Difference Clouds command changes colors partially in cloud-like areas: The filter renders Solid Noise cloud in an automatically created new layer, and sets the layer mode to Difference, then merges this layer over the specified image.

画像がインデックス化カラーの場合はメニュー項目が灰色無効となって使用できません。

This filter is found in the image window menu under Filters → Render → Noise → Difference Clouds….

This script has no options.