Fine-tune ViT Models on Higher Resolution Images

[D0miH]

Hi all,
thank you so much for this awesome library!!

I am using the vision transformer CLIP models and I would like to test some properties with different number of patches.
The problem I have now is that there is only a limited number of models available with different patch sizes. For example, there are only the ViT-B/16 and the ViT-B/32 models, which have the same number of trainable parameters but different patch sizes.

Therefore, I would like to emulate different patch sizes by scaling the input images and fine-tuning the model. I know that the ViTs expect input images of size 224x224. However, in the original CLIP paper (sec. 3.2) they are using higher resolution images for fine-tuning.

So now to my question:

1. Would it be possible to fine-tune the ViT-B/32 model with higher resolution images to emulate an arbitrary smaller batch size?
2. How can I interpolate the positional embeddings? I have found a function for that here within this repository. But as far as I can see, it is never used anywhere.

Thank you so much for your help!

[rwightman]

@D0miH if you pass force_image_size (cmd line --force-image-size) with the new image size to the model factories when you load pretrain weights it will interpolate for you... after that you should create a new config with that image size baked in. The train / eval scripts have that argument too and can be used to evaluate at a different resolution, or to fine-tune at a different resolution.

open_clip/src/open_clip/factory.py

Lines 208 to 253 in 49eac2f

	def create_model(
	model_name: str,
	pretrained: Optional[str] = None,
	precision: str = 'fp32',
	device: Union[str, torch.device] = 'cpu',
	jit: bool = False,
	force_quick_gelu: bool = False,
	force_custom_text: bool = False,
	force_patch_dropout: Optional[float] = None,
	force_image_size: Optional[Union[int, Tuple[int, int]]] = None,
	force_preprocess_cfg: Optional[Dict[str, Any]] = None,
	pretrained_image: bool = False,
	pretrained_hf: bool = True,
	cache_dir: Optional[str] = None,
	output_dict: Optional[bool] = None,
	require_pretrained: bool = False,
	load_weights_only: bool = True,
	**model_kwargs,
	):
	"""Creates and configures a contrastive vision-language model.
	Args:
	model_name: Name of the model architecture to create. Can be a local model name
	or a Hugging Face model ID prefixed with 'hf-hub:'.
	pretrained: Tag/path for pretrained model weights. Can be:
	- A pretrained tag name (e.g., 'openai')
	- A path to local weights
	- None to initialize with random weights
	precision: Model precision/AMP configuration. Options:
	- 'fp32': 32-bit floating point
	- 'fp16'/'bf16': Mixed precision with FP32 for certain layers
	- 'pure_fp16'/'pure_bf16': Pure 16-bit precision
	device: Device to load the model on ('cpu', 'cuda', or torch.device object)
	jit: If True, JIT compile the model
	force_quick_gelu: Force use of QuickGELU activation
	force_custom_text: Force use of custom text encoder
	force_patch_dropout: Override default patch dropout value
	force_image_size: Override default image size for vision encoder
	force_preprocess_cfg: Override default preprocessing configuration
	pretrained_image: Load pretrained weights for timm vision models
	pretrained_hf: Load pretrained weights for HF text models when not loading CLIP weights
	cache_dir: Override default cache directory for downloaded model files
	output_dict: If True and model supports it, return dictionary of features
	require_pretrained: Raise error if pretrained weights cannot be loaded
	load_weights_only: Only deserialize model weights and unpickling torch checkpoints (for safety)
	**model_kwargs: Additional keyword arguments passed to model constructor