projseminar1

8/6/2019 PROJseminar1

1/23

A Seminar onA Seminar on

Digital Image ProcessingDigital Image Processing UUsing cmos Image Sensorsing cmos Image Sensor

ByBy

Md.Akheel Ahmed 05621A0484Md.Akheel Ahmed 05621A0484

N.Narender Reddy 05621A0485N.Narender Reddy 05621A0485


2/23

AIM OF THE PROJECT:

The aim of the project is the design and construction of an interface

between the CMOS camera and a computer, using the AVR

microcontroller.

The proposed tasks for the project:

Make the AVR Atmega128 and its environment work

Communicate the AVR Atmega128 with the computer

Interfacing CMOS image sensor to AVR Atmega128

Make the camera work and see images in the TV

Read and write the registers of the camera using the I2C protocol

Read a line from the camera and send it to the computer

Read a whole image from the camera and send it to the computerImage processing on the system is done using MATLAB software

Make a little process of the image inside the AVR and send the

result to the computer or color graphical lcd


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BLOCK DIAGRAM:


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The information flows in two ways: on the one hand there are

commands from the computer to the camera to change

different characteristics of it, on the other images from the

camera should be sent to the computer.

The communication between the computer and the AVR

Microcontroller is through the serial port.

The communication between the camera and the

microcontroller is: using the I2Cprotocol to access to the

different registers of the camera and using an 8-bit port to read

the images. In addition the camera will be connected to a TVwith its analog output for debugging purpose.


5/23

AVR MICROCONTROLLER:

The AVR is a Modified Harvard architecture machine with

program and data stored in separate physical memory systems

that appear in different address spaces but having the ability to

read data items from program memory using special

instructions.

AT MEGA 128:

The ATmega128 is a low-power CMOS 8-bit microcontroller

based on the AVR enhanced RISC architecture. By executing

powerful instructions in a single clock cycle, the ATmega128

achieves throughputs approaching 1MIPS perMHz allowing

the systemdesigner to optimize power consumption versus processing

speed.


6/23

FEATURESOFAVR:

RISC / Harvard

Powerful microcontroller designed for small applications

Very low power operation 118 instructions

1 instruction per clock cycle (pipelined)

Register-to-register operation

RISC core with ~100 instructions

Modest clock speeds (4-16 MHz)

8-bit bus, 32 GP 8-bit registers

Intended as single chip solutions

In-circuit programmable Flash(~1000 cycles)

Small amount ofEEPROM and SRAM Single-cycle execution of most instructions

Several on-chip peripherals

(UART, SPI,TWI, ADC, PWM, WDT..)


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8/23

PIN DESCRIPTION:

VCC - Digital supply voltage.

GND - Ground.

Port A (PA7..PA0) - Port A is an 8-bit bi-directional I/O port

with internal pull-up resistors (selected for each

bit). The Port A output buffers have symmetrical drive

characteristics with both high sink and source capability. As

inputs, Port A pins that are externally pulled low will source

current if the pull-up resistors are activated. The Port A pins are

tri-stated when a reset condition becomes active, even if theclock is not running.


9/23

Port B (PB7..PB0) - Port B is an 8-bit bi-directional I/O port


bit). The Port B output buffers have symmetrical drive


inputs, Port B pins that are externally pulled low will source

current if the pull-up resistors are activated. The Port B pins

are tri-stated when a reset condition becomes active, even if

the clock is not running.Port C (PC7..PC0) - Port C is an 8-bit bi-directional I/O port


bit). The Port C output buffers have symmetrical drive


inputs, Port C pins that are externally pulled low will source

current if the pull-up resistors are activated. The Port C pins

are tri-stated when a reset condition becomes active, even if

the clock is not running.


10/23

Port D (PD7..PD0) - Port D is an 8-bit bi-directional I/O port


bit). The Port D output buffers have symmetrical drive


inputs, Port D pins that are externally pulled low will source

current if the pull-up resistors are activated. The Port D pins are

tri-stated when a reset condition becomes active, even if the

clock is not running.Port E (PE7..PE0) - Port E is an 8-bit bi-directional I/O port


bit). The Port E output buffers have symmetrical drive


inputs, Port E pins that are externally pulled low will source

current if the pull-up resistors are activated. The Port E pins are


clock is not running.


11/23

Port F (PF7..PF0) - Port F serves as the analog inputs to the

A/D Converter.

Port F also serves as an 8-bit bi-directional I/O port, if the A/D

Converter is not used. Port pins can provide internal pull-up

resistors (selected for each bit). The Port F output buffers have

symmetrical drive characteristics with both high sink and source

capability. As inputs, Port F pins that are externally pulled low

will source current if the pull-up resistors are activated. ThePort F pins are tri-stated when a reset condition becomes active,

even if the clock is not running. If the JTAG interface is

enabled, the pull-up resistors on pins PF7(TDI), PF5(TMS), and

PF4(TCK) will be activated even if a Reset occurs.

The TDO pin is tri-stated unless TAP states that shift out data

are entered.

Port F also serves the functions of the JTAG interface.


12/23

Port G (PG4..PG0) - Port G is a 5-bit bi-directional I/O port


bit). The Port G output buffers have symmetrical drive

characteristics with both high sink and source capability. Asinputs, Port G pins that are externally pulled low will source

current if the pull-up resistors are activated. The Port G pins are


clock is not running.

The port G pins are tri-stated when a reset condition becomes

active, even if the clock is not running.

RESET - A low level on this pin for longer than the minimum

pulse length will generate a reset, even if the clock is not

running. Shorter pulses are not guaranteed to generate a reset.


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XTAL1 - Input to the inverting Oscillator amplifier and input to

the internal clock operating circuit.

XTAL2 - Output from the inverting Oscillator amplifier.

AVCC - AVCC is the supply voltage pin for Port F and the A/D

Converter. It should be externally connected to VCC, even if the

ADC is not used. If the ADC is used, it should be connected to

VCC through a low-pass filter.

AREF - AREF is the analog reference pin for the A/DConverter.

PEN - PEN is a programming enable pin for the SPI Serial

Programming mode, and is internally pulled high . By holding

this pin low during a Power-on Reset, the device will enter theSPI Serial Programming mode. PEN has no function during

normal operation.


14/23

CMOS IMAGESENSOR:

An image sensor is a device that converts an optical image to

an electric signal. It is used mostly in digital cameras and other

imaging devices.

A CMOS chip is a type of active pixel sensor made using the

CMOS semiconductor process. Extra circuitry next to each

photo sensor converts the light energy to a voltage. Additional

circuitry on the chip converts the voltage to digital data.


15/23

The OV6620 is the image sensor used in the project and is the

main part of it. It is a color camera module with digital output.

It uses a CMOS image sensorOV6620 from Omni vision.

It has a digital video port that supplies a continuous 8/16 bit-

wide image data stream. All the camera functions, such as

exposure, gamma, and gain, white balance, windowing, can be

changed through I2C interface by writing in some registers.


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USART:

Universal Synchronous and Asynchronous serial Receiverand Transmitter

standard I/O device that provides conversions betweenserial and parallel data

provides a basic protocol for serial communication

Speed, framing, error control


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AVR USART:

UART or USART is a standard I/O device

The ATMega32 has a USART integrated on-chip, producinglogic signals for RS232 communication

The microcontroller will only produce +/- Vcc, which is

typically 5V; RS232 specifies +/-12V.The STK-500 includes a level converter between the serial

connector and the microcontroller pins.


18/23

USART COMPONENTS:

Transmitter

Manages stream of bits for each byte

Receiver

Manages receipt of bits and assembly into byte

ClockGenerator

Allows the USART to operate in synchronous or

asynchronous modes


19/23

IMAGE PROCESSING:

A method for adjusting the color reproduction of a color

image composed of pixels provided in a plurality of color

channels is based on generating a reference image from acombination of the color channels, whereby each spatial

coordinate of the reference image is characterized by a

reference image level.

Channel averages of the color channel values of the pixelsthat correspond to each of at least two different valued

reference image levels are generated.

Specific channel averages are obtained corresponding to a

near white point and a near black point from the channel

averages. The specific channel averages are utilized on a pixel-

by-pixel basis for the respective channels of the digital color

image to produce a processed digital color image having

improved color reproduction.


20/23

A method for processing Bayer images method comprising:

Receiving a raw image from a sensor with Bayer color arrays.

Determining a corresponding dot in the raw image that

corresponds to each pixel in a final image.

Locating color reference pixels in the raw image according to

the corresponding dot.

Selecting interpolation pixels in the raw image according to

the color reference pixels and interpolating color values of theeach pixel in the final image according to color values of the

interpolation pixels.


21/23

BAYERFORMAT:

Color filters used in most single-chip digital image sensors

used in digital cameras, camcorders, and scanners to create a

color image. The filter pattern is 50% green, 25% red and 25%blue, hence is also called RGBG orGRGB.

This Bayer format is processed in MATLAB to obtain true

RGB picture.

To create a full color image, the camera's image processor

calculates, or interpolates, the actual color of each pixel by

looking at the brightness of the colors recorded by it and others

around it.


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All of these calculations are performed in the camera by an

image processor that's similar to the one in desktop computer,

but dedicated to this single task. How well the processor

performs its functions is critical to the quality of images thathave been captured.

ADVANTAGES:

Digital image processing has many advantages over analog

image processing; it allows a much wider range of algorithmsto be applied to the input data, and can avoid problems such as

the build-up of noise and signal distortion during processing.

DISADVANTAGES:

This system has some delay(in seconds) while producing theoutput.

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