Talk:Alpha compositing

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[edit] Why alpha?

In the German wp a user asked why the alpha channel was called alpha channel. Does anybody has got an idea? --PhilippWeissenbacher 17:51, May 14, 2005 (UTC)

My guess: RGBA color space Mion 16:28, 21 January 2006 (UTC)

I found a reference and added the information to RGBA color space. --130.234.180.167 23:02, 3 July 2006 (UTC)


[edit] Merger

[edit] For

  • Merge it. They're the same thing. Ayavaron 21:12, 10 September 2006 (UTC)
  • Merge it. The information in blending is basically the A Over B formula when B is opaque. Alancnet 10:26, 14 September 2006 (UTC)
  • Merge it. Neither article tells the whole story now. I do, however, think [Alpha Blending] is the better title -- many other uses of "composite" are applied to reversable or decomposable preocesses. I think of blending as producing an inseparable product. Rndmcnlly 23:42, 15 September 2006 (UTC)
  • Merge. In particular, the alpha blending article raises the important point that a single alpha channel is not the only option for this technique. The compositing article should mention this, and discuss the limitations of conventional RGBA compositing, such as inaccuracy in depictions of transparency in composites, especially with refractive or colored transparent elements.

[edit] Against

[edit] Required Details

This article is missing a lot of important information. Before I propose replacement, I'll throw out what I'd like to see included:

  • a separate article, Coverage (Computer Science), talking about representation of partially transparent images
  • a photorealistic example (showing the result of combining at least 3 layers (A over (B over C)))
  • refocus article on the general case of blending pixels, both with arbitrary coverage
  • clarification between discussion of blending whole images and the blending of two specific pixels
  • discussion of different formulations of the compositing operators (mention whether they are associative or not)
  • a small table of all possible operations (T. Porter and T. Duff, "Compositing Digital Images", SIGGRAPH 84, 253-259)
  • a Separate section about implementation that discusses using associativity to allow distribution/parallelization, 0-1-only alpha bitmaps, integer-only representations, lookup table usage, setting up glBlendFunc

-- Rndmcnlly 01:00, 16 September 2006 (UTC)


sep

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