doubt regards the image

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ajith
ajith 2012-11-8
Sir, I apply levelset to an grayscaleimage after that I save it in the JPG format so it converted into the 3dimension. I used the saved image for the additional steps. but my doubt is
1. The initial grayscale matrix value and the RGB matrix is different I know about that .*I change the result JPG matrix to grayscale image. The initial gray scale Image and the result of the JPG to grayscale image both are same matrix or not*

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Walter Roberson
Walter Roberson 2012-11-8
It depends on how you wrote the JPEG image. JPEG is by default a lossy compressor, so the data you read back from a JPEG image will not necessarily be exactly the same as what you wrote out. You can specifically request lossless JPEG compression instead, in which case the data you get back should be exactly what you wrote.
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Jan
Jan 2012-11-8
@ajith: Remember, that "lossless JPEG" does not mean, that the reconstructed image is identical to the original image. Rounding artifacts can modify the value slightly, but measurable.
Walter Roberson
Walter Roberson 2012-11-8
编辑：Walter Roberson 2012-11-8
lossless JPEG has no rounding. http://en.wikipedia.org/wiki/Lossless_JPEG
This is not the same encoding technique as JPEG with 100% quality.

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