1. Image Transport Protocol ITP
(Synopsis)

2. Analysis
The Image Transport Protocol basically aims at faster transfer of JPEG
image files with less redundancy. This protocol reduces the interactive
latency in the image transmission. ITP is designed for the transmission
of JPEG images only because GIF image format is compatible only with
the TCP based in-order delivery of data and GIF images do not allow
its image decoder to format individual data units (ADUs). This protocol
is implemented over User Datagram Protocol (UDP). This enables outof-order delivery of datagrams, and hence unnecessary overhead due
to handshaking is avoided. Thus the quality of the received images is
improved.
In the design of the protocol structure, the header format has been
fixed and various fields in the header have been defined. The default
values of various fields have been set. The size of the datagram has
been formulated. In out-of-order delivery of ADUs, the ADU is being
efficiently accommodated by the application even if it is larger than a
single un-fragmented packet. The transmission of the ADUs is done
over the User Datagram Protocol (UDP).
In
Receiver
controller
selective
reliability
the
retransmission
is
controlled by the receiving application. The quality of the received
image is improved and the unnecessary overhead generated by the
sender is reduced.
Receiver
controls
the
transmission
and
retransmission
of
the
Application Data Units (ADUs). Hence it is responsible for the loss of
the ADUs, if any. Receiver control strategy is being implemented in

3. order to enable the sender to send the required ADUs, rather than
most of them at irrelevant time intervals. Sender transmits the
Retransmission Time Out information and the receiver uses it during
the various retransmission requests. The receiver does prioritization,
since it is the receiver, which is aware of the required ADUs.
Finally the performance is analysed using various QOS parameters like
transit delay, throughput, Peak Signal to Noise Ratio (PSNR) and it is
being compared with the conventional approach of image transfer
using TCP as base transport layer.
TCP-based Image Transmission Drawbacks
•
High Interactive latency
•
Low Image quality due to reduction of non-bursty transfers.
•
No reliability because of unmodified protocol and image header.
•
Performance evaluations such as Timestamp, Retransmission
Time Out, are not possible.
•
Entire image-file is transmitted due to in-order delivery.

4. Image Transport Protocol
Module Details
Connections & Image Manager
• Takes care of basic JPEG image operations like image reading,
image writing (new image creation) and drawing on the screen.
• Takes care of basic network operations like receiver initialization
and listening, sender initialization and connection request and
data transfer.
Framing
• Framing is dividing the image data into packets based on image
dimensions.
• Each row in the image matrix is encapsulated as a data unit and
each data unit is sent at a time.
Scheduling
• In scheduling, the packets ordering is carried out.
• In TCP scheduling, the receiver waits infinitely for the next
packet if the previous packet is lost. Retransmission request is
continuously sent until the next packet is received.
• In ITP scheduling, the sender continues with the next packet
even if a packet is lost, so that no delays will be there in image
transfer. The lost rows in the received image are reconstructed
during error-concealment.
Error-Concealment
• After the receiver has received the full image using ITP, the
missing parts of the image are reconstructed using neighboring
pixel information.
Analysis and Comparison
• TCP and ITP image transmission are compared using time. ITP
takes less time in transferring the image as it does not waits for
the lost packet to be re-transmitted.
• Image received through TCP and image reconstructed through
ITP will be exactly similar, but still TCP takes more time for
image transmission.