python - 带有彩色蒙版的语义图像分割
问题描述
所以我有一组带有彩色面具的图片,例如蓝色代表椅子,红色代表灯等。
由于我对这一切都不熟悉,因此我尝试使用 unet 模型执行此操作,我已经使用 keras 处理了图像,就像这样。
def data_generator(img_path,mask_path,batch_size):
c=0
n = os.listdir(img_path)
m = os.listdir(mask_path)
random.shuffle(n)
while(True):
img = np.zeros((batch_size,256,256,3)).astype("float")
mask = np.zeros((batch_size,256,256,1)).astype("float")
for i in range(c,c+batch_size):
train_img = cv2.imread(img_path+"/"+n[i])/255.
train_img = cv2.resize(train_img,(256,256))
img[i-c] = train_img
train_mask = cv2.imread(mask_path+"/"+m[i],cv2.IMREAD_GRAYSCALE)/255.
train_mask = cv2.resize(train_mask,(256,256))
train_mask = train_mask.reshape(256,256,1)
mask[i-c]=train_mask
c+=batch_size
if(c+batch_size>=len(os.listdir(img_path))):
c=0
random.shuffle(n)
yield img,mask
现在仔细看,我认为这种方式不适用于我的面具,我尝试将面具处理为 rgb 颜色,但我的模型不会像那样训练。
模型。
def unet(pretrained_weights = None,input_size = (256,256,3)):
inputs = Input(input_size)
conv1 = Conv2D(64, 3, activation = 'relu', padding = 'same', kernel_initializer = 'he_normal')(inputs)
conv1 = Conv2D(64, 3, activation = 'relu', padding = 'same', kernel_initializer = 'he_normal')(conv1)
pool1 = MaxPooling2D(pool_size=(2, 2))(conv1)
conv2 = Conv2D(128, 3, activation = 'relu', padding = 'same', kernel_initializer = 'he_normal')(pool1)
conv2 = Conv2D(128, 3, activation = 'relu', padding = 'same', kernel_initializer = 'he_normal')(conv2)
pool2 = MaxPooling2D(pool_size=(2, 2))(conv2)
conv3 = Conv2D(256, 3, activation = 'relu', padding = 'same', kernel_initializer = 'he_normal')(pool2)
conv3 = Conv2D(256, 3, activation = 'relu', padding = 'same', kernel_initializer = 'he_normal')(conv3)
pool3 = MaxPooling2D(pool_size=(2, 2))(conv3)
conv4 = Conv2D(512, 3, activation = 'relu', padding = 'same', kernel_initializer = 'he_normal')(pool3)
conv4 = Conv2D(512, 3, activation = 'relu', padding = 'same', kernel_initializer = 'he_normal')(conv4)
drop4 = Dropout(0.5)(conv4)
pool4 = MaxPooling2D(pool_size=(2, 2))(drop4)
conv5 = Conv2D(1024, 3, activation = 'relu', padding = 'same', kernel_initializer = 'he_normal')(pool4)
conv5 = Conv2D(1024, 3, activation = 'relu', padding = 'same', kernel_initializer = 'he_normal')(conv5)
drop5 = Dropout(0.5)(conv5)
up6 = Conv2D(512, 2, activation = 'relu', padding = 'same', kernel_initializer = 'he_normal')(UpSampling2D(size = (2,2))(drop5))
merge6 = concatenate([drop4,up6], axis = 3)
conv6 = Conv2D(512, 3, activation = 'relu', padding = 'same', kernel_initializer = 'he_normal')(merge6)
conv6 = Conv2D(512, 3, activation = 'relu', padding = 'same', kernel_initializer = 'he_normal')(conv6)
up7 = Conv2D(256, 2, activation = 'relu', padding = 'same', kernel_initializer = 'he_normal')(UpSampling2D(size = (2,2))(conv6))
merge7 = concatenate([conv3,up7], axis = 3)
conv7 = Conv2D(256, 3, activation = 'relu', padding = 'same', kernel_initializer = 'he_normal')(merge7)
conv7 = Conv2D(256, 3, activation = 'relu', padding = 'same', kernel_initializer = 'he_normal')(conv7)
up8 = Conv2D(128, 2, activation = 'relu', padding = 'same', kernel_initializer = 'he_normal')(UpSampling2D(size = (2,2))(conv7))
merge8 = concatenate([conv2,up8], axis = 3)
conv8 = Conv2D(128, 3, activation = 'relu', padding = 'same', kernel_initializer = 'he_normal')(merge8)
conv8 = Conv2D(128, 3, activation = 'relu', padding = 'same', kernel_initializer = 'he_normal')(conv8)
up9 = Conv2D(64, 2, activation = 'relu', padding = 'same', kernel_initializer = 'he_normal')(UpSampling2D(size = (2,2))(conv8))
merge9 = concatenate([conv1,up9], axis = 3)
conv9 = Conv2D(64, 3, activation = 'relu', padding = 'same', kernel_initializer = 'he_normal')(merge9)
conv9 = Conv2D(64, 3, activation = 'relu', padding = 'same', kernel_initializer = 'he_normal')(conv9)
conv9 = Conv2D(2, 3, activation = 'relu', padding = 'same', kernel_initializer = 'he_normal')(conv9)
conv10 = Conv2D(1, 1, activation = 'sigmoid')(conv9)
model = Model(input = inputs, output = conv10)
model.compile(optimizer = Adam(lr = 1e-4), loss = 'binary_crossentropy', metrics = ['accuracy'])
#model.summary()
if(pretrained_weights):
model.load_weights(pretrained_weights)
return model
所以我的问题是如何训练带有彩色图像蒙版的模型。
编辑,我拥有的数据示例。
以及每个这样的面具的百分比。
{"water": 4.2, "building": 33.5, "road": 0.0}
解决方案
在语义分割问题中,每个像素属于任何目标输出类/标签。因此,您的输出层conv10
应该将类的总数 (n_classes) 作为 no._of_kernels 的值和softmax
如下所示的激活函数:
conv10 = Conv2D(**n_classes**, 1, activation = 'softmax')(conv9)
categorical_crossentropy
在这种情况下,在编译 u-net 模型时也应该将 loss 更改为。
model.compile(optimizer = Adam(lr = 1e-4), loss = 'categorical_crossentropy', metrics = ['accuracy'])
此外,您不应该标准化您的真实标签/蒙版图像,而是可以编码如下:
train_mask = np.zeros((height, width, n_classes))
for c in range(n_classes):
train_mask[:, :, c] = (img == c).astype(int)
[我假设您有两个以上的真实输出类/标签,因为您提到您的面具包含水、道路、建筑物等的不同颜色;如果你只有两个类,那么你的模型配置很好,除了 train_mask 处理。]
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