op, inp, map_xy) return result
[文档]def warp_affine( inp: Tensor, mat: Tensor, out_shape: Union[Tuple[int, int], int, Tensor], border_mode: str = "replicate", border_val: float = 0.0, format: str = "NHWC", interp_mode: str = "linear", ) -> Tensor: """ Batched affine transform on 2D images. :param inp: input image. :param mat: `(batch, 2, 3)` transformation matrix. :param out_shape: output tensor shape. :param border_mode: pixel extrapolation method. Default: "wrap". Currently "constant", "reflect", "reflect_101", "isolated", "wrap", "replicate", "transparent" are supported. :param border_val: value used in case of a constant border. Default: 0 :param format: "NHWC" as default based on historical concerns, "NCHW" is also supported. Default: "NHWC". :param interp_mode: interpolation methods. Could be "linear", "nearest", "cubic", "area". Default: "linear". :return: output tensor. .. note:: Here all available options for params are listed, however it does not mean that you can use all the combinations. On different platforms, different combinations are supported. """ op = builtin.WarpAffine( border_mode=border_mode, border_val=border_val, format=format, imode=interp_mode, ) out_shape = utils.astensor1d(out_shape, inp, dtype="int32", device=inp.device) (result,) = apply(op, inp, mat, out_shape) return result
[文档]def warp_perspective( inp: Tensor, mat: Tensor, out_shape: Union[Tuple[int, int], int, Tensor], mat_idx: Optional[Union[Iterable[int], Tensor]] = None, border_mode: str = "replicate", border_val: float = 0.0, format: str = "NCHW", interp_mode: str = "linear", ) -> Tensor: r""" Applies perspective transformation to batched 2D images. The input images are transformed to the output images by the transformation matrix: .. math:: \text{output}(n, c, h, w) = \text{input} \left( n, c, \frac{M_{00}h + M_{01}w + M_{02}}{M_{20}h + M_{21}w + M_{22}}, \frac{M_{10}h + M_{11}w + M_{12}}{M_{20}h + M_{21}w + M_{22}} \right) Optionally, we can set `mat_idx` to assign different transformations to the same image, otherwise the input images and transformations should be one-to-one correnspondence. :param inp: input image. :param mat: `(batch, 3, 3)` transformation matrix. :param out_shape: `(h, w)` size of the output image. :param mat_idx: `(batch, )` image batch idx assigned to each matrix. Default: None :param border_mode: pixel extrapolation method. Default: "replicate". Currently also support "constant", "reflect", "reflect_101", "wrap". :param border_val: value used in case of a constant border. Default: 0 :param format: "NHWC" is also supported. Default: "NCHW". :param interp_mode: interpolation methods. Default: "linear". Currently only support "linear" mode. :return: output tensor. .. note:: The transformation matrix is the inverse of that used by `cv2.warpPerspective`. Examples: .. testcode:: import numpy as np from megengine import tensor import megengine.functional as F inp_shape = (1, 1, 4, 4) x = tensor(np.arange(16, dtype=np.float32).reshape(inp_shape)) M_shape = (1, 3, 3) # M defines a translation: dst(1, 1, h, w) = rst(1, 1, h+1, w+1) M = tensor(np.array([[1., 0., 1.], [0., 1., 1.], [0., 0., 1.]], dtype=np.float32).reshape(M_shape)) out = F.vision.warp_perspective(x, M, (2, 2)) print(out.numpy()) Outputs: .. testoutput:: [[[[ 5. 6.] [ 9. 10.]]]] """ if inp.dtype == np.float32: mat = mat.astype("float32") if inp.dtype == np.float16: inp = inp.astype("float32") op = builtin.WarpPerspective( imode=interp_mode, bmode=border_mode, format=format, border_val=border_val ) out_shape = astensor1d(out_shape, inp, dtype="int32", device=inp.device) if mat_idx is not None: mat_idx = astensor1d(mat_idx, inp, dtype="int32", device=inp.device) (result,) = apply(op, inp, mat, mat_idx, out_shape) return result (result,) = apply(op, inp, mat, out_shape) return result
[文档]def interpolate( inp: Tensor, size: Optional[Union[int, Tuple[int, int]]] = None, scale_factor: Optional[Union[float, Tuple[float, float]]] = None, mode: str = "bilinear", align_corners: Optional[bool] = None, ) -> Tensor: r""" Down/up samples the input tensor to either the given size or with the given scale_factor. ``size`` can not coexist with ``scale_factor``. :param inp: input tensor. :param size: size of the output tensor. Default: None :param scale_factor: scaling factor of the output tensor. Default: None :param mode: interpolation methods, acceptable values are: "bilinear", "linear", "bicubic" and "nearest". Default: "bilinear" :param align_corners: This only has an effect when `mode` is "bilinear" or "linear". Geometrically, we consider the pixels of the input and output as squares rather than points. If set to ``True``, the input and output tensors are aligned by the center points of their corner pixels, preserving the values at the corner pixels. If set to ``False``, the input and output tensors are aligned by the corner points of their corner pixels, and the interpolation uses edge value padding for out-of-boundary values, making this operation *independent* of input size :return: output tensor. Examples: .. testcode:: import numpy as np from megengine import tensor import megengine.functional as F x = tensor(np.arange(1, 5, dtype=np.float32).reshape(1, 1, 2, 2)) out = F.vision.interpolate(x, [4, 4], align_corners=False) print(out.numpy()) out2 = F.vision.interpolate(x, scale_factor=2.) np.testing.assert_allclose(out.numpy(), out2.numpy()) Outputs: .. testoutput:: [[[[1. 1.25 1.75 2. ] [1.5 1.75 2.25 2.5 ] [2.5 2.75 3.25 3.5 ] [3. 3.25 3.75 4. ]]]] """ mode = mode.lower() if mode not in ["bilinear", "linear", "bicubic", "nearest"]: raise ValueError("unsupported interpolate mode: {}".format(mode)) if mode not in ["bilinear", "linear"]: if align_corners is not None: raise ValueError( "align_corners option can only be set in the bilinear/linear interpolating mode" ) else: if align_corners is None: align_corners = False if ( size is not None and scale_factor is None and not align_corners and mode == "bilinear" and inp.ndim in [4, 5] ): # fastpath for interpolate op = builtin.Resize(imode="linear", format="NCHW") shape = astensor1d(size, inp, dtype="int32", device=inp.device) (result,) = apply(op, inp, shape) return result if mode == "linear": inp = expand_dims(inp, 3) if inp.ndim != 4: raise ValueError("shape of input tensor must correspond to the operartion mode") if size is None: if scale_factor is None: raise ValueError("scale_factor must not be None when size is None") if isinstance(scale_factor, (float, int)): scale_factor = float(scale_factor) if mode == "linear": scale_factor = (scale_factor, float(1)) else: scale_factor = (scale_factor, scale_factor) else: if mode == "linear": raise ValueError( "under linear mode, scale_factor can only be single value" ) assert len(scale_factor) == 2, "shape of scale_factor must be equal to (2, )" assert isinstance(scale_factor[0], float) and isinstance( scale_factor[1], float ), "scale_factor must be float type" dsize = tuple( floor( Tensor( inp.shape[i + 2] * scale_factor[i], dtype="float32", device=inp.device, ) ) for i in range(2) ) dsize = concat([dsize[0], dsize[1]], axis=0) else: if scale_factor is not None: raise ValueError("scale_factor must be None when size is provided") if isinstance(size, int): size = (size, 1) else: if mode == "linear": raise ValueError("under linear mode, size can only be single value") dsize = size oh, ow = dsize[0], dsize[1] ih, iw = inp.shape[2], inp.shape[3] if align_corners: hscale = (ih - 1.0) / (oh - 1.0) wscale = 1.0 * iw / ow if mode != "linear": wscale = (iw - 1.0) / (ow - 1.0) row0 = concat( [wscale, Tensor([0, 0], dtype="float32", device=inp.device)], axis=0 ).reshape(1, 3) row1 = concat( [ Tensor(0, dtype="float32", device=inp.device), hscale, Tensor(0, dtype="float32", device=inp.device), ], axis=0, ).reshape(1, 3) weight = concat( [row0, row1, Tensor([[0, 0, 1]], dtype="float32", device=inp.device)], axis=0, ).reshape(1, 3, 3) weight = broadcast_to(weight, (inp.shape[0], 3, 3)) else: hscale = 1.0 * ih / oh wscale = 1.0 * iw / ow row0 = concat( [wscale, Tensor(0, dtype="float32", device=inp.device), 0.5 * wscale - 0.5], axis=0, ).reshape(1, 3) row1 = concat( [Tensor(0, dtype="float32", device=inp.device), hscale, 0.5 * hscale - 0.5], axis=0, ).reshape(1, 3) weight = concat( [row0, row1, Tensor([[0, 0, 1]], dtype="float32", device=inp.device)], axis=0, ).reshape(1, 3, 3) weight = broadcast_to(weight, (inp.shape[0], 3, 3)) weight = weight.astype("float32") if mode in ["linear", "bilinear"]: ret = warp_perspective(inp, weight, dsize, interp_mode="linear") if mode == "linear": ret = reshape(ret, ret.shape[0:3]) else: # only NHWC format support "cubic" and "nearest" mode inp = transpose(inp, (0, 2, 3, 1)) ret = warp_perspective( inp, weight, dsize, format="NHWC", interp_mode="cubic" if mode == "bicubic" else mode, ) ret = transpose(ret, (0, 3, 1, 2)) return ret
[文档]def nvof(src: Tensor, precision: int = 1) -> Tensor: r""" Implements NVIDIA Optical Flow SDK. :src shape: input tensor with shape (n, t, h, w, c4). :src dtype: uint8. :param precision: 0:NV_OF_PERF_LEVEL_SLOW 1:NV_OF_PERF_LEVEL_MEDIUM 2:NV_OF_PERF_LEVEL_FAST. :output shape: ``(n, t-1, (h+out_grid_size-1)//out_grid_size, (w+out_grid_size-1)//out_grid_size, c2)``. By default, out_grid_size = 4. :output dtype: int16. .. code-block:: python import numpy as np from megengine import tensor import megengine.functional as F x = np.random.random_integers(0, 255, (1,2,224,244,4)).astype("uint8") src = tensor(x) result = F.nn.nvof(src, precision=1) print(result.numpy()) """ assert src.ndim == 5 and src.shape[4] == 4 src = src.detach() op = builtin.NvOf(precision=precision) return apply(op, src)[0]