You need to add signals first.

来源: pieq314 于 2007-02-22 10:38:53 [] [博客] [旧帖] [给我悄悄话] 阅读数 : (235 bytes)
回答: Same 由 pieq314 于 2007-02-22 10:09:52

When you superimpose photos, the noise do not add up, but cancel out partially, so that
1/sqrt(9) + 1/sqrt(9) ＋ 1/sqrt(9) = 1 is invalid.

More procisely,

(total noise)^2 = sum of (individual noise)^2



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• numbers? -lilywxc- ♀ 给 lilywxc 发送悄悄话 (281 bytes) () 02/22/2007 postreply 10:48:08

• Noise is random. -pieq314- ♀ 给 pieq314 发送悄悄话 pieq314 的博客首页 (341 bytes) () 02/22/2007 postreply 11:06:46

• i see, thanks! -lilywxc- ♀ 给 lilywxc 发送悄悄话 (0 bytes) () 02/22/2007 postreply 11:08:40

• 回复：Noise is random. -Arakis- ♂ 给 Arakis 发送悄悄话 (422 bytes) () 02/22/2007 postreply 14:14:59

• Yes -pieq314- ♀ 给 pieq314 发送悄悄话 pieq314 的博客首页 (707 bytes) () 02/22/2007 postreply 14:50:01

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