NOTE: for discussion, please use ros-developers list

The REP, in text and slightly-more-readable html format, is attached.

Also note that time to discuss this REP is unfortunately rather tight. Since
sensor_msgs/CameraInfo lives in the common_msgs stack, changes to the
message definition must be finalized by Oct 22, only one week from today. We
can quibble over related issues such as image_geometry API changes after
that point, but I want to reach a consensus on the overall design and
specific message changes as quickly as possible. If you have a stake in
CameraInfo, please take a look as soon as you can.

Cheers,
Patrick

Abstract
========

This REP adds support for binning and alternative distortion models to
sensors_msgs/CameraInfo.  It clarifies the correct interpretation of
region of interest (ROI), including how it interacts with binning and
distortion.

In this REP, sensor_msgs/CameraInfo acquires binning_x and binning_y
fields.  The distortion parameter array D is made variable-length, its
meaning specified by an enum.  This REP clarifies ROI to mean the raw
image region as captured by the camera and introduces a distinction
between raw ROI and rectified ROI.  It adds appropriate new methods to
the camera model classes in image_geometry, the recommended API for
using CameraInfo.