2.8. Выделение переднего плана

Рисунок 14.34. Инструмент «Выделение переднего плана» на панели инструментов

Инструмент Выделение переднего плана на панели инструментов

This tool lets you extract the foreground from the active layer or from a selection. With GIMP-2.10, selection refinement has been improved. After the selection is made, with its marching ants, you can copy-paste or click-and-drag it to another image used as background,and, inverting the selection, you can can make changes in background.

2.8.1. Активация инструмента

Инструмент можно активировать несколькими способами:

  • щелчком по значку инструмента на панели инструментов;

  • через меню изображения ИнструментыВыделениеВыделение переднего плана.

  • У этого инструмента по умолчанию нет клавиши быстрого доступа, но вы можете установить ее через диалог настройки програмы: ПравкаПараметрыИнтерфейсНастроить комбинации клавиш…ИнструментыВыделение переднего плана

2.8.2. Инструкция к применению

Let us start with an object distinctly different from background, not needing to be refined.

  1. Roughly select the foreground you want to extract. When you select this tool, the mouse pointer goes with the lasso icon. It actually works like the Free Select tool. Select as little as possible from the background.

    When the mouse pointer comes over line beginning, a small yellow circle appears: release mouse button to close selection. While selecting, click-and-drag draws a fuzzy line, drag only draws a straight line.

    If the mouse pointer doesn't cover start point, double clicking closes selection with a straight line.

    The selection is closed.

    As soon you click to start drawing, a small window pops up:

    For the moment, only a little cross is active, allowing to quit: returns to the original image.

  2. Press Enter to create the mask:

    The mouse pointer goes now with the Paint-brush icon. The dark blue area (this color can be changed) is for background. The light blue area covers the zone you have selected, on which you will paint to extract foreground. It contains the foreground area and a small part of background. Outside the selected area, the dark blue area is named Unknown pixels area.

    Options in the small window become active:

    • A Preview mask checkbox that toggles displaying a preview of the foreground extraction status.

    • A Select button that will be used to create the extraction after marking the foreground.

  3. Рисовать линию через передний план: используя кисть, размер которой можно изменить в параметрах, нарисуйте непрерывную линию в выделенном переднем плане, проходя через цвета для последущей выборки. Цвет линии не важен, но лучше не использовать цвет переднего плана. Не рисуйте на фоне.

    With this one-color object distinctly different from background, a few strokes are enough:

  4. Toggle preview to verify result.

    [Замечание] Замечание

    This Preview mask is a mask: you can draw directly on it and see result immediately.

  5. Try Matting Levin engine that may improve result.

  6. When you are satisfied with result, click on Select button to get the selection of the foreground with its marching ants.

2.8.3. Параметры

Рисунок 14.35. Параметры инструмента «Выделение переднего плана»

Параметры инструмента Выделение переднего плана

Обычно параметры инструмента отображаются в панели, присоединенной к панели инструментов, как только вы активируете его. Если их там нет, вы можете перейти к этой панели, выбрав в меню пункт ОкнаПанелиПараметры инструмента.

Mode; Feather edges
[Замечание] Замечание

Обратитесь к Инструментам выделения за справкой об параметрах, общих для всех инструментов выделения. Здесь описаны только параметры, присущие этому инструменту выделения.

Draw mode

Draw foreground: to draw what will be foreground.

Draw background: to draw what will be background.

Draw unknown: to add to your selection pixels that are in background.

Stroke width

The size of the brush.

Preview mask

You can adapt the color of the preview to your image.


Work with Matting global(default) and improve result with Matting Levin.


Default is 1. Repeating algorithm may improve result.

2.8.4. Refining Foreground Extraction

In most images, foreground is not distinctly different from background. Refining selection allows you now to extract these foregrounds. Procedure steps are the same as above, but, during drawing foreground, you will often toggle Preview, use Zoom (+ key), Draw background to delete unwanted background extraction areas. You can also work directly on Preview mask.

Рисунок 14.36. Example for Draw background

Example for Draw background

On the left: drawing foreground ill-advisedly went over background area: a part of background will be included in foreground selection!

In middle: Draw background option is checked: draw on inclusion and unwanted pixels.

On the right: unwanted selected pixels in background are no longer in foreground selection.

Рисунок 14.37. Example for Draw unknown

Example for Draw unknown

On the left: the selection left a small part of foreground unselected, in unknown pixels area.

On the right: with Draw unknown option checked, draw on unselected pixels. They are now selected.