Figure 13.46. Toolbox Fill
This tool fills a selection with the current foreground color. If you
Ctrl+click and use the Bucket tool, it will use the background color
instead. Depending on how the tool options are set, the Bucket Fill tool
will either fill the entire selection, or only parts whose colors are
similar to the point you click on. The tool options also affect the way
transparency is handled.
The amount of fill depends on what Fill Threshold you have specified. The
fill threshold determines how far the fill will spread (similar to the way
in which the magic wand works). The fill starts at the point where you
click and spreads outward until the color or alpha value becomes
When you fill objects in a transparent layer (such as letters in a text
layer) with a different color than before, you may find that a border of
the old color still surrounds the objects. This is due to a low
fill-threshold in the Bucket Fill options dialog. With a low threshold,
the bucket tool won't fill semi-transparent pixels, and they will stand
out against the fill because they have kept their original color.
If you want to fill areas that are totally transparent, you have to make
sure that the “Lock” option (in the Layers dialog) is
unchecked. If this option is checked, only the non-transparent parts of
the layer will be filled.
3.3.1. Activating the tool
You can find the Bucket Fill tool from the image-menu through:
You can also call it by clicking the tool icon:
in the toolbox.
or by pressing the
3.3.2. Key modifiers (Defaults)
Figure 13.47. “Bucket Fill” tool options
Normally, tool options are displayed in a window attached under the
Toolbox as soon as you activate a tool. If they are not, you can access
them from the image menu bar through
→ → which opens the option window of the selected tool.
See Paint Tools
for help with options that are common to all these tools. Only
options that are specific to the Bucket Fill tool are
GIMP provides three fill types:
FG Color Fill
sets the fill color to the currently selected foreground
BG Color Fill
sets the fill color to the currently selected background
sets the fill color to the currently selected pattern. You
can select the pattern to use in a drop down list.
This drop-down list allows the user to select one of many
fill patterns to use on the next fill operation. The manner
in which the list is presented is controlled by the four
buttons at the bottom of the selector.
Fill whole selection
This option makes GIMP fill a pre-existent selection or the
whole image. A quicker approach to do the same thing could
be to click and drag the foreground, background or pattern
color, leaving it onto the selection.
Fill similar colors
This is the default setting: the tool fills the area with a
color near the pixel onto you have clicked. The color
similarity is defined by a brightness threshold, that you
can set by a value or by a cursor position.
Finding Similar Colors
Under this section you can find two options:
Fill Transparent Areas
The option Fill Transparent Areas
offers the possibility of filling areas with low opacity.
The option Sample Merged
toggles the sampling from all layers. If Sample Merged is
active, fills can be made on a lower layer, while the color
information used for threshold checking is located further
up. Simply select the lower level and ensure that a layer
above is visible for color weighting.
The Threshold slider sets the level at which color weights
are measured for fill boundaries. A higher setting will fill
more of a multi colored image and conversely, a lower
setting will fill less area.
With this option you can choose which component of the image
GIMP shall use to calculate the similarity and to determine
the borders of filling.
The components you can choose from are
This option is not easy to understand. You have chosen,
for example, the Red channel. When you click on any pixel,
the tool searches for contiguous pixels similar for
the red channel to the clicked pixel,
according to the set threshold. Here is an example:
Original image: three strips with gradients of pure
colors. Red (255;0;0), Green (0;255;0), Blue
(0;0;255). We are going to use the Bucket-fill tool
with the magenta color and a Threshold set to 15.
Image 1: Fill By = Composite. We successively clicked in the
three color strips. Every strip is filled according
to the threshold.
Image 2: Fill By = Red. We clicked in the red strip. The
tool searches for contiguous pixels which have a similar
value in the red channel, according to the set
threshold. Only a narrow area corresponds to these
standards. In the green and the blue strip, the value
of pixels in the red channel is 0, very much different from
the red channel value of the clicked pixel: the color
doesn't spread to them.
Image 3: Fill By = Red. We clicked in the green strip.
There, the value of the clicked pixel in the red channel is
0. All pixels in the green and the blue strips have the
same red channel value (0): they are all painted.
Example for “Fill By”
3.3.4. Fill a feathered selection
By clicking repeatedly in a selection with feathered edges, you
progressively fill the feathered border:
Figure 13.49. Example for “Fill a feathered Selection”