File:Quilt design as 46x46 uncompressed GIF.gif

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Quilt_design_as_46x46_uncompressed_GIF.gif ‎(46 × 46 pixels, file size: 3 KB, MIME type: image/gif)

Summary

An example of an uncompressed GIF image. See encoding details below.

Licensing

Encoding details

Size: 46 × 46 pixels, 128 colors. Format: Uncompressed GIF with 7-bit symbols (8-bit codes), packed 1 raster line per sub-block, with an initial CLEAR code at the beginning of each raster line. The image data begins with the "LZW minimum code size" of 7, indicating that the symbols (color table indices) are seven-bit values coded as 8-bit codes. (7-bit color indices are used as the color table has only 128 entries.) This is followed by 46 sub-blocks of image data, one sub-block per raster line, each 48 bytes long. Each sub-block begins with a byte giving the number of data bytes (47 = 2FH), followed by the CLEAR code (80H), followed by the color indices for the 46 pixels in the given raster line, one pixel per byte. The 46 raster sub-blocks are followed by a two-byte sub-block with the STOP code (length byte 01 plus STOP code 81H), followed by the terminating null sub-block (00). -- <a href="https://en.wikipedia.org/wiki/User:Elphion" class="extiw" title="en:User:Elphion">Elphion</a> (<a href="https://en.wikipedia.org/wiki/User_talk:Elphion" class="extiw" title="en:User talk:Elphion">talk</a>) 01:28, 24 May 2011 (UTC)

Each byte of the file is shown below by its hexadecimal value. The first 9 lines as for a normal gif are: the header, Logical Screen Descriptor and a 128-color table . The rest is image data with one byte (never exceeding 7FH) for each pixel.
The image data is arranged in blocks each consisting of:
  • 2FH means there are 47 bytes to follow (Visible at center column of the listing below)
  • 80H is a CLEAR code These periodic CLEAR codes prevent the unintended decoding progressing from 8-bit to 9-bit codes.
  • An image line of 46 pixels.
As a result of the listing width equalling one image line, the image outline can be seen in the data. <a href="https://en.wikipedia.org/wiki/User:Cuddlyable3" class="extiw" title="en:User:Cuddlyable3">Cuddlyable3</a> (<a href="https://en.wikipedia.org/wiki/User_talk:Cuddlyable3" class="extiw" title="en:User talk:Cuddlyable3">talk</a>) 08:43, 24 May 2011 (UTC)

<a href="https://en.wikipedia.org/wiki/Image:Uncompressed_gif_file.PNG" class="extiw" title="en:Image:Uncompressed gif file.PNG">Image:Uncompressed gif file.PNG</a>

Licensing

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File history

Click on a date/time to view the file as it appeared at that time.

Date/TimeThumbnailDimensionsUserComment
current10:13, 5 January 2017Thumbnail for version as of 10:13, 5 January 201746 × 46 (3 KB)127.0.0.1 (talk)An example of an uncompressed GIF image. See encoding details below.<br><h2><span class="mw-headline" id="Licensing">Licensing</span></h2> <h2><span class="mw-headline" id="Encoding_details">Encoding details</span></h2> <p>Size: 46 × 46 pixels, 128 colors. Format: Uncompressed GIF with 7-bit symbols (8-bit codes), packed 1 raster line per sub-block, with an initial CLEAR code at the beginning of each raster line. The image data begins with the "LZW minimum code size" of 7, indicating that the symbols (color table indices) are seven-bit values coded as 8-bit codes. (7-bit color indices are used as the color table has only 128 entries.) This is followed by 46 sub-blocks of image data, one sub-block per raster line, each 48 bytes long. Each sub-block begins with a byte giving the number of data bytes (47 = 2F<sub>H</sub>), followed by the CLEAR code (80<sub>H</sub>), followed by the color indices for the 46 pixels in the given raster line, one pixel per byte. The 46 raster sub-blocks are followed by a two-byte sub-block with the STOP code (length byte 01 plus STOP code 81<sub>H</sub>), followed by the terminating null sub-block (00). -- <a href="https://en.wikipedia.org/wiki/User:Elphion" class="extiw" title="en:User:Elphion">Elphion</a> (<a href="https://en.wikipedia.org/wiki/User_talk:Elphion" class="extiw" title="en:User talk:Elphion">talk</a>) 01:28, 24 May 2011 (UTC) </p> <dl> <dd>Each byte of the file is shown below by its hexadecimal value. The first 9 lines as for a normal gif are: the header, Logical Screen Descriptor and a 128-color table . The rest is image data with one byte (never exceeding 7F<sub>H</sub>) for each pixel.</dd> <dd>The image data is arranged in blocks each consisting of: <dl><dd><ul> <li>2F<sub>H</sub> means there are 47 bytes to follow (Visible at center column of the listing below)</li> <li>80<sub>H</sub> is a CLEAR code These periodic CLEAR codes prevent the unintended decoding progressing from 8-bit to 9-bit codes.</li> <li>An image line of 46 pixels.</li> </ul></dd></dl> </dd> <dd>As a result of the listing width equalling one image line, the image outline can be seen in the data. <a href="https://en.wikipedia.org/wiki/User:Cuddlyable3" class="extiw" title="en:User:Cuddlyable3">Cuddlyable3</a> (<a href="https://en.wikipedia.org/wiki/User_talk:Cuddlyable3" class="extiw" title="en:User talk:Cuddlyable3">talk</a>) 08:43, 24 May 2011 (UTC)</dd> </dl> <a href="https://en.wikipedia.org/wiki/Image:Uncompressed_gif_file.PNG" class="extiw" title="en:Image:Uncompressed gif file.PNG">Image:Uncompressed gif file.PNG</a>
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