downscale_imgs.py

import os
import cv2
import sys

# Downscale factor
scale_factor = 2

# Function to process and save images
def downscale_and_save_images(input_dir, output_dir, factor):
    for root, dirs, files in os.walk(input_dir):
        for file in files:
            if file.lower().endswith(('.png', '.jpg', '.jpeg')):
                # Construct full input path
                img_path = os.path.join(root, file)
                print("cur img:",img_path)
                # Read image
                image = cv2.imread(img_path,cv2.IMREAD_UNCHANGED)
                if image is None:
                    print(f"Failed to load {file}")
                    continue
                
                # Calculate new dimensions
                new_width = int(image.shape[1] / factor)
                new_height = int(image.shape[0] / factor)
                
                # Downscale image using bicubic interpolation
                downscaled_image = cv2.resize(image, (new_width, new_height), interpolation=cv2.INTER_CUBIC)
                
                # Construct output path and save image
                base_name, ext = os.path.splitext(file)
                output_path = os.path.join(output_dir, f"{base_name}x2{ext}")
                cv2.imwrite(output_path, downscaled_image)
                print(f"Saved downscaled image: {output_path}")

def printUsageAndExit():
    print("Usage: python3 " + sys.argv[0] + " input_HR_folder output_LR_X2 folder")
    sys.exit(-1)

# Run the function
if len(sys.argv) < 2:
    printUsageAndExit()

input_folder=sys.argv[1]
output_folder=sys.argv[2]

if os.path.isdir(input_folder) is False:
    print("Cannot find existing input folder: " + input_folder)
    sys.exit(-1)

os.makedirs(output_folder, exist_ok=True)
if os.path.isdir(output_folder) is False:
    print("Unable to create output folder: " + output_folder)
    sys.exit(-1)


print("Input Folder: " + input_folder)
print("Output Folder: " + output_folder)

downscale_and_save_images(input_folder, output_folder, scale_factor)