### 4.8. Editor de selección

El comando Editor de selección muestra la ventana del diálogo “Editor de selección”. Este diálogo muestra la selección activa en la imagen actual y le da un acceso fácil a los comandos relacionados con la selección. Realmente, no tiene por fin editar las selecciones directamente, pero si está trabajando sobre una selección, es cómodo tener a mano todos los comandos relacionados, es más fácil pulsar sobre un botón que buscar comandos en el árbol de comandos de la barra de menú. El “Editor de selección”, tambien, ofrece algunas opciones avanzadas para el comando “A la ruta”.

#### 4.8.1. Activar el comando

You can access this command from the main menu through Select → Selection Editor.

#### 4.8.2. Descripción de la ventana del diálogo “Editor de selección”

Figura 16.19. La ventana del diálogo “Editor de selección”

Los botones

  La ventana del diálogo “Editor de selección” tiene algunos botones que puede usar para acceder cómodamente a los comandos de selección:

  - The Select All button.

  - The Select None button.

  - The Select Invert button.

  - The Save to Channel button.

  - The To Path button. If you hold the Shift key while clicking on this button, the Advanced Settings dialog is displayed. Please see the next section for details about these options.

  - The Stroke Selection button.

La ventana de muestra

  En la ventana de muestra, las áreas seleccionadas de la imagen son blancas, las no seleccionadas negras, y las áreas parcialmente seleccionadas en niveles de grises. Pulsar sobre esta ventana funciona como seleccionar por color. Vea el siguiente ejemplo.

Figura 16.20. Ejemplo de pulsar en la ventana de muestra del “Editor de selección”

Selection Editor window after clicking.

Image with the resulting selection applied.

#### 4.8.3. The “Selection to Path Advanced Settings” dialog

Figura 16.21. La ventana del diálogo “Configuración avanzada”

El diálogo “Configuración avanzada de selección a ruta”, que obtiene al pulsar Mayús sobre el botón Selección a ruta, contiene un número de opciones, la mayoría las puede configurar con un deslizador o una caja de texto. También hay una caja de control. Estas opciones las usan principalmente los usuarios avanzados. Son:

Align Threshold

  If two endpoints are closer than this value, they are made to be equal.

Corner Always Threshold

  If the angle defined by a point and its predecessors and successors is smaller than this, it is a corner, even if it is within Corner Surround pixels of a point with a smaller angle.

Corner Surround

  Number of points to consider when determining if a point is a corner or not.

Corner Threshold

  If a point, its predecessors, and its successors define an angle smaller than this, it is a corner.

Error Threshold

  Amount of error at which a fitted spline[6] is unacceptable. If any pixel is further away than this from the fitted curve, the algorithm tries again.

Filter Alternative Surround

  A second number of adjacent points to consider when filtering.

Filter Epsilon

  If the angles between the vectors produced by Filter Surround and Filter Alternative Surround points differ by more than this, use the one from Filter Alternative Surround.

Filter Iteration Count

  The number of times to smooth the original data points. Increasing this number dramatically, to 50 or so, can produce vastly better results. But if any points that “should” be corners aren't found, the curve goes wild around that point.

Filter Percent

  To produce the new point, use the old point plus this times the neighbors.

Filter Secondary Surround

  Number of adjacent points to consider if Filter Surround points defines a straight line.

Filter Surround

  Number of adjacent points to consider when filtering.

Keep Knees

  This check box says whether or not to remove “knee” points after finding the outline.

Line Reversion Threshold

  If a spline is closer to a straight line than this value, it remains a straight line, even if it would otherwise be changed back to a curve. This is weighted by the square of the curve length, to make shorter curves more likely to be reverted.

Line Threshold

  How many pixels (on the average) a spline can diverge from the line determined by its endpoints before it is changed to a straight line.

Reparametrize Improvement

  If reparameterization doesn't improve the fit by this much percent, the algorithm stops doing it.

Reparametrize Threshold

  Amount of error at which it is pointless to reparameterize. This happens, for example, when the algorithm is trying to fit the outline of the outside of an “O” with a single spline. The initial fit is not good enough for the Newton-Raphson iteration to improve it. It may be that it would be better to detect the cases where the algorithm didn't find any corners.

Subdivide Search

  Percentage of the curve away from the worst point to look for a better place to subdivide.

Subdivide Surround

  Number of points to consider when deciding whether a given point is a better place to subdivide.

Subdivide Threshold

  How many pixels a point can diverge from a straight line and still be considered a better place to subdivide.

Tangent Surround

  Number of points to look at on either side of a point when computing the approximation to the tangent at that point.

[6] “Spline” is a mathematical term for a function which defines a curve by using a series of control points, such as a Bézier curve.

See Wikipedia for more information.

4.7. Selection From Paths |  | 4.9. Difuminado

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