El diálogo de canales es el principal interfaz para editar, modificar y administrar sus canales. Los canales tienen un doble propósito. Es por esto que el diálogo se divide en dos partes: la primera parte es para los canales de color, y la segunda es para las máscaras de selección.
Color channels apply to the image and not to a specific layer. Basically, three primary colors are necessary to render all the wide range of natural colors. As other digital software, GIMP uses Red, Green, and Blue as primary colors. The first and primary channels display the Red, Green, and Blue values of each pixel in your image.
Next to the channel name is a thumbnail displaying a grayscale representation of each channel, where white is 100% and black is 0% of the primary color. Alternatively, if your image is not a colored but a Grayscale image, there is only one primary channel called Gray. For an Indexed image with a fixed number of known colors there is also only one primary channel called Indexed.
Then there is an optional channel called Alpha. This channel displays transparency values of each pixel in your image (See Alpha Channel in Glossary). In front of this channel is a thumbnail displaying a grayscale representation of the transparency where white is opaque and visible, and black is transparent and invisible. If you create your image without transparency then the Alpha channel is not present, but you can add it from the Layers dialog menu. Also, if you have more than one layer in your image, GIMP automatically creates an Alpha channel.
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GIMP no soporta los modelos de color CMYK y YUV. |
La imagen derecha está compuesta de tres canales de color (rojo, verde y azul) y del canal alfa para la transparencia. Sobre la imagen derecha la transparencia se muestra como un tablero de ajedrez. En el canal de color, el blanco es siempre blanco porque todos los colores se hayan presentes, y el negro es negro. El sombrero rojo es visible en el canal rojo pero casi invisible en los otros dos canales. Pasa lo mismo con el verde puro y con el azul puro, los que se hayan visibles sólo en sus propios canales, e invisibles en los otros.
Este diálogo es un diálogo empotrable; consulte la Sección 2.3, “Diálogos y empotrables” para obtener ayuda sobre su uso.
Puede acceder:
from the main menu:
→ → ;from the Tab menu in any dockable dialog by clicking on and selecting → .
In the detached windows which exists only if at least one dialog remains open. In this case, you can raise the “Channels” dialog from the main menu: → .
menu, there is a list ofThe channels at the top are the color channels and the optional Alpha channel. They are always organized in the same order and they cannot be removed. In the middle are two lock buttons, that show the lock status for the currently selected channel in the bottom area. The bottom area shows a list of selection masks. Every channel appears in the list with its attributes, including a thumbnail and its name. A right-click in a channel list entry opens the channel context menu.
Above the list of selection mask channels are two check boxes that show the lock attributes state of the currently selected mask channel.
The paintbrush icon shows whether “lock pixels” is enabled (highlighted) for the current channel. When this is enabled, the channel is locked for any action that changes the pixels, meaning there will be no changes done to this channel.
The cross-with-arrows icon shows whether “lock position and size” is enabled (highlighted) for the current channel. When this is enabled, the channel is locked for any action that changes the position or size.
Cada canal se muestra en la lista con sus propios atributos. que son muy similares a los atributos de las capas:
De manera predeterminada cada canal y cada valor de color son visibles. Este se indica con un icono de “ojo abierto”. Pulsando sobre el símbolo del ojo (o el espacio si el canal no es visible) cambiará la visibilidad del canal.
The channels representing selection masks (in the lower part of the channel list) may be grouped using the button with the “chain” symbol. All channels that have the chain enabled will be affected in the same way by operations applied to any one of them.
Primary color channels (the default channels in the upper part of the channel list) may be grouped too. By default, all color channels (and the alpha channel) are selected, their list entries are highlighted. Operations will be performed on all channels. By clicking on a channel list entry you can deactivate this channel. Operations like colorizing a layer will then be applied to the selected (“grouped”) channels only. Clicking on the deactivated list entry will activate the channel again.
A small preview icon represents the effect of the channel. This preview can be enlarged by holding down the left mouse button on it.
The name of the channel, which must be unique within the image. Double-clicking on the name of a selection mask channel will allow you to edit it. The names of the primary channels (Red, Green, Blue, Alpha) can not be changed. Double-clicking on the preview icon will open a dialog where you can set all channel attributes.
Atención | |
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Activated channels appear highlighted in the dialog. If you click on a channel in the list you toggle activation of the corresponding channel. Disabling a color channel red, blue, or green has severe consequences. For instance if you disable the blue channel, all pixels from now on added to the image will not have a blue component, and so a white pixel will have the yellow complementary color. |
Below the channel list is a set of buttons allowing you to perform some basic operations on channel list.
This creates a new channel. A dialog will open where you can set the Channel name, the Color tag, the channel attributes and lock attributes, and finally the Opacity and color used for the mask in the image window. A click on the color button displays the GIMP color selector where you can change the mask color. If you press the Shift key while clicking the button, the New Channel Dialog will not be opened. Instead the new channel will be created with the same settings as used previously. This new channel is a channel mask (a selection mask) applied over the image. See Selection Mask
Only available for selection masks: this moves the selected channels up in the list. Press Shift key to move the channel to the top of the list.
This moves selected channels down in the list. Press the Shift key to move the channel to the bottom of the list.
This creates a copy of the active channels. The name of the new channel is suffixed with a number.
Sugerencia | |
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You can also duplicate color channels or the Alpha channel. It's an easy way to keep a copy of them and to use them later as a selection in an image. |
This transforms the selected channel to become a selection. By default the selection derived from channels replaces the active selection. You can change this by using control keys.
Shift: the selection derived from a channel is added to the active selection. The final selection is merged from both.
Ctrl: the final selection is the subtraction of the selection derived from a channel from the active selection.
Shift+Ctrl: the final selection is the intersection of the selection derived from a channel with the active one. Only the selected parts common to both are kept.
Only available for selection masks: this deletes the selected channels.
You can get the channel context menu by right clicking on a channel. Several of the operations on channels are also available through buttons at the bottom of the channels list. Those operations are documented there.
Consulte la Gestión de canales.
Only available for selection masks. Here you can change the Channel name, the Color tag, the channel attributes and lock attributes, and finally the Opacity and color used for the mask in the image window. A click on the color button displays the GIMP color selector where you can change the mask color.
Only available for selection masks. This allows you to assign a color tag to a channel. If you have a lot of channels this can make it easier to identify them by giving related channels the same color tag. To remove the color tag choose None.
The selection derived from a channel replaces the previously active selection.
The selection derived from a channel is added to the active selection. The final selection is merged from both.
The final selection is the subtraction of the selection derived from a channel from the active selection.
The final selection is the intersection of the selection derived from a channel with the active one. Only the selected parts common to both are kept.
Los canales se pueden usar para guardar y restaurar sus selecciones. En el diálogo de canales puede ver una miniatura que representa la selección. Las máscaras de selección son una manera gráfica de construir selecciones en un canal de nivel gris en donde los píxeles blancos se seleccionan y los píxeles negros no se seleccionan. Por lo tanto los píxeles grises se seleccionan parcialmente. Puede considerarlos como un difuminado de la selección, una transición suave entre seleccionado y no seleccionado. Es importante evitar el efecto de pixelado cuando rellena una selección o cuando borra su contenido después de aislar un sujeto de su fondo.
Hay varias maneras de inicializar una máscara de selección.
From the main menu
→ if there is an active selection.In the image window the bottom-left button creates a Quick Mask; the content will be initialized with the active selection.
Desde el diálogo de canales, cuando pulsa sobre el botón Canal nuevo o desde el menú contextual. Una vez creada, la máscara de selección aparece en el diálogo de canales, con el nombre “Copia de máscara de selección”, seguido de un número. Puede cambiarlo desde el menú contextual que obtiene pulsando con el derecho sobre el canal.
Once the channel is initialized, selected (highlighted in blue), visible (eye-icon in the dialog), and displayed as you want (color and opacity attributes), you can start to work with all the paint tools. The colors used are important. If you paint with some color other than white, gray, or black, the color Value (luminosity) will be used to define a gray (medium, light, or dark). When your mask is painted, you can transform it to a selection by clicking on the button (Channel to Selection) or from the context menu.
También puede trabajar las máscaras de selección con otras herramientas, no sólo con las herramientas de pintar. Por ejemplo, puede usar las herramientas de selección para rellenar áreas con degradados o con patrones. Añadiendo varias máscaras de selección a la lista puede componer fácilmente selecciones muy complejas. Se puede decir que una máscara de selección es a una selección lo que una capa es a una imagen.
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Una vez que la máscara de selección está activada, trabaja sobre ésta y no sobre la imagen. Para volver a trabajar en la imagen, debe desactivar todas las máscaras de selección. Tampoco olvide ocultar las máscaras desactivando el icono con forma de ojo. También compruebe que todos los canales RGB y alfa estén activados y visibles en la imagen. |
A Quick Mask is a Selection Mask intended to be used temporarily to paint a selection. Temporarily means that, unlike a normal selection mask, it will be deleted from the channel list after its transformation to selection. The selection tools sometimes show their limits when they have to be used for doing complex drawing selection, as progressive. In this case, using the Quick Mask is a good idea which can give very good results.
The Quick Mask can be activated in different ways:
From the main menu:
→ .Pulsando el botón de la parte inferior izquierda mostrado en rojo en la captura de pantalla.
Usando el atajo Mayús+Q.
Para iniciar una Máscara rápida, pulse el botón de la parte inferior izquierda en la ventana de la imagen. Si se activa una selección en su imagen, su contenido aparece sin cambios mientras el borde se cubre con un color rojo translúcido. Otra pulsación en el botón de la parte inferior izquierda desactivará la máscara rápida.
From the channel dialog you can double click on the name or the thumbnail to edit the QMask attributes. Then you can change the Opacity and its filling color. At every moment you can hide the mask by clicking on the eye icon in front of the QMask.
La máscara se codifica en tonos medios, así que debe usar el blanco o el gris para reducir el área limitada por la máscara y el negro para incrementarla. El área pintada en gris claro o oscuro serán áreas de transición de la selección como difuminadas. Cuando su máscara está lista, pulse otra vez sobre el botón de la parte inferior izquierda en la ventana de la imagen y la máscara rápida se quitará de la lista del canal y se convertirá en una selección.
La propuesta de la máscara rápida es pintar un selección y sus transiciones con las herramientas de pintura sin preocuparse con la gestión de las mascaras de selección. Es una buena manera de aislar un sujeto de una imagen porque una vez que se ha hecho la selección sólo tiene que quitar su contenido (o a la inversa si el sujeto está en la selección).
Descripción
Screenshot of the image window with activated Quick Mask. As long as the Quick Mask is activated, all operations are done on it. A gradient from black (left) to white (right) has been applied to the mask.
The Quick Mask is now disabled. The selection occupies the right half part of the image (marching ants) because the limit of the selection is at the middle of the gradient.
Ahora se añade un trazo a la selección habilitada. El degradado, aunque no es visible, permanece activo en la imagen, en las áreas seleccionadas y en las no seleccionadas.
After the Quick Mask Button is pressed, the command generates a temporary 8-bit (0-255) channel, on which the progressive selection work is stored. If a selection is already present the mask is initialized with the content of the selection. Once Quick Mask has been activated, the image is covered by a red semi-transparent veil. This one represents the non-selected pixels. Any paint tool can be used to create the selection on the Quick Mask. They should use only grayscale color, conforming the channel properties, white enabling to define the future selected place. The selection will be displayed as soon as the Quick Mask will be toggled but its temporary channel will not be available anymore.
Sugerencia | |
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To save in a channel the selection done with the Quick Mask select in the main menu → . |
Abrir una imagen o comenzar un documento nuevo.
Activate the Quick Mask using the left-bottom button in the image window. If a selection is present the mask is initialized with the content of the selection.
Choose a drawing tool and use it with grayscale colors on the Quick Mask.
Deactivate the Quick Mask using the left-bottom button in the image window.