Misplaced Pages

Adam7 algorithm: Difference between revisions

Article snapshot taken from Wikipedia with creative commons attribution-sharealike license. Give it a read and then ask your questions in the chat. We can research this topic together.
Browse history interactively← Previous editNext edit →Content deleted Content addedVisualWikitext
Revision as of 11:36, 29 October 2005 editSmyth (talk | contribs)Extended confirmed users, Pending changes reviewers11,815 edits Link to Interlace (bitmaps)← Previous edit Revision as of 04:36, 2 November 2005 edit undoJshadias (talk | contribs)1,179 editsNo edit summaryNext edit →
Line 12: Line 12:
'''Adam7''' is the ] ] specified for use in ] images. An interlaced PNG image is broken into seven subimages, which are defined by replicating the following 8x8 pattern on the right across the full image. The subimages are stored in the PNG file in numerical order. '''Adam7''' is the ] ] specified for use in ] images. An interlaced PNG image is broken into seven subimages, which are defined by replicating the following 8x8 pattern on the right across the full image. The subimages are stored in the PNG file in numerical order.


Adam7 is a 2D interlacing scheme unlike the 1D scheme used in interlaced ]. This means the percieved quality of the image and the readablity of text in the image rises much faster in the early passes than with GIF interlacing (). Adam7 is a ] interlacing scheme, unlike the 1D scheme used in an interlaced ]. This means the perceived quality of the image and the readablity of text in the image rises much faster in the early passes than with GIF interlacing ().


==Interesting points of note== ==Interesting points of note==

Revision as of 04:36, 2 November 2005

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

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 the following 8x8 pattern on the right across the full image. The subimages are stored in the PNG file in numerical order.

Adam7 is a 2D interlacing scheme, unlike the 1D scheme used in an interlaced GIF. This means the perceived quality of the image and the readablity of text in the image rises much faster in the early passes than with GIF interlacing (demo animation).

Interesting points of note

  • 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

History

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

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

Stub icon

This computer graphics–related article is a stub. You can help Misplaced Pages by expanding it.

Category: