PandaTouch image in Python

panda.py

from PIL import Image
import struct

def process_image(input_file, output_file, max_size=(250, 250)):
    # Open the image using PIL
    with Image.open(input_file) as img:
        # Scale the image down to fit within max_size while maintaining aspect ratio
        img.thumbnail(max_size)

        # Ensure the image is in RGBA mode
        img = img.convert('RGBA')
        width, height = img.size

        # Prepare the binary content
        binary_content = bytearray()

        header = bytes.fromhex('DFAD000001F26E65775F70616E64612E706E67000000')
        binary_content.extend(header)

        # Pack the size as a 4-byte unsigned integer in little endian
        size_bytes = struct.pack('<I', width * height * 3 + 4)
        binary_content.extend(size_bytes)

        dimensions = ((height * 4) << 19) + ((width * 4) << 8) + 5
        dimensions_bytes = struct.pack('<I', dimensions)
        binary_content.extend(dimensions_bytes)

        # Process each pixel row by row
        for y in range(height):
            for x in range(width):
                r, g, b, a = img.getpixel((x, y))

                pixel = (a << 16) + ((r >> 3) << 11) + ((g >> 2) << 5) + (b >>3)
                pixel_bytes = struct.pack('<I', pixel)[:3]

                binary_content.extend(pixel_bytes)

        # Write the binary content to the output file
        with open(output_file, 'wb') as f:
            f.write(binary_content)

credit: bigtreetech/PandaTouch#108 (comment)