Defining Custom Colors
From LibreOffice Help
If you want, you can mix a custom color and add it to a color table.
To define a custom color
- Choose Format - Area and click the Colors tab. A table of the predefined colors is displayed.
Changes made to the standard color table are permanent and are saved automatically.
- Click a color in the table that is similar to the one you want to mix. The color appears in the upper preview box to the right of the table.
- Select the RGB or CMYK color model in the box below the preview boxes.
LibreOffice uses only the RGB color model for printing in color. The CMYK controls are provided only to ease the input of color values using CMYK notation.
The RGB color model mixes red, green and blue light to create colors on a computer screen. In the RGB model, the three color components are additive and can have values ranging from 0 (black) to 255 (white). The CMYK color model combines Cyan (C), Magenta (M), Yellow (Y), and blacK (K, also used for "Key") to create colors for printing. The four colors of the CMYK models are subtractive and are defined as percentages. Black corresponds to 100 % and white to 0 %.
- Enter a numeric value in the boxes next to the color components. The new color appears in the preview box directly above the color model box.
You can also create a color using a color spectrum. Click the Edit button to open the Color dialog. Click a color. Use the Hue, Saturation, and Brightness boxes to adjust your color selection.
- Do one of the following:
- If you want to replace the color in the standard color table that your custom color is based on, click Modify.
- If you want to add your custom color to the standard color table, enter a name in the Name text box and click Add.