我有一个faces
列表,其中列表的每个元素都是一个具有形状(1,224,224,3)的numpy数组,即人脸图像。我有一个模型,它的输入形状是(None, 224, 224, 3)
,输出形状是(None, 2)
现在我想对faces
列表中的所有图像进行预测。当然,我可以遍历列表并逐个获得预测,但我希望将所有图像作为一个批处理,只需一次调用model.predict()
即可更快地获得结果
如果我像现在一样直接传递faces列表(最后完成代码),我只会得到第一张图像的预测
print(f"{len(faces)} faces found")
print(faces[0].shape)
maskPreds = model.predict(faces)
print(maskPreds)
输出:
3 faces found
(1, 224, 224, 3)
[[0.9421933 0.05780665]]
但是maskPreds
对于3个图像应该是这样的:
[[0.9421933 0.05780665],
[0.01584494 0.98415506],
[0.09914105 0.9008589 ]]
完整代码:
from tensorflow.keras.models import load_model
from cvlib import detect_face
import cv2
import numpy as np
def detectAllFaces(frame):
dets = detect_face(frame)
boxes = dets[0]
confidences = dets[1]
faces = []
for box, confidence in zip(boxes, confidences):
startX, startY, endX, endY = box
cv2.rectangle(frame, (startX, startY), (endX, endY), (0, 255, 0), 1)
face = frame[startY:endY, startX:endX]
face = cv2.resize(face, (224, 224))
face = np.expand_dims(face, axis=0) # convert (224,224,3) to (1,224,224,3)
faces.append(face)
return faces, frame
model = load_model("mask_detector.model")
vs = cv2.VideoCapture(0)
model.summary()
while True:
ret, frame = vs.read()
if not ret:
break
faces, frame = detectAllFaces(frame)
if len(faces):
print(f"{len(faces)} faces found")
maskPreds = model.predict(faces) # <==========
print(maskPreds)
cv2.imshow("Window", frame)
if cv2.waitKey(1) == ord('q'):
break
cv2.destroyWindow("Window")
vs.release()
注意:如果我不将每个图像从(224224,224,3)转换为(1224,224,3),tensorflow会抛出错误,表示输入维度不匹配
ValueError: Error when checking input: expected input_1 to have 4 dimensions, but got array with shape (224, 224, 3)
如何实现批量预测?
在这种情况下
model.predict()
函数的输入需要作为形状(N,224,224,3)的numpy数组给出,其中N是输入图像的数量为了实现这一点,我们可以将N大小为(1224224,3)的单个numpy数组堆叠成一个大小为(N,224224224,3)的数组,然后将其传递给
model.predict()
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