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