  In this paper, we propose a new interactive compression scheme for
omnidirectional images. This requires two characteristics: efficient
compression of data, to lower the storage cost, and random access ability to
extract part of the compressed stream requested by the user (for reducing the
transmission rate). For efficient compression, data needs to be predicted by a
series of references that have been pre-defined and compressed. This contrasts
with the spirit of random accessibility. We propose a solution for this problem
based on incremental codes implemented by rate-adaptive channel codes. This
scheme encodes the image while adapting to any user request and leads to an
efficient coding that is flexible in extracting data depending on the available
information at the decoder. Therefore, only the information that is needed to
be displayed at the user's side is transmitted during the user's request, as if
the request was already known at the encoder. The experimental results
demonstrate that our coder obtains a better transmission rate than the
state-of-the-art tile-based methods at a small cost in storage. Moreover, the
transmission rate grows gradually with the size of the request and avoids a
staircase effect, which shows the perfect suitability of our coder for
interactive transmission.
