Figure 9.27.
The screenshot illustrates the Gradients dialog
The Gradients dialog offers a gradient palette which is used to select
a gradient -- a set of colors arranged in a linear scale -- for use
with the Blend tool and numerous
other operations. It also gives you access to several functions for
manipulating gradients. You can select a gradient by clicking on it in
the list: it will then be shown in the Brush/Pattern/Gradient area of
the Toolbox. A few dozen nice gradients come pre-installed with GIMP.
You can create more using the Gradient Editor. General
information about gradients and how they are used in GIMP can be found
in the Gradients
section.
The first four gradients are particular: they reproduce the gradient
between Foreground and background colors of toolbox in different ways.
3.4.1.
Activate Dialog
The Gradients dialog is a dockable dialog; see the section on Dialogs and Docking for help on
manipulating it. It can be activated in several ways:
From the Toolbox menu:
File->Dialogs->Gradients.
From the Toolbox menu:
File->Dialogs->Create New Dock->Brushes, Patterns, and Gradients.
This gives you a dock containing three dialogs, with the
Gradients dialog one of them.
From the Toolbox, by clicking on the current gradient in the
Brush/Pattern/Gradient area.
From an image menu:
Dialogs->Gradients.
From the Tab menu in any dockable dialog:
Add Tab->Gradients.
From the image by using the Ctrl+G shortcut.
3.4.2.
Using the Gradients dialog
The most basic, and most commonly used, operation with the dialog is
simply to click on one of the gradients in the scrollable list, in order
to make it GIMP's current gradient, which will then be used by any
operation that involves a gradient.
If you double-click
on a gradient, you open the Gradient Editor where you will be able to
edit its name. Note, however, that you are only allowed to change the
names of gradients that you have created yourself, not the ones that
come pre-installed with GIMP. If you try to rename a pre-installed
gradient, you will be able to edit the name, but as soon as you hit
return or click somewhere else, the name will revert to its original
value. It is a general rule that you cannot alter the resources that
GIMP pre-installs for you: brushes, patterns, gradients, etc; only ones
that you create yourself.
Grid/List modes
In the Tab menu, you can choose between View as
Grid and View as List.
In Grid mode, the gradients are laid out in a rectangular
array. They look quite dazzling when viewed this way, but it is
not very easy to pick the one you want, because of visual
interference from the neighboring ones. In List mode, the
more usable default, the gradients are lined up vertically, with
each row showing its name.
Note
In the Tab menu, the option Preview Size
allows you to adapt the size of gradient previews to your
liking.
The buttons at the bottom of the dialog allow you to operate on
gradients in several ways:
This creates a new gradient, initialized as a simple grayscale,
and activates the Gradient Editor so that you can alter it.
Gradients that you create are automatically saved in the
gradients
folder of your personal GIMP directory, from which they are
automatically loaded when GIMP starts. (You can change this
folder, or add new ones, using the Preferences dialog.)
Duplicate Gradient
This creates a copy of the currently selected gradient. You will
be able to edit the copy even if you cannot edit the original.
Delete Gradient
This removes all traces of the gradient, if you have permission to
do so. It asks for confirmation before doing anything.
Refresh Gradients
If you add gradients to your personal
gradients
folder by some means other than this dialog, this button causes
the list to be reloaded, so that the new entries will be
available.
The functions performed by these buttons can also be accessed
from the dialog pop-up menu, activated by right-clicking
anywhere in the gradient list. The menu also gives you one
additional function:
Save as POV-Ray...
This allows you to save the gradient in the format used by
the POV-Ray 3D ray-tracing
program.
3.4.3.
Gradient Editor
Revision History
Revision $Revision: 1.23 $
2006-03-02
j.h
Figure 9.28.
The gradient editor
The Gradient Editor allows you to edit the colors in a gradient. It can
only be used on gradients you have created yourself (or on a copy of a
system gradient), not on system gradients that come pre-installed with
GIMP. This is a sophisticated tool that may take a bit of effort to
understand. The concept behind it is that a gradient can be decomposed
into a series of adjoining segments,
with each segment consisting of a smooth transition from the color on
the left edge to the color on the right edge. The Gradient Editor allows
you to pack together any number of segments, with any colors you want for
the left and right edges of each segment, and with several options for the
shape of the transition from left to right.
3.4.3.1.
How to Activate the Gradient Editor
You can activate the Gradient Editor in several ways:
By double-clicking on the gradient stripe in the Gradient
dialog.
From the context menu you get by right clicking on the
selected gradient name.
By clicking on the Edit gradient
button in the Gradient Dialog.
From the Gradient Menu you get by clicking on the small
triangle representing the Tab Menu in the Gradient Dialog.
3.4.3.2.
Display
Name
In the name area, you have the tab menu button (the small
triangle) which opens a menu where you find the Gradient Editor
Menu.
Gradient Display
Below the name, you see the current result of your work if the
Instant update option is checked; else,
changes will appear only when you release the mouse button.
If you simply move the mouse pointer on this display, it works
somewhat as a color-picker. Values of the pointed pixel are
displayed in a rather odd way. Position
is a number given to 3 decimal places, from 0.000 on the left to
1.000 on the right of the whole gradient.
RGB, HSV, Intensity and Opacity
are also a ratio...
If you click-n-drag on display, then only position and RGB data
are displayed. But they are passed on to the Foreground color in
Toolbox and to the four first gradients of the palette.
Range Selection/Control Sliders
Below the gradient display, you see a set of black and white
triangles lined up in row. A segment
is the space between two consecutive black
triangles. Inside each segment is a white triangle, which is used
to “warp”
the colors in the segment, in the same way that the middle slider
in the Levels tool warps the colors there. You can select a
segment by clicking between the two black triangles that define
it. You can select a range of segments by shift-clicking on them.
The selected range always consists of a set of
consecutive
segments, so if you skip over any when shift-clicking, they will
be included automatically. If “Instant update”
is checked, the display is updated immediately after any slider
movement; if it is unchecked, updates only occur when you release
the mouse button.
You can move sliders, segments and selections. If you simply
click-n-drag a slider,
you only move the corresponding transition. By
Click-n-drag on a segment
you can move this segment up to the next triangle. By
Shift+click-n-drag on a segment/selection,
you can move this segment/selection and compress/ dilate next
segments.
Scrollbar
Below the sliders is a scrollbar. This only comes into play if you
zoom in using the buttons at the bottom.
Feedback Area
Below the sliders is an area that initially is blank, but
depending on your actions, helpful hints or feedback messages may
appear here.
Buttons
At the bottom of the dialog appear five buttons:
Save
Clicking this button causes the gradient, in its current
state, to be saved in your personal
gradients
folder, so that it will automatically be loaded the next
time you start GIMP.
Revert
Clicking this button undoes all of your editing. (However,
at the time this is being written, this function is not yet
implemented.)
Zoom Out
Clicking this button shrinks the gradient display
horizontally.
Zoom In
Clicking this button expands the gradient display
horizontally. You can then use the scrollbar to pan the
display left or right.
Zoom All
Clicking this button resizes the display horizontally so
that it fits precisely into the window.
3.4.3.3.
Gradient Editor Menu
Figure 9.29.
The Gradient Editor menu
You can access the Gradient Editor menu either by right-clicking on the
gradient display, or by choosing the top item in the dialog's tab menu.
The menu allows you to set the left and right edge colors for each
segment, and control the transition from one color to the other.
The following commands can be found in the menu:
Left [Right] Endpoint's Color
These options allow you to choose a color for the
respective endpoint using a Color Editor.
Load Left [Right] Color From
Figure 9.30.
The "Load Color From" submenu
These options give you a number of alternative ways of assigning
colors to the endpoints. From the submenu you can choose (assuming
we're dealing with the left endpoint):
Left Neighbor's Right Endpoint
This choice will cause the color of the right endpoint of
the segment neighboring on the left to be assigned to the
left endpoint of the selected range.
Right Endpoint
This choice will cause the color of the right endpoint of
the selected range to be assigned to the left endpoint.
FG/BG color
These choice cause GIMP's current foreground or background
color, as shown in the Toolbox, to be assigned to the
endpoint.
RGBA slots
At the bottom of the menu are 10 "memory slots". You can
assign colors to them using the "Save" menu option described
below. If you choose one of the slots, the color in it will
be assigned to the endpoint.
Save Left [Right] Color To
These options cause the color of the endpoint in question to be
assigned to the "memory slot" selected from the submenu.
Blending Function for Segment/Selection
Figure 9.31.
The Blending Function submenu
This option determines the course of the transition from one
endpoint of the range (segment or selection) to the other, by
fitting the specified type of function to the endpoints and
midpoint of the range:
Linear
Default option. Color varies linearly from one endpoint of
the range to the other.
Curved
Gradient varies more quickly on ends of the range than on
its middle.
Sinusoidal
The opposite of the curved type. Gradients varies more
quickly on center of the range than on its ends.
Spherical (increasing)
Gradient varies more quickly on the left of the range than
on its right.
Spherical (decreasing)
Gradient varies more quickly on the right than on the left.
Coloring Type for Segment/Selection
Figure 9.32.
The Coloring Type submenu
This option gives you additional control of the type of transition
from one endpoint to the other: as a line either in RGB space or
in HSV space.
Flip Segment/Selection
This option does a right-to-left flip of the selected range
(segment or selection), flipping all colors and endpoint
locations.
Replicate Segment/Selection
This option splits the selected range (segment or selection) into
two parts, each of which is a perfect compressed copy of the
original range.
Split Segments at Midpoints
This option splits each segment in the selected range in into
two segments, splitting at the location of the white
triangle.
Split Segments Uniformly
This option is similar to the previous one, but it
splits each segment halfway between the endpoints,
instead of at the white triangle.
Delete Selection
This option deletes all segments in the selected range, (segment
or selection) replacing them with a single black triangle at the
center, and enlarging the segments on both sides to fill
the void.
Re-center Segment's midpoint/Selection midpoints
This option moves the white triangle for each segment in the
selected range to a point halfway between the neighboring black
triangles.
Re-distribute Handles in Segment/Selection
This option causes the black and white triangles in the selected
range to be shifted so that the distances from one to the next are
all equal.
Blend Endpoints' Colors
This option is only available if more than one segment
is selected. It causes the colors at interior endpoints
in the range to be averaged, so that the transition
from each segment to the next is smooth.
Blend Endpoints' Opacity
This option does the same thing as the previous option,
but with opacity instead of color.
Caution
There is no "undo" available within the Gradient Editor, so be
careful!
Published under the terms of the GNU General Public License
![[Note]](../images/note.png)
![[Caution]](../images/caution.png)
