rosbag Image Decompression With API

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Folks,

My rosbags all have compressed image topics ONLY. I want to grab the images from my rosbag and decompressed them through the rosbag API (or through code, in general). I believe that should be a fast method compered to playing the rosbag and subscribing to the image topics??? If I am not correct about this, then tell me, and I'll just play each rosbag, and decompress images the old ROS fashion way (I have 1600 rosbags, 8 seconds long each)