+/** Create an image for this frame.
+ * @param note Handler for any notes that are made during the process.
+ * @param pixel_format Function which is called to decide what pixel format the output image should be;
+ * it is passed the pixel format of the input image from the ImageProxy, and should return the desired
+ * output pixel format. Two functions always_rgb and keep_xyz_or_rgb are provided for use here.
+ */