# Additive and Multiplicative Color Changes

Various scenes you create may require the gradual change in color of characters or scenery because of changes to the lighting of the scene. If the sun is setting on a beach, the colors of all of the scenery on the beach are going to darken or even redden before they absorb a dark purple or blue tint.

It would be quite time-consuming to figure out the colors of each object in your scene at each frame, and then recolor each drawing at each frame (which traditional painters did have to do). With Toon Boom Studio, you can automate colors changing over time by creating color changes in Color Transform elements and attaching all of the elements you want to transform to these effects elements.

There are two types of color transformations you can create: additive and multiplicative.

- With additive color transformations, you can add or subtract color values from selected color channels (red, green, blue and alpha).

You would select an additive color transformation if you wanted to add or remove a color from your drawings over time.

For example, if a fire suddenly starts in front of a character, the character would reflect more and more red or orange as the fire starts and grows larger.

- With multiplicative color transformations, you multiply the current values in the color channels (red, blue, green and alpha) by selected values to create new color values.

You would select a multiplicative color transformation if you wanted to create an effect that changes all color channels evenly.

For example, if you wanted to increase the redness of an image by 20%, you would multiply the red value by 1.2.

You can combine additive and multiplicative color transformations. Toon Boom Studio calculates the final value by first applying the multiplicative value and then the additive value. The formula looks like this:

    (Color * Multiplicative Values) + Additive Values = Final Color

You may notice that the values of your color go beyond the 256 colors that are actually displayed. Although you only see colors with values between 0 and 255, Toon Boom Studio saves the final value and uses it when you combine multiple Color Transforms.

See Also
Changing Color Over Time
Combining Multiple Color Transforms