The Blend tool renders a gradient based on the current foreground and background colors. The start and end points are set using the mouse. Simply drag and drop a line, and the gradient will be rendered using the foreground color as the start and the background color as the end. The quality of the resulting gradient will depend on the maximum number of colors available to the blend tool. ("Blend" and "Gradient" are often used interchangeably.)
The Blend Tool can be called in the following order, from the image-menu:
/ / .
The Tool can also be called by clicking the tool icon:
The L key will change the active tool to Gradient Fill.
Ctrl is used to create straight lines that are constrained to 15 degree absolute angles.
Options
The available tool options can be accessed
by double clicking the Gradient Tool icon.
The Opacity slider sets the transparency level for the gradient. A higher opacity setting results in a more opaque fill and a lower setting results in a more transparent fill.
The Mode dropdown list provides a selection of paint application modes. A list of these modes can be found in the glossary.
A variety of gradient patterns can be selected from the drop-down list. The tool causes a shading pattern that transitions from foreground to background color, in the direction the user determines by drawing a line in the image. For the purposes of drawing the gradient, the Reverse checkbox switches foreground and background.
The Offset Value is the "slope" of the gradient.
The Gimp provides 11 shapes, which can be selected from the drop-down list. Details on each of the shapes are given below.
The Lineargradient begins with the foreground color at the starting point of the drawn line and transitions linearly to the background color at the ending point.
The Bi-Linear shape proceeds in both directions from the starting point, for a distance determined by the lenth of the drawn line. It is useful, for example, for giving the appearance of a cylinder.
The Radial gradient gives a circle, with foreground color at the center and background color outside the circle. It gives the appearance of a sphere without directional lighting.
There are four shapes that are some variant on a square: Square, Shapeburst(angular), Shapeburst(spherical), and Shapeburst(dimpled). They all put the foreground color at the center of a square, whose center is at the start of the drawn line, and whose half-diagonal is the length of the drawn line. The four options provide a variety in the manner in which the gradient is calculated; experimentation is the best means of seeing the differences.
The Conical(symmetrical) shape gives the sensation of looking down at the tip of a cone, which appears to be illuminated with the background color from a direction determined by the direction of the drawn line.
Conical(asymmetric) is similar to Conical(symmetric) except that the "cone" appears to have a ridge where the line is drawn.
The Spiral tools provide spirals whose repeat width is determined by the length of the drawn line.
There are two repeat modes: Sawtooth Wave and Triangular Wave. The Sawtooth pattern is achieved by beginning with the foreground, transitioning to the background, then starting over with the foreground. The Triangular starts with the foreground, transitions to the background, then transitions back to the foreground.
Dithering is fully explained in the Glossary
Adaptive Supersampling is a more sophisticated means of smoothing the "jagged" effect of a sharp transiton of color along a slanted or curved line.