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Guide to Computer forensics and investigations - Chapter 8: Recovering graphics files

This chapter begins with an over-view of computer graphics and data compression, and then explains how to locate and recover graphics files based on information stored in file headers. You learn how to identify and reconstruct graphics file fragments, analyze graphics file headers, and repair damaged file headers. | Chapter 8 Recovering Graphics Files Guide to Computer Forensics and Investigations Fifth Edition Guide to Computer Forensics and Investigations, Fifth Edition Objectives Describe types of graphics file formats Explain types of data compression Explain how to locate and recover graphics files Describe how to identify unknown file formats Explain copyright issues with graphics Guide to Computer Forensics and Investigations, Fifth Edition Recognizing a Graphics File Graphic files contain digital photographs, line art, three-dimensional images, and scanned replicas of printed pictures Bitmap images: collection of dots Vector graphics: based on mathematical instructions Metafile graphics: combination of bitmap and vector Types of programs Graphics editors Image viewers Guide to Computer Forensics and Investigations, Fifth Edition Understanding Bitmap and Raster Images Bitmap images Grids of individual pixels Raster images - also collections of pixels Pixels are stored in rows . | Chapter 8 Recovering Graphics Files Guide to Computer Forensics and Investigations Fifth Edition Guide to Computer Forensics and Investigations, Fifth Edition Objectives Describe types of graphics file formats Explain types of data compression Explain how to locate and recover graphics files Describe how to identify unknown file formats Explain copyright issues with graphics Guide to Computer Forensics and Investigations, Fifth Edition Recognizing a Graphics File Graphic files contain digital photographs, line art, three-dimensional images, and scanned replicas of printed pictures Bitmap images: collection of dots Vector graphics: based on mathematical instructions Metafile graphics: combination of bitmap and vector Types of programs Graphics editors Image viewers Guide to Computer Forensics and Investigations, Fifth Edition Understanding Bitmap and Raster Images Bitmap images Grids of individual pixels Raster images - also collections of pixels Pixels are stored in rows Better for printing Image quality Screen resolution - determines amount of detail Software contributes to image quality (drivers) Number of color bits used per pixel Guide to Computer Forensics and Investigations, Fifth Edition Understanding Vector Graphics Characteristics of vector graphics Uses lines instead of dots Store only the calculations for drawing lines and shapes Smaller than bitmap files Preserve quality when image is enlarged CorelDraw, Adobe Illustrator Guide to Computer Forensics and Investigations, Fifth Edition Understanding Metafile Graphics Metafile graphics combine raster and vector graphics Example Scanned photo (bitmap) with text (vector) Share advantages and disadvantages of both types When enlarged, bitmap part loses quality Guide to Computer Forensics and Investigations, Fifth Edition Understanding Graphics File Formats Standard bitmap file formats Portable Network Graphic (.png) Graphic Interchange Format (.gif) Joint Photographic Experts Group .