Pytorch 使用 nii資料做輸入資料的操作
使用pix2pix-gan做醫學影象合成的時候,如果把nii資料轉成png格式會損失很多資訊,以為png格式影象的灰度值有256階,因此直接使用nii的醫學影象做輸入會更好一點。
但是Pythorch中的Dataloader是不能直接讀取nii影象的,因此加一個CreateNiiDataset的類。
先來了解一下pytorch中讀取資料的主要途徑——Dataset類。在自己構建資料層時都要基於這個類,類似於C++中的虛基類。
自己構建的資料層包含三個部分
class Dataset(object): """An abstract class representing a Dataset. All other datasets should subclass it. All subclasses should override ``__len__``,that provides the size of the dataset,and ``__getitem__``,supporting integer indexing in range from 0 to len(self) exclusive. """ def __getitem__(self,index): raise NotImplementedError def __len__(self): raise NotImplementedError def __add__(self,other): return ConcatDataset([self,other])
根據自己的需要編寫CreateNiiDataset子類:
因為我是基於https://github.com/junyanz/pytorch-CycleGAN-and-pix2pix
做pix2pix-gan的實驗,資料包含兩個部分mr 和 ct,不需要標籤,因此上面的 def getitem(self,index):中不需要index這個引數了,類似地,根據需要,加入自己的引數,去掉不需要的引數。
class CreateNiiDataset(Dataset): def __init__(self,opt,transform = None,target_transform = None): self.path1 = opt.dataroot # parameter passing self.A = 'MR' self.B = 'CT' lines = os.listdir(os.path.join(self.path1,self.A)) lines.sort() imgs = [] for line in lines: imgs.append(line) self.imgs = imgs self.transform = transform self.target_transform = target_transform def crop(self,image,crop_size): shp = image.shape scl = [int((shp[0] - crop_size[0]) / 2),int((shp[1] - crop_size[1]) / 2)] image_crop = image[scl[0]:scl[0] + crop_size[0],scl[1]:scl[1] + crop_size[1]] return image_crop def __getitem__(self,item): file = self.imgs[item] img1 = sitk.ReadImage(os.path.join(self.path1,self.A,file)) img2 = sitk.ReadImage(os.path.join(self.path1,self.B,file)) data1 = sitk.GetArrayFromImage(img1) data2 = sitk.GetArrayFromImage(img2) if data1.shape[0] != 256: data1 = self.crop(data1,[256,256]) data2 = self.crop(data2,256]) if self.transform is not None: data1 = self.transform(data1) data2 = self.transform(data2) if np.min(data1)<0: data1 = (data1 - np.min(data1))/(np.max(data1)-np.min(data1)) if np.min(data2)<0: #data2 = data2 - np.min(data2) data2 = (data2 - np.min(data2))/(np.max(data2)-np.min(data2)) data = {} data1 = data1[np.newaxis,np.newaxis,:,:] data1_tensor = torch.from_numpy(np.concatenate([data1,data1,data1],1)) data1_tensor = data1_tensor.type(torch.FloatTensor) data['A'] = data1_tensor # should be a tensor in Float Tensor Type data2 = data2[np.newaxis,:] data2_tensor = torch.from_numpy(np.concatenate([data2,data2,data2],1)) data2_tensor = data2_tensor.type(torch.FloatTensor) data['B'] = data2_tensor # should be a tensor in Float Tensor Type data['A_paths'] = [os.path.join(self.path1,file)] # should be a list,with path inside data['B_paths'] = [os.path.join(self.path1,file)] return data def load_data(self): return self def __len__(self): return len(self.imgs)
注意:最後輸出的data是一個字典,裡面有四個keys=[‘A',‘B',‘A_paths',‘B_paths'],一定要注意資料要轉成FloatTensor。
其次是data[‘A_paths'] 接收的值是一個list,一定要加[ ] 擴起來,要不然測試存圖的時候會有問題,找這個問題找了好久才發現。
然後直接在train.py的主函式裡面把資料載入那行改掉就好了
data_loader = CreateNiiDataset(opt)
dataset = data_loader.load_data()
Over!
補充知識:nii格式影象存為npy格式
我就廢話不多說了,大家還是直接看程式碼吧!
import nibabel as nib import os import numpy as np img_path = '/home/lei/train/img/' seg_path = '/home/lei/train/seg/' saveimg_path = '/home/lei/train/npy_img/' saveseg_path = '/home/lei/train/npy_seg/' img_names = os.listdir(img_path) seg_names = os.listdir(seg_path) for img_name in img_names: print(img_name) img = nib.load(img_path + img_name).get_data() #載入 img = np.array(img) np.save(saveimg_path + str(img_name).split('.')[0] + '.npy',img) #儲存 for seg_name in seg_names: print(seg_name) seg = nib.load(seg_path + seg_name).get_data() seg = np.array(seg) np.save(saveseg_path + str(seg_name).split('.')[0] + '.npy
以上這篇Pytorch 使用 nii資料做輸入資料的操作就是小編分享給大家的全部內容了,希望能給大家一個參考,也希望大家多多支援我們。