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4 | Introduction to the TIFF Documentation | |
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7 | <BODY BGCOLOR=white> | |
8 | <FONT FACE="Arial, Helvetica, Sans"> | |
9 | <H1> | |
10 | <IMG SRC=images/strike.gif WIDTH=128 HEIGHT=100 ALIGN=left HSPACE=6> | |
11 | Introduction to the TIFF Documentation | |
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13 | ||
14 | ||
15 | <P> | |
16 | The following definitions are used throughout this documentation. | |
17 | They are consistent with the terminology used in the TIFF 6.0 specification. | |
18 | ||
19 | <DL> | |
20 | <DT><I>Sample</I> | |
21 | <DD>The unit of information stored in an image; often called a | |
22 | channel elsewhere. Sample values are numbers, usually unsigned | |
23 | integers, but possibly in some other format if the SampleFormat | |
24 | tag is specified in a TIFF | |
25 | <DT><I>Pixel</I> | |
26 | <DD>A collection of one or more samples that go together. | |
27 | <DT><I>Row</I> | |
28 | <DD>An Nx1 rectangular collection of pixels. | |
29 | <DT><I>Tile</I> | |
30 | <DD>An NxM rectangular organization of data (or pixels). | |
31 | <DT><I>Strip</I> | |
32 | <DD>A tile whose width is the full image width. | |
33 | <DT><I>Compression</I> | |
34 | <DD>A scheme by which pixel or sample data are stored in | |
35 | an encoded form, specifically with the intent of reducing the | |
36 | storage cost. | |
37 | <DT><I>Codec</I> | |
38 | <DD>Software that implements the decoding and encoding algorithms | |
39 | of a compression scheme. | |
40 | </UL> | |
41 | ||
42 | <P> | |
43 | In order to better understand how TIFF works (and consequently this | |
44 | software) it is important to recognize the distinction between the | |
45 | physical organization of image data as it is stored in a TIFF and how | |
46 | the data is interpreted and manipulated as pixels in an image. TIFF | |
47 | supports a wide variety of storage and data compression schemes that | |
48 | can be used to optimize retrieval time and/or minimize storage space. | |
49 | These on-disk formats are independent of the image characteristics; it | |
50 | is the responsibility of the TIFF reader to process the on-disk storage | |
51 | into an in-memory format suitable for an application. Furthermore, it | |
52 | is the responsibility of the application to properly interpret the | |
53 | visual characteristics of the image data. TIFF defines a framework for | |
54 | specifying the on-disk storage format and image characteristics with | |
55 | few restrictions. This permits significant complexity that can be | |
56 | daunting. Good applications that handle TIFF work by handling as wide | |
57 | a range of storage formats as possible, while constraining the | |
58 | acceptable image characteristics to those that make sense for the | |
59 | application. | |
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61 | ||
62 | <P> | |
63 | <HR> | |
64 | ||
65 | Last updated: $Date: 1999/08/09 20:21:21 $ | |
66 | ||
67 | </BODY> | |
68 | </HTML> |