Creating Annotation File with Class Labels

This example shows how to create VL annotations file using subfolder structure, each subfolder is the class label.
The root folder of the dataset contains 3 subfolders which are the classes: Ulcer, Normal and AVM.

import os  
import csv

def create_annotation_csv(root_dir, output_csv):  
    rows = []

    # Iterate over all items in the root directory.
    for subdir in os.listdir(root_dir):
        subdir_path = os.path.join(root_dir, subdir)
        if os.path.isdir(subdir_path):
            label = subdir  # The subfolder name is the label.
            # Iterate over each file in the subdirectory.
            for filename in os.listdir(subdir_path):
                file_path = os.path.join(subdir_path, filename)
                if os.path.isfile(file_path):
                    # Build the relative file path (e.g., "b/image1.jpg").
                    relative_path = os.path.join(subdir, filename)
                    rows.append([relative_path, label])

    # Write the CSV file with header "filename,label".
    with open(output_csv, mode='w', newline='') as csv_file:
        writer = csv.writer(csv_file)
        writer.writerow(['filename', 'label'])
        writer.writerows(rows)
    print(f"CSV file '{output_csv}' created successfully.")

if __name__ == "__main__":  
    root_directory = "."  # Folder containing your subfolders.  
    output_csv_file = "image_annotations.csv"  
    create_annotation_csv(root_directory, output_csv_file)

Example output:

filename,label
Ulcer/Ulcer_2024-08-07-08-28-10_81061.bmp,Ulcer
Ulcer/Ulcer_2024-08-07-08-29-37_82025.bmp,Ulcer
Ulcer/Ulcer_2024-08-07-08-29-07_43887.bmp,Ulcer
Ulcer/Ulcer_2024-08-07-08-28-10_43888.bmp,Ulcer
Ulcer/Ulcer_2024-08-07-08-30-31_30154.bmp,Ulcer
Ulcer/Ulcer_2024-08-07-08-27-27_96319.bmp,Ulcer