30-08-2014, 04:11 PM
Development of Image Processing System Based on DSP and FPGA
Development of Image.pdf (Size: 467.3 KB / Downloads: 11)
Abstract
Real-time image processing system is widely used in
many field, it is required to have high speed. In order to satisfy
the demand, an image processing system structure based on
DSP and FPFA is presented, that is DSP is used as advanced
image processing unit and FPGA as logic unit for image
sampling and display. The hardware configuration and working
principle is introduced firstly, and then some key problems
which include of image data stored mode, color space
conversion and image transmission based on EDMA are
described. Finally the program flowchart for developing image
processing software is given. The developed system can
acquire image, display image and make some image processing
operations which include of geometry transform, orthographic
transform, operations based on pixels, image compression and
color space conversion. The developed system can meet the
real-time requirement and has been used in our teaching.
Keywords: real-time image processing, digital signal
processing (DSP), field programmable gate array (FPGA),
expanded direct memory access (EDMA)
Introduction
Image processing has been used in many fields,
such as industry, military, medical image processing
and so on. But most of the system is developed based
on PC, it can’t meet the requirement for real-time and
high speed in some occasions, so the image processing
and transmission system is increasingly developed
along with the development of electronic technique,
especially DSP and FPGA[1,2]. This paper introduces
an image processing system based on DSP and FPGA.
In the system the TMS320c6713 DSP is used as
advanced image processing and FPGA as logic unit This paper is organized as follows: section 2 first
introduces the hardware configuration and its working
principle of the system, which include of the
designing idea, the image data stored mode and the
color space. The image transmission method between
DSP and FPGA is discussed in section 3. Section 4
gives the program flowchart for developing the image
processing software based on the hardware. Finally
the paper is concluded in section
for image sampling and display
Hardware Configuration and Working Principle of the System
hardware configuration
For real-time image processing system, it needs
high speed because of mass image data, so we can
use DSP to solve this problem. On the other hand,
FPGA has capable of flexible logic control, large
memory and fast executing speed. So the real-time
image processing system can be constituted by the
combination of DSP and FPGA, that is DSP is used as
executing image processing algorithms and FPGA as
logic control unit for image sampling and display.
According to this idea, the developed image
processing is shown in Fig.1.The system is composed
of TMSC6713 DSP board, video board, CCD camera
and VGA display.
(1) CCD camera is used as capturing image.
(2) TMSC6713 DSP board is used as executing
image processing algorithms. The CPU on the board is
TI DSP chip TMSC6713 which is a high performance
float digital signal processor with 255MHz.There are
1Mbits RAM, 8Mbytes with 32bit exterior expanded
memory SDRAM, 512Kbytes Flash, 4 user accessible
LEDs and 4 DIP switches.
system working principle
The system working involves image samples,
image store, image transmission, image processing
and image display. They are described detailed as
follows:
(1) Image acquisition is obtained by CCD camera.
The output of the CCD camera is analog signals of
PAL SEAM, it is transformed to digital image signals
with YUV4:2:2 format by video decoding chip
SA7111.
(2) Image transmission between DSP and FPGA
is gotten through EDMA method. The video data are
first stored into OUTFIFO in FPGA, at the same time
DSP is noticed to take away one row data from FIFO
by interrupt signal caused by synchronization signal.
After the image data are processed by DSP, they
should be sent to video board. The transmission
method is EDMA, the detail of this method will be
discussed in section 3.
Image Transmission Based on EDMA
On considering the speed, EDMA method is used
to transmit image between DSP and FPGA. It is a
peculiar access way for C671X and there are 16
channels for C6713. The image data can be
transmitted directly by EDMA controller but not CPU.
EDMA controller include of four parts[4]: (1) event
and interrupt handle register; (2) event encoder; (3)
parameters RAM; (4) hardware address generator. The
EDMA event is captured by event register and it can
be distinguished by event encoder if there are many
events occurring at the same time. The transmission
parameters are stored at parameters RAM and are sent
to hardware address generator to generate the
addresses for reading and writing operations.
Program Flowchart and the Software Function
The reset button S2 in video board is used to
control the image sampling, a frame image can be got
when it is pressed. The 0th position of SW1 switch in
DSP board is used to start de DSP program for
processing the acquired image.
Fig.4 gives the program flowchart for developing
image processing software. From Fig.4, we can see
that all the processes except the algorithms for image
processing are the same. So the software development
is to write the image processing program. The
functions of the developed software are as follows:
(1) image geometry transform, which include of
transforms of mirror, translation, zoom and rotation.
(2) image orthographic transform, which include
Conclusions
The proposed image processing based on DSP
and FPGA has the advantages of high speed, powerful different level algorithms and large flexibility for
expanding the system. It can meet the requirements
for real-time image processing system
image processing capability of easily implementing