7.40. アルファチャンネルしきい値...
| 7. 「レイヤー」メニュー |

### 7.40. アルファチャンネルしきい値...

The Threshold Alpha… command converts semi-transparent areas of the active layer into completely transparent or completely opaque areas, based on a threshold you set. It only works on layers which have an alpha channel. If the Lock alpha channel option is checked in the Layers Dialog, the filter will have no effect.

This command only works on a single layer.

#### 7.40.1. コマンドの呼び出し方

You can access this command

- From the main menu through Layer → Transparency → Threshold Alpha….

#### 7.40.2. 「アルファチャンネルを2階調化」ダイアログのご説明

図16.105 The 「Threshold Alpha」 filter options dialog

Presets, Input Type, Blending Options, Preview, Merge filter, Split view

  | 注記
  These options are described in 「Common Features」.

Value

  The threshold alpha value determines which values will become transparent or opaque. You can set the transparency value to be used by using the slider or by entering a value between 0 and 1 in the input box. All transparency values above this threshold will become opaque and all transparency values below or equal to this threshold will become completely transparent.

  | 注記
  このコマンドは完全透明な (アルファ値が 0 の) 画素を不透明化できません。

  図16.106 アルファチャンネル 2 階調化の例

  0-255 の透明度グラデーション
  しきい値を 50、 127、 210 に設定

7.39. Semi-Flatten |  | 7.41. 不透明部分を選択範囲に

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