8.8. Баланс белого

The White Balance command automatically adjusts the colors of the active layer by stretching the Red, Green and Blue channels separately. To do this, it discards pixel colors at each end of the Red, Green and Blue histograms which are used by only 0.05% of the pixels in the image and stretches the remaining range as much as possible. The result is that pixel colors which occur very infrequently at the outer edges of the histograms (perhaps bits of dust, etc.) do not negatively influence the minimum and maximum values used for stretching the histograms, in comparison with Stretch Contrast. Like «Stretch Contrast», however, there may be hue shifts in the resulting image.

This command suits images with poor white or black. Since it tends to create pure white (and black), it may be useful e.g. to enhance photographs.

White Balance operates on layers from RGB images. If the image is Indexed or Grayscale, the menu item is insensitive and grayed out.

8.8.1. Activate the Command

  • You can access this command from the image menubar through ColorsAutoWhite Balance.

8.8.2. «White Balance» example

Рисунок 15.133. Исходное изображение

Исходное изображение

Активный слой и его гистограммы красного, зелёного и синего до применения команды «Баланс белого».

Рисунок 15.134. Изображение после применения команды

Изображение после применения команды

The active layer and its Red, Green and Blue histograms after «White Balance». Poor white areas in the image became pure white.

Растяжение гистограммы создаёт пустоты между колоннами точек, придавая ей полосатый вид.