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 or introduces others colors, in the direction the user determines by drawing a line in the image. For the purposes of drawing the gradient, clicking on the Reverse reverses the gradient direction with the effect, for instance, of swapping the foreground and background colors.

On the right hand, a button to open the Gradient Editor dialog.

GIMP には 11 種類の形状があり、 引き出しリストから選べるようになっています。 それぞれの形状を詳しく解説します。

図14.68 グラデーションの形状の例

線形

双線型

放射状

ディザー効果の十分な説明が 用語集 で読めます。

これは斜線や曲線上での際だった色変化で起こるぎざぎざの現象を抑え、 より高度な方法で平滑化します。 ともかく試してみないことには選びようがないオプションですね。

オフセット 値はグラデーションの「傾斜」の増加を可能にします。 クリックした始点と色変化が起こる位置を分けてその間の距離を定めます。 線形以外の形状にはこのオプションが適用されません。

図14.72 「ブレンド」ツール: オフセットの例

上段のオフセット = 0、 下段のオフセット = 50%

	警告
	The option must be activated (with Shift also) before starting drawing gradient.

When this option is checked, gradient tool works as in GIMP 2.8: the gradient line disappears as soon as you release the mouse button. You can't edit color stops before applying the gradient fill.

When this option is checked, gradient tool works as in GIMP 2.8: the custom gradient is not created automatically and must be created manually. The option can be activated before starting drawing gradient or if the active gradient is not the custom gradient. Allows changing user-writable gradients directly rather than creating copies of them.

All the Gradient Editor dialog features are available directly on canvas. You can create and delete color stops, select and shift them, assign colors to color stops, change blending and coloring for segments between color stops, create color stops from midpoints.

Select a gradient in the gradient dialog. Click and drag on canvas. A line is drawn and the gradient is displayed. You can edit this gradient by moving the mouse pointer on this line. As soon as you try to edit gradient, GIMP creates a custom gradient, which is a copy of the selected gradient. It becomes the active gradient and will be preserved across sessions. Here, we use the Abstract3 gradient.

The Abstract3 gradient, with endpoints

At both ends of the line, you can see a Start endpoint and an End endpoint. Click and drag an endpoint (the mouse pointer is accompanied with a moving cross) to move it where you want on your screen. A small window appears showing data about the selected endpoint : the position of the mouse (coordinate origin is the upper left corner of image or selection), the starting (left) and the ending (right) color of the gradient.

End point moved

	注記
	In you only move endpoints, the custom gradient is not created yet.

On the line, you can see several small squares. These are Stops that divide gradient into segments. You can edit segments separately. Click and drag stops to move them (the active endpoint takes a yellow color). As soon as you move a stop, the custom gradient is created. The small data window shows a button that allow you to remove the active stop.

Stop point moved and data window

If you move the mouse pointer on the line, a Midpoint shows up. Then, the small data window has two buttons : to create a new stop at midpoint, and to center midpoint.

For Stops and Midpoints, Position refers to the gradient line: 0 is start endpoint, 100 is end endpoint.

Blending: you can change the blending mode between two stops, using the drop-down list. The Step option creates a hard-edge transition between the two adjacent color stops at the midpoint.

図14.73 「Step」 option example

Original gradient

Step applied at Midpoint2

Changing color: in stop and end data windows, you have color buttons with a drop-down list. The default option is Fixed; this means that color choice will be independent from foreground and background colors. Click on a color button to open a color selector.

Ctrl キーは制限つきの直線を引くのに使われます。 線の傾きは 15 度刻みの方向のいずれかのみ選べます。

Alt or Ctrl+Alt to move the whole line.

The Gradient Editor still exists: 「グラデーションエディター」.