- '-background', 'white', '-layers', 'flatten',
+ '-background', 'white', '-layers', 'flatten', # opaque
+ '-auto-orient', # apply exif rotation
+ '-interlace', 'plane', # progressive
+ '-strip', '-taint', # omit metadata
+ '-sampling-factor', '4:2:0', '-colorspace', 'sRGB', # half chroma