Changing image appearance

Switching LUTs

You can change the colors of the LUT by selecting an alternative option from the Image –> Lookup tables submenu.

Use the Control Panel to frequently access the same menu: If you want to explore LUTs quickly, use Plugins –> Utilities –> Control Panel. This opens a window that allows you to double-click on commands from any menu or submenu to apply that command quickly.

Adjusting Brightness & Contrast

The main command to change the brightness of an image is Image –> Adjust –> Brightness/Contrast... Since you’re likely to use it a lot, it is worth learning the shortcut: Shift + C.

The Brightness/Contrast dialog has four sliders: Minimum, Maximum, Brightness & Contrast. They are linked together: changing either of the first two also results in a change to the last two, and vice versa.

Supposing you have a grayscale LUT, with colors ranging from black to white, you should see that

• All pixels with a value less than or equal to the Minimum will be shown as black

• All pixels with a value greater than or equal to the Maximum will be shown as white

• All other pixels with a value in between will be shown using a shade of gray

Use the minimum & maximum sliders: Despite the name of the command implying Brightness and Contrast are the star performers, I would argue that the Minimum and Maximum sliders are far more intuitive.

I use Minimum and Maximum almost exclusively.

Exercise 11.2

• Does adjusting any of the sliders in the brightness & contrast dialog change the pixel values or only the LUT?

• What happens if you press Apply?