本文主要是介绍DL - 图像分割，希望对大家解决编程问题提供一定的参考价值，需要的开发者们随着小编来一起学习吧！
from transformers import SegformerFeatureExtractor
import PIL.Image#一个把图像转换为数据的工具类
feature_extractor = SegformerFeatureExtractor()#模拟一批数据
pixel_values = [PIL.Image.new('RGB', (200, 100), 'blue'),PIL.Image.new('RGB', (200, 100), 'red')
]value = [PIL.Image.new('L', (200, 100), 150),PIL.Image.new('L', (200, 100), 200)
]#试算
out = feature_extractor(pixel_values, value)
print('keys=', out.keys())
print('type=', type(out['pixel_values']), type(out['labels']))
print('len=', len(out['pixel_values']), len(out['labels']))
print('type0=', type(out['pixel_values'][0]), type(out['labels'][0]))
print('shape0=', out['pixel_values'][0].shape, out['labels'][0].shape)feature_extractor
keys= dict_keys(['pixel_values', 'labels'])
type= <class 'list'> <class 'list'>
len= 2 2
type0= <class 'numpy.ndarray'> <class 'numpy.ndarray'>
shape0= (3, 512, 512) (512, 512)
SegformerFeatureExtractor {"do_normalize": true,"do_resize": true,"feature_extractor_type": "SegformerFeatureExtractor","image_mean": [0.485,0.456,0.406],"image_std": [0.229,0.224,0.225],"reduce_labels": false,"resample": 2,"size": 512
}
from torchvision.transforms import ColorJitter#能对图像进行亮度，对比度，饱和度，色相变换的工具类。其实就是数据增强
jitter = ColorJitter(brightness=0.25, contrast=0.25, saturation=0.25, hue=0.1)print(jitter)jitter(PIL.Image.new('RGB', (200, 100), 'blue'))
ColorJitter(brightness=[0.75, 1.25], contrast=[0.75, 1.25], saturation=[0.75, 1.25], hue=[-0.1, 0.1])
加载数据
from datasets import load_dataset, load_from_disk#一个道路分类数据集
dataset = load_dataset(path='segments/sidewalk-semantic')
# dataset = load_from_disk('datas/segments/sidewalk-semantic')#把图片数据全部转换为数字
def transforms(data):pixel_values = data['pixel_values']label = data['label']#应用数据增强pixel_values = [jitter(i) for i in pixel_values]#编码图片成数字return feature_extractor(pixel_values, label)#切分训练集和测试集
dataset = dataset.shuffle(seed=1)['train'].train_test_split(test_size=0.1)dataset['train'] = dataset['train'].with_transform(transforms)print(dataset['train'][0])dataset
import torchdef collate_fn(data):pixel_values = [i['pixel_values'] for i in data]labels = [i['labels'] for i in data]pixel_values = torch.FloatTensor(pixel_values)labels = torch.LongTensor(labels)return {'pixel_values': pixel_values, 'labels': labels}loader = torch.utils.data.DataLoader(dataset=dataset['train'],batch_size=4,collate_fn=collate_fn,shuffle=True,drop_last=True,
)for i, data in enumerate(loader):breaklen(loader), data['pixel_values'].shape, data['labels'].shape
#因为模型的计算输出是原尺寸除以4，所以需要把结果扩张成原来的大小便于计算正确率什么的
torch.nn.functional.interpolate(torch.randn(4, 35, 128, 128),size=(512, 512),mode='bilinear',align_corners=False).shape
from transformers import SegformerForSemanticSegmentation, SegformerModel#加载模型
#一共35中道路类别，怎么来的不重要
#model = SegformerForSemanticSegmentation.from_pretrained('nvidia/mit-b0',num_labels=35)#定义下游任务模型
class Model(torch.nn.Module):def __init__(self):super().__init__()self.pretrained = SegformerModel.from_pretrained('nvidia/mit-b0')self.linears = torch.nn.ModuleList([torch.nn.Linear(32, 256),torch.nn.Linear(64, 256),torch.nn.Linear(160, 256),torch.nn.Linear(256, 256)])self.classifier = torch.nn.Sequential(torch.nn.Conv2d(in_channels=1024,out_channels=256,kernel_size=1,bias=False),torch.nn.BatchNorm2d(256),torch.nn.ReLU(),torch.nn.Dropout(0.1),torch.nn.Conv2d(256, 35, kernel_size=1),)#加载预训练模型的参数parameters = SegformerForSemanticSegmentation.from_pretrained('nvidia/mit-b0',num_labels=35)for i in range(4):self.linears[i].load_state_dict(parameters.decode_head.linear_c[i].proj.state_dict())self.classifier[0].load_state_dict(parameters.decode_head.linear_fuse.state_dict())self.classifier[1].load_state_dict(parameters.decode_head.batch_norm.state_dict())self.classifier[4].load_state_dict(parameters.decode_head.classifier.state_dict())self.criterion = torch.nn.CrossEntropyLoss(ignore_index=255)def forward(self, pixel_values, labels):#pixel_values -> [4, 3, 512, 512]#labels -> [4, 512, 512]#首先通过预训练模型抽中间特征#[4, 32, 128, 128]#[4, 64, 64, 64]#[4, 160, 32, 32]#[4, 256, 16, 16]features = self.pretrained(pixel_values=pixel_values,output_hidden_states=True)features = features.hidden_states#打平#[4, 32, 16384]#[4, 64, 4096]#[4, 160, 1024]#[4, 256, 256]features = [i.flatten(2) for i in features]#转置，把通道放到最后一个维度#[4, 16384, 32]#[4, 4096, 64]#[4, 1024, 160]#[4, 256, 256]features = [i.transpose(1, 2) for i in features]#线性计算#[4, 16384, 256]#[4, 4096, 256]#[4, 1024, 256]#[4, 256, 256]features = [l(f) for f, l in zip(features, self.linears)]#转置回来，把通道放中间#[4, 256, 16384]#[4, 256, 4096]#[4, 256, 1024]#[4, 256, 256]features = [i.permute(0, 2, 1) for i in features]#变形成二维的图片#[4, 256, 128, 128]#[4, 256, 64, 64]#[4, 256, 32, 32]#[4, 256, 16, 16]features = [f.reshape(pixel_values.shape[0], -1, s, s)for f, s in zip(features, [128, 64, 32, 16])]#拓展到统一的尺寸#[4, 256, 128, 128]#[4, 256, 128, 128]#[4, 256, 128, 128]#[4, 256, 128, 128]features = [torch.nn.functional.interpolate(i,size=(128, 128),mode='bilinear',align_corners=False)for i in features]#逆序，维度不变features = features[::-1]#在通道维度合并成一个张量#[4, 1024, 128, 128]features = torch.cat(features, dim=1)#跑分类网络，其中包括了1024->256->35两步，使用cnn网络实现#[4, 35, 128, 128]features = self.classifier(features)#为了计算loss，要把计算结果放大到和labels一致#[4, 35, 128, 128] -> [4, 35, 512, 512]#计算交叉熵lossloss = self.criterion(torch.nn.functional.interpolate(features,size=(512, 512),mode='bilinear',align_corners=False), labels)return {'loss': loss, 'logits': features}model = Model()#统计参数量
print(sum(i.numel() for i in model.parameters()) / 10000)out = model(**data)out['loss'], out['logits'].shape
from datasets import load_metric#加载评价指标
metric = load_metric('mean_iou')#试算
metric.compute(predictions=torch.ones(4, 10, 10),references=torch.ones(4, 10, 10),#一共35中道路类别，怎么来的不重要num_labels=35,#忽略背景类0ignore_index=0,reduce_labels=False)
from matplotlib import pyplot as pltdef show(image, out, label):plt.figure(figsize=(15, 5))image = image.clone()image = image.permute(1, 2, 0)image = image - image.min().item()image = image / image.max().item()image = image * 255image = PIL.Image.fromarray(image.numpy().astype('uint8'), mode='RGB')image = image.resize((512, 512))plt.subplot(1, 3, 1)plt.imshow(image)plt.axis('off')out = PIL.Image.fromarray(out.numpy().astype('uint8'))plt.subplot(1, 3, 2)plt.imshow(out)plt.axis('off')label = PIL.Image.fromarray(label.numpy().astype('uint8'))plt.subplot(1, 3, 3)plt.imshow(label)plt.axis('off')plt.show()show(data['pixel_values'][0], torch.ones(512, 512), data['labels'][0])
测试
def test():model.eval()dataset['test'] = dataset['test'].shuffle()loader_test = torch.utils.data.DataLoader(dataset=dataset['test'].with_transform(transforms),batch_size=8,collate_fn=collate_fn,shuffle=False,drop_last=True,)labels = []outs = []correct = 0#初始化为1，防止除0total = 1for i, data in enumerate(loader_test):with torch.no_grad():out = model(**data)#运算结果扩张4倍out = torch.nn.functional.interpolate(out['logits'],size=(512, 512),mode='bilinear',align_corners=False)out = out.argmax(dim=1)outs.append(out)label = data['labels']labels.append(label)#统计正确率时排除label中的0select = label != 0correct += (label[select] == out[select]).sum().item()total += len(label[select])if i % 1 == 0:show(data['pixel_values'][0], out[0], label[0])if i == 4:break#计算评价指标metric_out = metric.compute(predictions=torch.cat(outs, dim=0),references=torch.cat(labels, dim=0),num_labels=35,ignore_index=0)#删除这两个结果，不想看metric_out.pop('per_category_iou')metric_out.pop('per_category_accuracy')print(metric_out)print(correct / total)test()
训练
from transformers import AdamW
from transformers.optimization import get_schedulerdef train():optimizer = AdamW(model.parameters(), lr=5e-5)scheduler = get_scheduler(name='linear',num_warmup_steps=0,num_training_steps=len(loader) * 3,optimizer=optimizer)model.train()for i, data in enumerate(loader):out = model(**data)loss = out['loss']loss.backward()torch.nn.utils.clip_grad_norm_(model.parameters(), 1.0)optimizer.step()scheduler.step()optimizer.zero_grad()model.zero_grad()if i % 10 == 0:#运算结果扩张4倍out = torch.nn.functional.interpolate(out['logits'],size=(512, 512),mode='bilinear',align_corners=False).argmax(dim=1)label = data['labels']#计算评价指标metric_out = metric.compute(predictions=out,references=label,num_labels=35,ignore_index=0)#删除这两个结果，不想看metric_out.pop('per_category_iou')metric_out.pop('per_category_accuracy')#统计正确率时排除label中的0select = label != 0label = label[select]out = out[select]#防止除0accuracy = (label == out).sum().item() / (len(label) + 1)lr = optimizer.state_dict()['param_groups'][0]['lr']print(i, loss.item(), lr, metric_out, accuracy)torch.save(model, 'models/9.抠图.model')train()
model = torch.load('models/9.抠图.model')
test()
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