GIMP brush format is native to the GIMP image editor for storing a brush or a texture. It can be used in all Paint Tools, for example Pencil and Paintbrush. It works by repeating the brush bitmap as you move the tool. The Spacing parameter sets the distance between the brush marks as a percentage of brush width. Its default value can be set in the brush file.
You can also use GIMP to create new brushes in this format. Custom brushes can be loaded into GIMP for use in the paint tools by copying them into one of the Brush Folders - select Edit > Preferences in the menu bar, expand the Folders section and choose Brushes to see the recognized Brush Folders or to add new ones.
This page hosts a formal specification of GIMP brush file version 2 using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
digraph {
rankdir=LR;
node [shape=plaintext];
subgraph cluster__gimp_brush {
label="GimpBrush";
graph[style=dotted];
gimp_brush__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="len_header_pos">0</TD><TD PORT="len_header_size">4</TD><TD>u4be</TD><TD PORT="len_header_type">len_header</TD></TR>
<TR><TD PORT="header_pos">4</TD><TD PORT="header_size">(len_header - 4)</TD><TD>Header</TD><TD PORT="header_type">header</TD></TR>
</TABLE>>];
gimp_brush__inst__len_body [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">id</TD><TD BGCOLOR="#E0FFE0">value</TD></TR>
<TR><TD>len_body</TD><TD>((header.width * header.height) * I__COLOR_DEPTH[header.bytes_per_pixel])</TD></TR>
</TABLE>>];
gimp_brush__inst__body [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="body_pos">len_header</TD><TD PORT="body_size">len_body</TD><TD></TD><TD PORT="body_type">body</TD></TR>
</TABLE>>];
subgraph cluster__header {
label="GimpBrush::Header";
graph[style=dotted];
header__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="version_pos">0</TD><TD PORT="version_size">4</TD><TD>u4be</TD><TD PORT="version_type">version</TD></TR>
<TR><TD PORT="width_pos">4</TD><TD PORT="width_size">4</TD><TD>u4be</TD><TD PORT="width_type">width</TD></TR>
<TR><TD PORT="height_pos">8</TD><TD PORT="height_size">4</TD><TD>u4be</TD><TD PORT="height_type">height</TD></TR>
<TR><TD PORT="bytes_per_pixel_pos">12</TD><TD PORT="bytes_per_pixel_size">4</TD><TD>u4be→ColorDepth</TD><TD PORT="bytes_per_pixel_type">bytes_per_pixel</TD></TR>
<TR><TD PORT="magic_pos">16</TD><TD PORT="magic_size">4</TD><TD></TD><TD PORT="magic_type">magic</TD></TR>
<TR><TD PORT="spacing_pos">20</TD><TD PORT="spacing_size">4</TD><TD>u4be</TD><TD PORT="spacing_type">spacing</TD></TR>
<TR><TD PORT="brush_name_pos">24</TD><TD PORT="brush_name_size">⇲</TD><TD>str(UTF-8)</TD><TD PORT="brush_name_type">brush_name</TD></TR>
</TABLE>>];
}
subgraph cluster__bitmap {
label="GimpBrush::Bitmap";
graph[style=dotted];
bitmap__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="rows_pos">0</TD><TD PORT="rows_size">...</TD><TD>Row</TD><TD PORT="rows_type">rows</TD></TR>
<TR><TD COLSPAN="4" PORT="rows__repeat">repeat _root.header.height times</TD></TR>
</TABLE>>];
}
subgraph cluster__row {
label="GimpBrush::Row";
graph[style=dotted];
row__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="pixels_pos">0</TD><TD PORT="pixels_size">...</TD><TD>switch (_root.header.bytes_per_pixel)</TD><TD PORT="pixels_type">pixels</TD></TR>
<TR><TD COLSPAN="4" PORT="pixels__repeat">repeat _root.header.width times</TD></TR>
</TABLE>>];
row__seq_pixels_switch [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#F0F2E4">case</TD><TD BGCOLOR="#F0F2E4">type</TD></TR>
<TR><TD>:color_depth_grayscale</TD><TD PORT="case0">PixelGray</TD></TR>
<TR><TD>:color_depth_rgba</TD><TD PORT="case1">PixelRgba</TD></TR>
</TABLE>>];
subgraph cluster__pixel_gray {
label="GimpBrush::Row::PixelGray";
graph[style=dotted];
pixel_gray__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="gray_pos">0</TD><TD PORT="gray_size">1</TD><TD>u1</TD><TD PORT="gray_type">gray</TD></TR>
</TABLE>>];
pixel_gray__inst__red [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">id</TD><TD BGCOLOR="#E0FFE0">value</TD></TR>
<TR><TD>red</TD><TD>0</TD></TR>
</TABLE>>];
pixel_gray__inst__green [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">id</TD><TD BGCOLOR="#E0FFE0">value</TD></TR>
<TR><TD>green</TD><TD>0</TD></TR>
</TABLE>>];
pixel_gray__inst__blue [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">id</TD><TD BGCOLOR="#E0FFE0">value</TD></TR>
<TR><TD>blue</TD><TD>0</TD></TR>
</TABLE>>];
pixel_gray__inst__alpha [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">id</TD><TD BGCOLOR="#E0FFE0">value</TD></TR>
<TR><TD>alpha</TD><TD>gray</TD></TR>
</TABLE>>];
}
subgraph cluster__pixel_rgba {
label="GimpBrush::Row::PixelRgba";
graph[style=dotted];
pixel_rgba__seq [label=<<TABLE BORDER="0" CELLBORDER="1" CELLSPACING="0">
<TR><TD BGCOLOR="#E0FFE0">pos</TD><TD BGCOLOR="#E0FFE0">size</TD><TD BGCOLOR="#E0FFE0">type</TD><TD BGCOLOR="#E0FFE0">id</TD></TR>
<TR><TD PORT="red_pos">0</TD><TD PORT="red_size">1</TD><TD>u1</TD><TD PORT="red_type">red</TD></TR>
<TR><TD PORT="green_pos">1</TD><TD PORT="green_size">1</TD><TD>u1</TD><TD PORT="green_type">green</TD></TR>
<TR><TD PORT="blue_pos">2</TD><TD PORT="blue_size">1</TD><TD>u1</TD><TD PORT="blue_type">blue</TD></TR>
<TR><TD PORT="alpha_pos">3</TD><TD PORT="alpha_size">1</TD><TD>u1</TD><TD PORT="alpha_type">alpha</TD></TR>
</TABLE>>];
}
}
}
gimp_brush__seq:len_header_type -> gimp_brush__seq:header_size [color="#404040"];
gimp_brush__seq:len_header_type -> gimp_brush__seq:header_size [color="#404040"];
gimp_brush__seq:header_type -> header__seq [style=bold];
header__seq:width_type -> gimp_brush__inst__len_body [color="#404040"];
header__seq:height_type -> gimp_brush__inst__len_body [color="#404040"];
header__seq:bytes_per_pixel_type -> gimp_brush__inst__len_body [color="#404040"];
gimp_brush__seq:len_header_type -> gimp_brush__inst__body:body_pos [color="#404040"];
gimp_brush__inst__len_body:len_body_type -> gimp_brush__inst__body:body_size [color="#404040"];
bitmap__seq:rows_type -> row__seq [style=bold];
header__seq:height_type -> bitmap__seq:rows__repeat [color="#404040"];
row__seq:pixels_type -> row__seq_pixels_switch [style=bold];
row__seq_pixels_switch:case0 -> pixel_gray__seq [style=bold];
row__seq_pixels_switch:case1 -> pixel_rgba__seq [style=bold];
header__seq:bytes_per_pixel_type -> row__seq:pixels_type [color="#404040"];
header__seq:width_type -> row__seq:pixels__repeat [color="#404040"];
pixel_gray__seq:gray_type -> pixel_gray__inst__alpha [color="#404040"];
}