Shuozhong Wang, SCIE, Shanghai University Shuozhong Wang, SCIE, Shanghai University Digital Image Processing Kenneth R. Castleman 2008/2/26 Presentation by S. Wang Kenneth R. Kenneth R. Castleman Castleman 2008/2/26 Presentation by S. Wang Presentation by S. Wang 1 Shuozhong Wang, SCIE, Shanghai University Shuozhong Wang, SCIE, Shanghai University Original image Original image 2 Shuozhong Wang, SCIE, Shanghai University Shuozhong Wang, SCIE, Shanghai University Rotated Rotated 3 Shuozhong Wang, SCIE, Shanghai University Shuozhong Wang, SCIE, Shanghai University Enhanced Enhanced
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Shuozhong Wang, SCIE, Shanghai UniversityShuozhong Wang, SCIE, Shanghai University
Digital Image Processing
Kenneth R. Castleman
2008/2/26
Presentation by S. Wang
Kenneth R. Kenneth R. CastlemanCastleman
2008/2/26
Presentation by S. WangPresentation by S. Wang
1Shuozhong Wang, SCIE, Shanghai UniversityShuozhong Wang, SCIE, Shanghai University
Original imageOriginal image
2Shuozhong Wang, SCIE, Shanghai UniversityShuozhong Wang, SCIE, Shanghai University
RotatedRotated
3Shuozhong Wang, SCIE, Shanghai UniversityShuozhong Wang, SCIE, Shanghai University
EnhancedEnhanced
4Shuozhong Wang, SCIE, Shanghai UniversityShuozhong Wang, SCIE, Shanghai University
SharpenedSharpened
5Shuozhong Wang, SCIE, Shanghai UniversityShuozhong Wang, SCIE, Shanghai University
Zoomed: before processingZoomed: before processing
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Zoomed: after processingZoomed: after processing
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OriginalOriginal
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EnhancedEnhanced
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Detailed comparisonDetailed comparison
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Correction of Geometric DistortionCorrection of Geometric Distortion
Original
Barrel distortion corrected
Final11
Shuozhong Wang, SCIE, Shanghai UniversityShuozhong Wang, SCIE, Shanghai University
Noisy ImageNoisy Image
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FilteredFiltered
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Image Image inpaintinginpainting
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BibliographyBibliography
K. R. Castleman, Digital Image Processing, Prentice Hall, 1998
Gonzalez and Woods, Digital Image Processing, 2nd Edition, Prentice Hall, 2002(电子工业出版社, 2003)
Gonzalez, Woods, and Eddins, Digital Image Processing Using MATLAB, Prentice Hall, 2004(电子
工业出版社, 2005)
阮秋琦,数字图像处理学,电子工业出版社,北京,2001
Shuozhong Wang, SCIE, Shanghai UniversityShuozhong Wang, SCIE, Shanghai University
Part One Part One -- 11
Fundamentals:Images and Digital ProcessingDigitizing and DisplayTerminology
Fundamentals:Fundamentals:Images and Digital ProcessingImages and Digital ProcessingDigitizing and DisplayDigitizing and DisplayTerminologyTerminology
Shuozhong Wang, SCIE, Shanghai UniversityShuozhong Wang, SCIE, Shanghai University
Chapter IChapter I
Images and Digital ProcessingImages and Digital Images and Digital ProcessingProcessing
17Shuozhong Wang, SCIE, Shanghai UniversityShuozhong Wang, SCIE, Shanghai University
Introduction (1)Introduction (1)
What is digital image processing?– Manipulation of images by computer.
Factors that stimulate development of the subject:– Computer: growing performance and declining cost.– Increasing availability of digitizing and display equipment.
• Digital camera, scanner, video acquisition device, …• CRT, LED, printer, …
18Shuozhong Wang, SCIE, Shanghai UniversityShuozhong Wang, SCIE, Shanghai University
Introduction (2)Introduction (2)
Basic elements of digital image processing– Input– Storage– Processor– Output
摄像机
扫描仪 其他输出设备Computer
打印输出
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Terminology (1)Terminology (1)
ImageImage and picturepicture is used interchangeably in this course.
DigitalDigital: related to calculation by numerical methods or by discrete units.
Digital imageDigital image: : a 2D rectangular array of quantized sample values. Only digital images can be processed by computer.– Sampled in equally spaced rectangular grid pattern (raster), and
– Quantized in equal intervals of amplitude.
Digital image processingDigital image processing: the act of subjecting a digital image that is a numerical representation of an object to a series of operations in order to obtain a desired result.
20Shuozhong Wang, SCIE, Shanghai UniversityShuozhong Wang, SCIE, Shanghai University
Terminology (2)Terminology (2)
Generalized imagesGeneralized images:– Non-optical images– Higher dimensional images (including multi-spectral images)– Images produced with non-standard sampling– Images produced with non-standard quantization
Image processingImage processing and image analysisimage analysis:– Image processing takes an image to produce a modified image
for better viewing or some other purposes.– Image analysis takes an image into something other than an
image such as number of object types, size of an object, etc.
Computer graphicsComputer graphics: concerned with generation of images with computer.Computer visionComputer vision: concerned with interpretation of scenes.
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Terminology (3)Terminology (3)
DigitizingDigitizing: the process of converting an image from its original form into digital form.
DisplayDisplay: reverse operation of digitizing, which generates a visible image from a digital image. – Image reconstruction on a screen (volatile)
– Hardcopy (permanent display)
– Image recording
ScanningScanning: sequentially addressing small spots in an image (pixels).
PixelPixel: picture cell, picture element.
22Shuozhong Wang, SCIE, Shanghai UniversityShuozhong Wang, SCIE, Shanghai University
Terminology (4)Terminology (4)
SamplingSampling: measuring the gray level (color) of an image at each pixel location.QuantizationQuantization: Representation of a measured value by an integer (A-D conversion).
sampling quantization23
Shuozhong Wang, SCIE, Shanghai UniversityShuozhong Wang, SCIE, Shanghai University
Terminology (5)Terminology (5)
Global operationGlobal operation: applied equally throughout the image.
Point operationPoint operation: value of output pixel depends only on the corresponding pixel in the input image.
ContrastContrast: magnitude of gray-level difference in an image.
28Shuozhong Wang, SCIE, Shanghai UniversityShuozhong Wang, SCIE, Shanghai University
Image DigitizersImage Digitizers
Equipment for digitizing images turns a computer into an image-processing workstation.– Inexpensive image digitizers make image processing popular.
Topics about image digitizers:– Elements of an image digitizer
• Sampling aperture, to be able to access pixels
• Scanning mechanism, to address pixels
• Light sensor, to measure pixel brightness
• Quantizer, to accomplish A-to-D conversion
• Output storage medium, to store the processed results
– Related physical phenomena (optoelectric effects, deflection, etc.)
– Implementations (CCD, LED, etc.)
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Characteristics of an Image DigitizerCharacteristics of an Image Digitizer
Pixel size and spacing
Image size
Local property measured: transmittance, optical density
of the film, light intensity, etc.
Linearity: determines the accuracy of measurement
Dynamic range of the gray scale
Noise
30Shuozhong Wang, SCIE, Shanghai UniversityShuozhong Wang, SCIE, Shanghai University
Types of Image DigitizersTypes of Image Digitizers
Scanners
Digital cameras
Plug-in cards for image/video grabbing
Shuozhong Wang, SCIE, Shanghai UniversityShuozhong Wang, SCIE, Shanghai University
Chapter 3Chapter 3
Digital Image DisplayDigital Image DisplayDigital Image Display
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IntroductionIntroduction
Basic requirement: the display should not cause degradation to an accurately digitized and properly processed digital image.Gray level resolution:– Human eye can resolve 40 gray levels.– Due to edge enhancement capability of the retina, gray-level
transition must be smaller than 1/40 of the full perceivable range.
Commercial software tools have powerful functions and friendly user-interface for image processing.Skills in using these tools require knowledge of image processing and practical experiences. Examples:– Adobe Photoshop: the most popular software for digital
photograph processing and artistic manipulations– ACD System
• ACDSee: for viewing digital images• ACD Photo Editor
– Microsoft Photo Editor– And many more …
42Shuozhong Wang, SCIE, Shanghai UniversityShuozhong Wang, SCIE, Shanghai University
Special Purpose Image ProcessorsSpecial Purpose Image Processors
These are developed for specific applications, generally having basic processing capabilities and special functions.Examples– Remote sensing image processing system– Document image processing system– Watermarking system for copyright protection
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Development PlatformsDevelopment Platforms
MATLAB– Powerful tool for numerical computation, simulation, visualization,
prototyping, etc.
– Useful in research and development in image processing
Visual C++– Frequently used in developing image processing applications and
commercial products
– Important in transfer research findings into real applications
Hardware implementation of processing algorithms– DSP, ASIC, etc.
– For real time environments
– Combined into other applications and devices
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Digital Processing of ImagesDigital Processing of Images
Continuous Scene
Analog Observation
Digital Processing by
Computer
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Human eye resolutionHuman eye resolution
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Shoulder and ToeShoulder and Toe
Shoulder Toe
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DeDe--nosingnosing
Before processing After processing
Noise elimination algorithm allows decreasingdecreasing noise impact while retaining retaining the sharpness of small details.
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Industrial ApplicationsIndustrial Applications
Detection/recognition of different types of road surface damage
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Remote SensingRemote Sensing
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Medical ImagesMedical Images
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