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from models.med import BertConfig, BertModel | |
from transformers import BertTokenizer | |
import torch | |
from torch import nn | |
import torch.nn.functional as F | |
from models.blip import create_vit, init_tokenizer, load_checkpoint | |
class BLIP_ITM(nn.Module): | |
def __init__(self, | |
med_config = 'configs/med_config.json', | |
image_size = 384, | |
vit = 'base', | |
vit_grad_ckpt = False, | |
vit_ckpt_layer = 0, | |
embed_dim = 256, | |
): | |
""" | |
Args: | |
med_config (str): path for the mixture of encoder-decoder model's configuration file | |
image_size (int): input image size | |
vit (str): model size of vision transformer | |
""" | |
super().__init__() | |
self.visual_encoder, vision_width = create_vit(vit,image_size, vit_grad_ckpt, vit_ckpt_layer) | |
self.tokenizer = init_tokenizer() | |
med_config = BertConfig.from_json_file(med_config) | |
med_config.encoder_width = vision_width | |
self.text_encoder = BertModel(config=med_config, add_pooling_layer=False) | |
text_width = self.text_encoder.config.hidden_size | |
self.vision_proj = nn.Linear(vision_width, embed_dim) | |
self.text_proj = nn.Linear(text_width, embed_dim) | |
self.itm_head = nn.Linear(text_width, 2) | |
def forward(self, image, caption, match_head='itm'): | |
image_embeds = self.visual_encoder(image) | |
image_atts = torch.ones(image_embeds.size()[:-1],dtype=torch.long).to(image.device) | |
text = self.tokenizer(caption, padding='max_length', truncation=True, max_length=35, | |
return_tensors="pt").to(image.device) | |
if match_head=='itm': | |
output = self.text_encoder(text.input_ids, | |
attention_mask = text.attention_mask, | |
encoder_hidden_states = image_embeds, | |
encoder_attention_mask = image_atts, | |
return_dict = True, | |
) | |
itm_output = self.itm_head(output.last_hidden_state[:,0,:]) | |
return itm_output | |
elif match_head=='itc': | |
text_output = self.text_encoder(text.input_ids, attention_mask = text.attention_mask, | |
return_dict = True, mode = 'text') | |
image_feat = F.normalize(self.vision_proj(image_embeds[:,0,:]),dim=-1) | |
text_feat = F.normalize(self.text_proj(text_output.last_hidden_state[:,0,:]),dim=-1) | |
sim = image_feat @ text_feat.t() | |
return sim | |
def blip_itm(pretrained='',**kwargs): | |
model = BLIP_ITM(**kwargs) | |
if pretrained: | |
model,msg = load_checkpoint(model,pretrained) | |
assert(len(msg.missing_keys)==0) | |
return model | |