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⚫ '''Adam7''' is the ] ] specified for use in ] images. An interlaced PNG image is broken into seven subimages, which are defined by replicating this 8×8 pattern across the full image.
⚫ <table style="float: right; background: transparent;"><tr><td>

⚫ <center><table style="background: transparent;"><tr><td>
<pre>1 6 4 6 2 6 4 6 <pre>1 6 4 6 2 6 4 6
7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7
Line 9: Line 11:
7 7 7 7 7 7 7 7 7 7 7 7 7 7 7 7
</pre> </pre>
</table> </table></center>
⚫ '''Adam7''' is the ] ] specified for use in ] images. An interlaced PNG image is broken into seven subimages, which are defined by replicating the 8×8 pattern shown on the right across the full image. The subimages are stored in the PNG file in numerical order.


The subimages are then stored in the PNG file in numerical order.
Adam7 is a two-dimensional interlacing scheme, unlike the one-dimensional scheme used in an interlaced ]. This means the perceived quality of the image and the readability of text in the image rises much faster in the early passes than with GIF interlacing.


Adam7 uses seven passes and operates in both dimensions, compared to only four passses in the vertical dimension used by ]. This means the whole image can be perceived much more quickly in the early passes.
==Summary==


⚫ Adam7 is named after Adam M. Costello, who suggested the method on ], ], based on this five-pass scheme that had earlier been proposed by Lee Daniel Crocker:
* Two-dimensional interlacing scheme
* PNG first interlace pass displays 1/64th of the image data
* The GIF format on the other hand displays 1/8th of the image data
* PNG will send 4 passes to GIF's 1st pass


⚫ <center><table style="background: transparent;"><tr><td>
==History==
⚫ <table style="float: right; background: transparent;"><tr><td>
<pre>1 4 2 4 <pre>1 4 2 4
5 5 5 5 5 5 5 5
3 4 3 4 3 4 3 4
5 5 5 5 5 5 5 5
</pre></table> </pre></table></center>
⚫ Adam7 is named after Adam M. Costello, who suggested the method on ], ], based on a very similar five-pass scheme that had earlier been proposed by Lee Daniel Crocker.


==External links== ==External links==
* *


] ]


] ]


{{compu-graphics-stub}}

Revision as of 14:24, 5 August 2006

Adam7 is the interlacing algorithm specified for use in PNG images. An interlaced PNG image is broken into seven subimages, which are defined by replicating this 8×8 pattern across the full image. 

1 6 4 6 2 6 4 6
7 7 7 7 7 7 7 7
5 6 5 6 5 6 5 6
7 7 7 7 7 7 7 7
3 6 4 6 3 6 4 6
7 7 7 7 7 7 7 7
5 6 5 6 5 6 5 6
7 7 7 7 7 7 7 7

The subimages are then stored in the PNG file in numerical order.

Adam7 uses seven passes and operates in both dimensions, compared to only four passses in the vertical dimension used by GIF. This means the whole image can be perceived much more quickly in the early passes.

Adam7 is named after Adam M. Costello, who suggested the method on January 30, 1995, based on this five-pass scheme that had earlier been proposed by Lee Daniel Crocker: 

1 4 2 4
5 5 5 5
3 4 3 4
5 5 5 5

External links

Category: