Fix "cannot write mode RGBA as JPEG" in Python Pillow

from PIL import Image

def rgba_to_rgb_jpeg(input_path, output_path, bg_color=(255, 255, 255), quality=95):
    """
    Converts any image (RGBA, LA, P, RGB) to a high-quality JPEG with clean background matting.
    """
    with Image.open(input_path) as img:
        # Check if image contains transparency
        if img.mode in ("RGBA", "LA") or (img.mode == "P" and "transparency" in img.info):
            # Ensure full RGBA representation
            rgba_image = img.convert("RGBA")
            
            # Create solid background canvas
            background = Image.new("RGB", rgba_image.size, bg_color)
            
            # Alpha-blend image onto background using 4th channel as mask
            background.paste(rgba_image, mask=rgba_image.split()[3])
            
            # Save optimized JPEG
            background.save(output_path, "JPEG", quality=quality, optimize=True)
        else:
            # Image is already opaque; convert directly
            img.convert("RGB").save(output_path, "JPEG", quality=quality, optimize=True)

# Usage
rgba_to_rgb_jpeg("transparent_logo.png", "logo_clean.jpg")

import os
from pathlib import Path
from concurrent.futures import ThreadPoolExecutor
from PIL import Image

def process_single_file(src_file, dst_dir, bg_color=(255, 255, 255)):
    try:
        out_name = src_file.stem + ".jpg"
        out_path = Path(dst_dir) / out_name
        
        with Image.open(src_file) as img:
            if img.mode in ("RGBA", "LA") or (img.mode == "P" and "transparency" in img.info):
                rgba = img.convert("RGBA")
                bg = Image.new("RGB", rgba.size, bg_color)
                bg.paste(rgba, mask=rgba.split()[3])
                bg.save(out_path, "JPEG", quality=90, optimize=True)
            else:
                img.convert("RGB").save(out_path, "JPEG", quality=90, optimize=True)
        return f"Converted: {src_file.name}"
    except Exception as e:
        return f"Error {src_file.name}: {e}"

def batch_convert_folder(input_folder, output_folder, max_workers=8):
    Path(output_folder).mkdir(parents=True, exist_ok=True)
    image_files = [p for p in Path(input_folder).rglob("*") if p.suffix.lower() in (".png", ".webp")]
    
    print(f"Found {len(image_files)} images. Starting parallel conversion...")
    with ThreadPoolExecutor(max_workers=max_workers) as executor:
        futures = [executor.submit(process_single_file, f, output_folder) for f in image_files]
        for f in futures:
            print(f.result())

# Usage
# batch_convert_folder("./raw_pngs", "./converted_jpegs")

import io
from PIL import Image

def convert_bytes_to_jpeg(input_bytes: bytes, quality: int = 92) -> bytes:
    """
    Accepts raw PNG/WebP bytes, returns clean JPEG bytes in memory.
    """
    with Image.open(io.BytesIO(input_bytes)) as img:
        if img.mode in ("RGBA", "LA") or (img.mode == "P" and "transparency" in img.info):
            rgba = img.convert("RGBA")
            bg = Image.new("RGB", rgba.size, (255, 255, 255))
            bg.paste(rgba, mask=rgba.split()[3])
            out_img = bg
        else:
            out_img = img.convert("RGB")
            
        output_buffer = io.BytesIO()
        out_img.save(output_buffer, format="JPEG", quality=quality)
        return output_buffer.getvalue()

# Example FastAPI Endpoint
"""
@app.post("/upload-avatar/")
async def upload_avatar(file: UploadFile = File(...)):
    contents = await file.read()
    jpeg_bytes = convert_bytes_to_jpeg(contents)
    # Upload jpeg_bytes directly to S3 / GCS
    return {"status": "success", "size": len(jpeg_bytes)}
"""