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yolov4-keras

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未验证 提交 b765a5c0 编写于 作者: B Bubbliiiing 提交者： GitHub
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Delete yolo4_tiny.py

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from functools import wraps
import numpy as np
import tensorflow as tf
from keras import backend as K
from keras.layers import (Add, Concatenate, Conv2D, MaxPooling2D, UpSampling2D,
ZeroPadding2D)
from keras.layers.advanced_activations import LeakyReLU
from keras.layers.normalization import BatchNormalization
from keras.models import Model
from keras.regularizers import l2
from utils.utils import compose
from nets.CSPdarknet53_tiny import darknet_body
#--------------------------------------------------#
# 单次卷积DarknetConv2D
# 如果步长为2则自己设定padding方式。
# 测试中发现没有l2正则化效果更好，所以去掉了l2正则化
#--------------------------------------------------#
@wraps(Conv2D)
def DarknetConv2D(*args, **kwargs):
# darknet_conv_kwargs = {'kernel_regularizer': l2(5e-4)}
darknet_conv_kwargs = {}
darknet_conv_kwargs['padding'] = 'valid' if kwargs.get('strides')==(2,2) else 'same'
darknet_conv_kwargs.update(kwargs)
return Conv2D(*args, **darknet_conv_kwargs)
#---------------------------------------------------#
# 卷积块
# DarknetConv2D + BatchNormalization + LeakyReLU
#---------------------------------------------------#
def DarknetConv2D_BN_Leaky(*args, **kwargs):
no_bias_kwargs = {'use_bias': False}
no_bias_kwargs.update(kwargs)
return compose(
DarknetConv2D(*args, **no_bias_kwargs),
BatchNormalization(),
LeakyReLU(alpha=0.1))
#---------------------------------------------------#
# 特征层->最后的输出
#---------------------------------------------------#
def yolo_body(inputs, num_anchors, num_classes):
#---------------------------------------------------#
# 生成CSPdarknet53_tiny的主干模型
# feat1的shape为26,26,256
# feat2的shape为13,13,512
#---------------------------------------------------#
feat1, feat2 = darknet_body(inputs)
# 13,13,512 -> 13,13,256
P5 = DarknetConv2D_BN_Leaky(256, (1,1))(feat2)
# 13,13,256 -> 13,13,512 -> 13,13,255
P5_output = DarknetConv2D_BN_Leaky(512, (3,3))(P5)
P5_output = DarknetConv2D(num_anchors*(num_classes+5), (1,1))(P5_output)
# 13,13,256 -> 13,13,128 -> 26,26,128
P5_upsample = compose(DarknetConv2D_BN_Leaky(128, (1,1)), UpSampling2D(2))(P5)
# 26,26,256 + 26,26,128 -> 26,26,384
P4 = Concatenate()([P5_upsample, feat1])
# 26,26,384 -> 26,26,256 -> 26,26,255
P4_output = DarknetConv2D_BN_Leaky(256, (3,3))(P4)
P4_output = DarknetConv2D(num_anchors*(num_classes+5), (1,1))(P4_output)
return Model(inputs, [P5_output, P4_output])
#---------------------------------------------------#
# 将预测值的每个特征层调成真实值
#---------------------------------------------------#
def yolo_head(feats, anchors, num_classes, input_shape, calc_loss=False):
num_anchors = len(anchors)
#---------------------------------------------------#
# [1, 1, 1, num_anchors, 2]
#---------------------------------------------------#
anchors_tensor = K.reshape(K.constant(anchors), [1, 1, 1, num_anchors, 2])
#---------------------------------------------------#
# 获得x，y的网格
# (13, 13, 1, 2)
#---------------------------------------------------#
grid_shape = K.shape(feats)[1:3]
grid_y = K.tile(K.reshape(K.arange(0, stop=grid_shape[0]), [-1, 1, 1, 1]),
[1, grid_shape[1], 1, 1])
grid_x = K.tile(K.reshape(K.arange(0, stop=grid_shape[1]), [1, -1, 1, 1]),
[grid_shape[0], 1, 1, 1])
grid = K.concatenate([grid_x, grid_y])
grid = K.cast(grid, K.dtype(feats))
#---------------------------------------------------#
# 将预测结果调整成(batch_size,13,13,3,85)
# 85可拆分成4 + 1 + 80
# 4代表的是中心宽高的调整参数
# 1代表的是框的置信度
# 80代表的是种类的置信度
#---------------------------------------------------#
feats = K.reshape(feats, [-1, grid_shape[0], grid_shape[1], num_anchors, num_classes + 5])
#---------------------------------------------------#
# 将预测值调成真实值
# box_xy对应框的中心点
# box_wh对应框的宽和高
#---------------------------------------------------#
box_xy = (K.sigmoid(feats[..., :2]) + grid) / K.cast(grid_shape[::-1], K.dtype(feats))
box_wh = K.exp(feats[..., 2:4]) * anchors_tensor / K.cast(input_shape[::-1], K.dtype(feats))
box_confidence = K.sigmoid(feats[..., 4:5])
box_class_probs = K.sigmoid(feats[..., 5:])
#---------------------------------------------------------------------#
# 在计算loss的时候返回grid, feats, box_xy, box_wh
# 在预测的时候返回box_xy, box_wh, box_confidence, box_class_probs
#---------------------------------------------------------------------#
if calc_loss == True:
return grid, feats, box_xy, box_wh
return box_xy, box_wh, box_confidence, box_class_probs
#---------------------------------------------------#
# 对box进行调整，使其符合真实图片的样子
#---------------------------------------------------#
def yolo_correct_boxes(box_xy, box_wh, input_shape, image_shape):
#-----------------------------------------------------------------#
# 把y轴放前面是因为方便预测框和图像的宽高进行相乘
#-----------------------------------------------------------------#
box_yx = box_xy[..., ::-1]
box_hw = box_wh[..., ::-1]
input_shape = K.cast(input_shape, K.dtype(box_yx))
image_shape = K.cast(image_shape, K.dtype(box_yx))
new_shape = K.round(image_shape * K.min(input_shape/image_shape))
#-----------------------------------------------------------------#
# 这里求出来的offset是图像有效区域相对于图像左上角的偏移情况
# new_shape指的是宽高缩放情况
#-----------------------------------------------------------------#
offset = (input_shape-new_shape)/2./input_shape
scale = input_shape/new_shape
box_yx = (box_yx - offset) * scale
box_hw *= scale
box_mins = box_yx - (box_hw / 2.)
box_maxes = box_yx + (box_hw / 2.)
boxes = K.concatenate([
box_mins[..., 0:1], # y_min
box_mins[..., 1:2], # x_min
box_maxes[..., 0:1], # y_max
box_maxes[..., 1:2] # x_max
])
boxes *= K.concatenate([image_shape, image_shape])
return boxes
#---------------------------------------------------#
# 获取每个box和它的得分
#---------------------------------------------------#
def yolo_boxes_and_scores(feats, anchors, num_classes, input_shape, image_shape, letterbox_image):
#-----------------------------------------------------------------#
# 将预测值调成真实值
# box_xy : -1,13,13,3,2;
# box_wh : -1,13,13,3,2;
# box_confidence : -1,13,13,3,1;
# box_class_probs : -1,13,13,3,80;
#-----------------------------------------------------------------#
box_xy, box_wh, box_confidence, box_class_probs = yolo_head(feats, anchors, num_classes, input_shape)
#-----------------------------------------------------------------#
# 在图像传入网络预测前会进行letterbox_image给图像周围添加灰条
# 因此生成的box_xy, box_wh是相对于有灰条的图像的
# 我们需要对齐进行修改，去除灰条的部分。
# 将box_xy、和box_wh调节成y_min,y_max,xmin,xmax
#-----------------------------------------------------------------#
if letterbox_image:
boxes = yolo_correct_boxes(box_xy, box_wh, input_shape, image_shape)
else:
box_yx = box_xy[..., ::-1]
box_hw = box_wh[..., ::-1]
box_mins = box_yx - (box_hw / 2.)
box_maxes = box_yx + (box_hw / 2.)
input_shape = K.cast(input_shape, K.dtype(box_yx))
image_shape = K.cast(image_shape, K.dtype(box_yx))
boxes = K.concatenate([
box_mins[..., 0:1] * image_shape[0], # y_min
box_mins[..., 1:2] * image_shape[1], # x_min
box_maxes[..., 0:1] * image_shape[0], # y_max
box_maxes[..., 1:2] * image_shape[1] # x_max
])
#-----------------------------------------------------------------#
# 获得最终得分和框的位置
#-----------------------------------------------------------------#
boxes = K.reshape(boxes, [-1, 4])
box_scores = box_confidence * box_class_probs
box_scores = K.reshape(box_scores, [-1, num_classes])
return boxes, box_scores
#---------------------------------------------------#
# 图片预测
#---------------------------------------------------#
def yolo_eval(yolo_outputs,
anchors,
num_classes,
image_shape,
max_boxes=20,
score_threshold=.6,
iou_threshold=.5,
letterbox_image=True):
#---------------------------------------------------#
# 获得特征层的数量，有效特征层的数量为3
#---------------------------------------------------#
num_layers = len(yolo_outputs)
#-----------------------------------------------------------#
# 13x13的特征层对应的anchor是[81,82], [135,169], [344,319]
# 26x26的特征层对应的anchor是[23,27], [37,58], [81,82]
#-----------------------------------------------------------#
anchor_mask = [[6,7,8], [3,4,5], [0,1,2]] if num_layers==3 else [[3,4,5], [1,2,3]]
#-----------------------------------------------------------#
# 这里获得的是输入图片的大小，一般是416x416
#-----------------------------------------------------------#
input_shape = K.shape(yolo_outputs[0])[1:3] * 32
boxes = []
box_scores = []
#-----------------------------------------------------------#
# 对每个特征层进行处理
#-----------------------------------------------------------#
for l in range(num_layers):
_boxes, _box_scores = yolo_boxes_and_scores(yolo_outputs[l], anchors[anchor_mask[l]], num_classes, input_shape, image_shape, letterbox_image)
boxes.append(_boxes)
box_scores.append(_box_scores)
#-----------------------------------------------------------#
# 将每个特征层的结果进行堆叠
#-----------------------------------------------------------#
boxes = K.concatenate(boxes, axis=0)
box_scores = K.concatenate(box_scores, axis=0)
#-----------------------------------------------------------#
# 判断得分是否大于score_threshold
#-----------------------------------------------------------#
mask = box_scores >= score_threshold
max_boxes_tensor = K.constant(max_boxes, dtype='int32')
boxes_ = []
scores_ = []
classes_ = []
for c in range(num_classes):
#-----------------------------------------------------------#
# 取出所有box_scores >= score_threshold的框，和成绩
#-----------------------------------------------------------#
class_boxes = tf.boolean_mask(boxes, mask[:, c])
class_box_scores = tf.boolean_mask(box_scores[:, c], mask[:, c])
#-----------------------------------------------------------#
# 非极大抑制
# 保留一定区域内得分最大的框
#-----------------------------------------------------------#
nms_index = tf.image.non_max_suppression(
class_boxes, class_box_scores, max_boxes_tensor, iou_threshold=iou_threshold)
#-----------------------------------------------------------#
# 获取非极大抑制后的结果
# 下列三个分别是
# 框的位置，得分与种类
#-----------------------------------------------------------#
class_boxes = K.gather(class_boxes, nms_index)
class_box_scores = K.gather(class_box_scores, nms_index)
classes = K.ones_like(class_box_scores, 'int32') * c
boxes_.append(class_boxes)
scores_.append(class_box_scores)
classes_.append(classes)
boxes_ = K.concatenate(boxes_, axis=0)
scores_ = K.concatenate(scores_, axis=0)
classes_ = K.concatenate(classes_, axis=0)
return boxes_, scores_, classes_
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