You are currently not logged in! Enter your authentication credentials below to log in. You need to have cookies enabled to log in.
This shows you the differences between two versions of the page.
en:processing:градиент [2012/06/21 11:27] Анна Протопопова created |
en:processing:градиент [2012/06/21 11:27] Анна Протопопова |
||
---|---|---|---|
Line 5: | Line 5: | ||
{{:processing:lena_1.jpg|}} {{:processing:lena_2.jpg|}} | {{:processing:lena_1.jpg|}} {{:processing:lena_2.jpg|}} | ||
- | In general case directional derivative along //X// axis (or //Y// axis) for discrete function can be expressed as {{:processing:grad_1.jpg|}} (or {{:processing:grad_2.jpg|}}), where {{:processing:grad_3.jpg|}} refers to the resultant of discrete functions {{:processing:grad_4.jpg|}} and {{:processing:grad_5.jpg|}} and differentiable function {{:processing:grad_6.jpg|}} (image). There are various calculation algorithms for derivative of two-dimensional discrete function. FemtoScan uses three algorithms: | + | In general case directional derivative along //X// axis (or //Y// axis) for discrete function can be expressed as {{:processing:grad_1.jpg|}} (or {{:processing:grad_2.jpg|}}), where {{:processing:grad_3.jpg|}} refers to the resultant of discrete functions {{:processing:grad_4.jpg|}} and {{:processing:grad_5.jpg|}} and differentiable function {{:processing:grad_6.jpg|}} (image). There are various calculation algorithms for derivative of two-dimensional discrete function. Femtoscan uses three algorithms: |
* Difference algorithm. In this algorithm the //X// (or //Y//) derivative at a point is determined as the difference between values in neighboring points in line (or in column). | * Difference algorithm. In this algorithm the //X// (or //Y//) derivative at a point is determined as the difference between values in neighboring points in line (or in column). | ||
* [[http://en.wikipedia.org/wiki/Prewitt_operator|Prewitt algorithm]]. This algorithm was created by Dr. Judith Prewitt for the most efficient edge detecting in medical images. The derivative at a point is one third from sum of differences between values in neighboring points in the same line, one line higher and one line lower (or in three columns – column with point where derivative is calculated, column to the left and column to the right). | * [[http://en.wikipedia.org/wiki/Prewitt_operator|Prewitt algorithm]]. This algorithm was created by Dr. Judith Prewitt for the most efficient edge detecting in medical images. The derivative at a point is one third from sum of differences between values in neighboring points in the same line, one line higher and one line lower (or in three columns – column with point where derivative is calculated, column to the left and column to the right). |