depth of the damage
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From: Beho nashed on 18 Jun 2010 12:55 Hello, I have a question, please. If I have a small specimen , and I know the thickness of it. if I know the color of the specimen both sides (same) , can I estimate the depth of the damage, depending on its color. Thanks
From: Walter Roberson on 18 Jun 2010 13:51 Beho nashed wrote: > I have a question, please. If I have a small specimen , and I know the > thickness of it. if I know the color of the specimen both sides (same) , > can I estimate the depth of the damage, depending on its color. Maybe. Are you assuming that the specimen is of uniform composition and thus uniform translucency and that the amount of light reflected or absorbed is then proportional to the thickness of the specimen? Are you using a reflection (illumination is from the top) or transmission (illumination is from the bottom) model? If the specimen is not of uniform composition then the calculation gets more difficult, especially as there would be refraction at all internal boundaries.
From: Beho nashed on 19 Jun 2010 12:07 Walter Roberson <roberson(a)hushmail.com> wrote in message <hvgbrp$ehj$1(a)canopus.cc.umanitoba.ca>... > Beho nashed wrote: > > > I have a question, please. If I have a small specimen , and I know the > > thickness of it. if I know the color of the specimen both sides (same) , > > can I estimate the depth of the damage, depending on its color. > > Maybe. Are you assuming that the specimen is of uniform composition and thus > uniform translucency and that the amount of light reflected or absorbed is > then proportional to the thickness of the specimen? Are you using a reflection > (illumination is from the top) or transmission (illumination is from the > bottom) model? > > If the specimen is not of uniform composition then the calculation gets more > difficult, especially as there would be refraction at all internal boundaries. Hello Walter, It's transmission ( from the bottom ), and it's a uniform specimen. Thanks
From: ImageAnalyst on 19 Jun 2010 12:59 Of course. I'm sure you already know that color is frequently used to assess quality of an object. But it's up to you to specify the color ranges that constitute "good" and "bad" samples. You can do either pass/fail, or a continuous kind of quality measurement number (such as a delta E). Can you post some images? Not that you need images - you can often do color measurement with a colorimeter or spectrophotometer which creates no image at all.
From: ImageAnalyst on 19 Jun 2010 13:01
As far as measuring the depth from the color, your best bet may be to create a depth step wedge calibration standard. You'd have known depths and then measure the color for that depth. Now you have a calibration curve that can be used to look up the depth of any color. |