How to Use the Blend Tool in GIMP

The Blend tool (also called the Gradient tool) creates smooth transitions between two or more colors. It is used for backgrounds, sky effects, subtle shading, vignettes, and layer mask fades. Once you understand the basic drag-and-set workflow, it is one of the fastest ways to add depth to an image.

Creating a Basic Linear Gradient

1. Press L to activate the Blend tool.
2. Click where you want the gradient to start. Hold the mouse button.
3. Drag to where you want the gradient to end, then release.

In GIMP 2.10+, the gradient is interactive - You will see handles you can drag to adjust the start/end points, angle, and length. Press Enter or click elsewhere to commit the gradient.

Hold Ctrl while dragging to constrain the gradient to 15-degree angle increments (horizontal, vertical, 45-degree diagonal).

Setting Gradient Colors

By default, the gradient uses the current foreground and background colors. The start point of the drag becomes the foreground color, the end becomes the background color.

• Change the foreground color by clicking the foreground color swatch in the toolbox.
• Change the background color by clicking the background color swatch.
• In Tool Options, the gradient preview shows the current color combination. You can also select a preset gradient (like black-to-transparent) from the dropdown.

The "FG to BG (RGB)" option in the gradient picker uses your current foreground and background colors. The "FG to Transparent" option is very useful for layer masks and vignettes - it fades from your color to fully transparent.

Gradient Shapes (Linear, Radial, Conical)

In Tool Options, the Shape dropdown controls the gradient geometry:

Using Gradients on Layer Masks

The most powerful use of the Blend tool for photo editing: blending two photos together smoothly using a gradient on a layer mask.

1. Place two photos on separate layers.
2. Add a layer mask to the top photo layer (white mask - fully visible).
3. Click the mask thumbnail to target it.
4. Set foreground to black, background to white (press D).
5. Select the "FG to BG (RGB)" gradient preset and drag across the canvas.

The top layer now fades from fully visible (where mask is white) to fully transparent (where mask is black), blending seamlessly into the layer below. This is the same mask-based gradient technique described in the layer masks guide.

Custom Multi-Stop Gradients

To create gradients with more than two colors, use the Gradient Editor:

1. Go to Windows > Dockable Dialogs > Gradients to open the Gradients panel.
2. Click Edit Gradient (pencil icon) on any gradient to open the editor.
3. Double-click a color stop to change its color. Click between stops to add new ones. Drag stops to reposition them.
4. Save the gradient and it will appear in the picker for future use.