Documentation Status

image_transport_plugins: compressed_image_transport | theora_image_transport

Package Summary

Documented

compressed_image_transport provides a plugin to image_transport for transparently sending images compressed as JPEG or PNG.

image_transport_plugins: compressed_depth_image_transport | compressed_image_transport | libtheora | theora_image_transport

Package Summary

Documented

compressed_image_transport provides a plugin to image_transport for transparently sending images encoded as JPEG or PNG.

image_transport_plugins: compressed_depth_image_transport | compressed_image_transport | theora_image_transport

Package Summary

Released Documented

Compressed_image_transport provides a plugin to image_transport for transparently sending images encoded as JPEG or PNG.

image_transport_plugins: compressed_depth_image_transport | compressed_image_transport | theora_image_transport

Package Summary

Released Continuous integration Documented

Compressed_image_transport provides a plugin to image_transport for transparently sending images encoded as JPEG or PNG.

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Overview

compressed_image_transport is a plugin package for image_transport. It enables any node using image_transport classes to publish and subscribe to compressed image topics. Compression format (JPEG or PNG) and quality can be changed on the fly.

Before reading this page, make sure you understand the image_transport package

Tutorials

See image_transport/Tutorials for general instruction on using image_transport. compressed_image_transport is featured in the image_transport tutorial Examining the Simple Image Publisher and Subscriber.

ROS API

Publisher plugin

Published Topics

<base_topic>/compressed (sensor_msgs/CompressedImage)
  • Compressed transport subtopic.

Parameters

Searchable parameters
The plugin searches up the parameter tree starting from the <base_topic> namespace. For example, with topic /image, you could set parameter /compressed_image_transport_jpeg_quality to a global default, then override it for the specific topic by setting /image/compressed_image_transport_jpeg_quality.
<base_topic>/compressed_image_transport_format (string, default: jpeg)
  • Compression format to use, "jpeg" or "png".
<base_topic>/compressed_image_transport_jpeg_quality (int, default: 80)
  • JPEG quality percentile, in the range [1, 100]. Lower values trade image quality for space savings.
<base_topic>/compressed_image_transport_png_level (int, default: 9)
  • PNG compression level, in the range [1, 9]. Higher values trade computation time for space savings.

Parameters

Reconfigurable parameters
Starting in Diamondback, all publisher parameters are dynamically reconfigurable per-topic. See dynamic_reconfigure for details on dynamically reconfigurable parameters.
<base_topic>/compressed/format (string, default: jpeg)
  • Compression format to use, "jpeg" or "png".
<base_topic>/compressed/jpeg_quality (int, default: 80)
  • JPEG quality percentile, in the range [1, 100]. Lower values trade image quality for space savings.
<base_topic>/compressed/png_level (int, default: 9)
  • PNG compression level, in the range [1, 9]. Higher values trade computation time for space savings.

Subscriber plugin

Subscribed Topics

<base_topic>/compressed (sensor_msgs/CompressedImage)
  • Compressed transport subtopic.

Publishing compressed images directly

Some cameras (particularly webcams) output their image data already in JPEG format. When writing a driver for such a camera, a quick and dirty approach is to simply copy the JPEG data into a sensor_msgs/CompressedImage message and publish it on a topic of the form image_raw/compressed. Then any ROS node using image_transport can subscribe to image_raw with transport compressed, just as if image_transport were used on the publisher side. Of course, the other transport topics (including image_raw itself) will not be available.

Wiki: compressed_image_transport (last edited 2012-12-19 19:21:29 by EitanMarderEppstein)