A bitmap’s image quality on a monitor is governed by resolution, which determines the amount of detail that’s displayed.
In most cases, printing an image converts, or rasterizes, it to print pixels line by line instead of processing the complete collection of pixels. Understanding Bitmap and Raster Images Bitmap images store graphics information as grids of pixels, short for “picture elements.” Raster images are also collections of pixels, but they store pixels in rows to make images easy to print.
However, converting graphics files in this way can change the image quality, as you see in a Hands-On Project at the end of this chapter. If you open a graphics file in a graphics editor that supports multiple file formats, you can save the file in another file format. Each format has different qualities, including the amount of color and compression it uses. When you use a graphics editor or an image viewer, you can open a file in one of many graphics file formats, such as. You use image viewers to open and view graphics files but not change their contents. You use graphics editors to create, modify, and save bitmap, vector, and metafile graphics. You can use two types of programs to work with graphics files: graphics editors and image viewers. Metafile graphics are combinations of bitmap and vector images. Vector graphics are based on mathematical instructions that define lines, curves, text, ovals, and other geometric shapes. Bitmap images are collections of dots, or pixels, in a grid format that form a graphic. A graphics program creates one of three types of graphics files: bitmap, vector, and metafile. You might have used a graphics program, such as Microsoft Paint, Adobe Photoshop, or Gnome GIMP, to create or edit an image. Recognizing a Graphics File Graphics files contain digital photographs, line art, three-dimensional images, and scanned replicas of printed pictures. Copyrights determine the ownership of media, such as images downloaded from a Web site. Steganography involves hiding data, including images, in files. This chapter also explores tools for viewing graphics files you recover and discusses two computer graphics issues: steganography and copyrights.
#Prodiscover basic and image files how to#
You learn how to identify and reconstruct graphics file fragments, analyze graphics file headers, and repair damaged file headers. This chapter begins with an overview of computer graphics and data compression, and then explains how to locate and recover graphics files based on information stored in file headers.
To examine and recover graphics files, you need to understand the basics of computer graphics, including file characteristics, common file formats, and compression methods for reducing file size. Many computer forensics investigations involve graphics, especially those downloaded from the Web and circulated via e-mail.
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