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Re: Re: comparing two images and detecting differences

by bean (Monk)
on Jan 05, 2004 at 21:39 UTC ( #318947=note: print w/replies, xml ) Need Help??


in reply to Re: comparing two images and detecting differences
in thread comparing two images and detecting differences

I think comparing edges only may be the key (excellent link, JoshuaD). The edges should capture the features of the coins being compared. Simply comparing images will not work - here's why.


The actual (raised) features of the coin - a capital "I" followed by a capital "T".
++++++++++++++++++++ ++++++++++++++++++++ ++######++++######++ ++++##++++++++##++++ ++++##++++++++##++++ ++++##++++++++##++++ ++######++++++##++++ ++++++++++++++++++++ ++++++++++++++++++++

Here's how the coin would photograph lit from the lower left. Legend: "+" for the metal's "normal" color, "_" for highlights, and "#" for shadows.
++++++++++++++++++++ ++######++++######++ +_++++++#++_++++++#+ ++__++__++++__++__++ +++_++#++++++_++#+++ ++##++##+++++_++#+++ +_++++++#++++_++#+++ ++______++++++__++++ ++++++++++++++++++++

Here's how the coin would photograph lit from the lower right.
++++++++++++++++++++ ++######++++######++ +#++++++_++#++++++_+ ++__++__++++__++__++ +++#++_++++++#++_+++ ++##++##+++++#++_+++ +#++++++_++++#++_+++ ++______++++++__++++ ++++++++++++++++++++

And here's how it would photograph lit dead on.
____________________ __######____######__ _#______#__#______#_ __##__##____##__##__ ___#__#______#__#___ __##__##_____#__#___ _#______#____#__#___ __######______##____ ____________________

The edges for all three images would (I think) all look like the last image.

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