Function _encode_image

src/utils/image_processor.py:184–218

Encode a PIL Image to bytes in the given media type. Supports only the four Anthropic API image types. Raises ``ImageProcessingError`` for any other media_type so the caller can't silently mislabel bytes (e.g. asking for image/tiff and getting PNG bytes back tagged as image/tiff — w

(img: Any, media_type: str, quality: int | None = None)

def _encode_image(img: Any, media_type: str, quality: int | None = None) -> bytes:
    """Encode a PIL Image to bytes in the given media type.

    Supports only the four Anthropic API image types. Raises
    ``ImageProcessingError`` for any other media_type so the caller can't
    silently mislabel bytes (e.g. asking for image/tiff and getting PNG
    bytes back tagged as image/tiff — which the API would reject).
    """
    if media_type not in _SUPPORTED_ENCODE_TYPES:
        raise ImageProcessingError(
            f"Unsupported image encoding type: {media_type}. "
            f"Supported: {sorted(_SUPPORTED_ENCODE_TYPES)}"
        )
    buf = io.BytesIO()
    if media_type == "image/png":
        # Plain optimized PNG. Palette quantization happens in
        # ``compress_image_to_byte_budget`` step 2 (where it's gated on
        # the source being PNG); keeping it out of the default encode
        # path preserves alpha for opaque-vs-transparent inputs alike.
        save_kwargs: dict[str, Any] = {"format": "PNG", "optimize": True, "compress_level": 9}
        img.save(buf, **save_kwargs)
    elif media_type == "image/jpeg":
        # JPEG requires RGB; convert if image has alpha/palette.
        if img.mode not in ("RGB", "L"):
            img = img.convert("RGB")
        save_kwargs = {"format": "JPEG", "quality": quality or 80, "optimize": True}
        img.save(buf, **save_kwargs)
    elif media_type == "image/webp":
        save_kwargs = {"format": "WEBP", "quality": quality or 80}
        img.save(buf, **save_kwargs)
    elif media_type == "image/gif":
        # GIF re-encode preserves palette but loses transparency in some
        # frames; acceptable per TS behavior.
        img.save(buf, format="GIF")
    return buf.getvalue()


def _resize_to_envelope(img: Any, max_w: int, max_h: int) -> tuple[Any, int, int]: