DIGITAL IMAGE PROCESING

1960

NASA LUNAR AND PLANETARY EXPLORATION

ANALOG DIGITAL

ADC

APPLICATION OF DIGITAL IMAGING

• ULTRASOUND

• DIGITAL RADIOGRAPHY

• NUCLEAR MEDICINE

• CT

• MRI

RADIOGRAPHY - PAST

TODAY

FLUOROSCOPY IN THE PAST

CONVENTIONAL

DIGITAL FLUOROSCOPY

CASTELMAN (1996)

CLASSIFICATION OF THE IMAGES BASED ON THEIR

FORM OR METHOD OF FORMATION

IMAGES

• VISIBLE

• OPTICAL

• NONVISIBLE IMAGES

• MATHEMATICAL

ANALOG IMAGE

CONTINUOUS IMAGES.

ANALOG IMAGERADIOGRAPH- CONTINUOUS DISTRIBUTION OF LIGHT

INTENSITY AS A FUNCTION OF POSITION ON THE RADIOGRAPH

DIGITAL IMAGE

NUMERIC REPRESENTATION OR IMAGES OF OBJECTS

ANALOG TO DIGITAL

ADC

PROCESSING

ANALOG vs DIGITAL

DIGITAL TO ANALOG

DAC

ANALOG PROCESSING

INPUT AND OUTPUT IMAGES ARE BOTH ANALOG

DIGITAL PROCESSING

INPUT AND OUTPUT IMAGES ARE BOTH DISCRETE

IMAGE DIGITIZATION - ADC

• SCANNING

• SAMPLING

• QUANTIZATION

SAMPLING FREQUENCY

LOW SAMPLING ALIASING ARTIFACT

CT- SIGNAL FROM DETECTORS: ANALOG

ANALOG

MRI- SIGNAL FROM DETECTORS: ANALOG

ANALOG

PET- SIGNAL FROM DETECTORS: ANALOG

ANALOG

BASIC DATA AQUSITION SCHEME IN CT

ADC

DETECTORS

P.M. TUBE SOLID STATE

DETECTORS

MATRIX - EYE OF THE BEE?!

DIGITAL RADIOGRAPH

Y

MATRIX

MATRIXIMAGE RECEPTOR

PIXEL RESOLUTION IN MATRIX

4 x 4---16 PIXELS4 x 4 MATRIX

MATRIX

PIXEL

WHAT MATRIX?5 X 4 20 PIXELS

HIGH vs LOW RESOLUTION

SPATIAL RESOLUTION

SPATIAL RESOLUTION

SPATIAL RESOLUTION= FOV/ MATRIXSPATIAL RESOLUTION= FOV/ MATRIX

IMAGE MATRIX SIZES FOR DIFFERENT MODALITIES

• NUCLEAR MEDICINE

• CT

• MRI

• DR

• CR

• 64 X 64

• 256 X 256

• 512 X 512

• 1024 X 1024

• 2048 X 2048

DYNAMIC RANGE:

• THE RANGE OF VALUES OVER WHICH THE SYSTEM CAN RESPOND

HOW MANY DIFFERENT SHADES CAN BE DISPLAYED IN THE PIXEL?

DYNAMIC RANGE

• 1 BIT• 2 BIT• 3 BIT• 4 BIT• 5 BIT

• 2 COLORS• 4 COLORS• 8 COLORS• 16 COLORS• 32 COLORS

2 X BIT

1 BIT

2 BIT

5 BIT

IMAGE MANIPULATION

• WINDOWING

• INVERSION

• IMAGE SHARPENING

WINDOW CENTER (LEVEL) CONTROLS:

IMAGE DENSITY

WINDOW WIDTH CONTROLS:

IMAGE CONTRAST

WINDOWING

WINDOWING

IMAGE INVERSION

IMAGE SHARPENING

RECENT ADVANCEMENTS

VIRTUAL REALITY

CINE

CT ANGIOGRAPHY