The Color panel is used to choose color for various tools and selected objects.
About the Color panel
The Color panel can operate in several color modes—HSL, RGB, RGB Hex, CMYK and LAB—and has various ways of defining color—color wheel (HSL only), color boxes and color sliders. Color tints can also be applied from within the panel.
Color panel (HSL color wheel): (A) Primary/Secondary (left) or Stroke/Fill color selectors with color 'none' swatch and 'swap' arrow, (B) HSL values, (C) Switch to opacity/noise, (D) Panel Preferences (E) Color picker and picked color swatch, (F) Saturation/Lightness control, (G) Hue control, (H) Opacity controls, (J) Noise controls.
Like the Swatches panel, the Color panel takes on different appearances depending on the active Persona and on the selected tool. The large color selectors indicate the currently selected colors.
In Publisher and Designer Personas, objects have fill and stroke color properties. The stroke color is represented by the cutout (donut) color selector. The fill is represented by the solid color selector.
In Photo Persona, the two solid color selectors indicate interchangeable Primary and Secondary colors.
The active color selector is shown at the front of the two color selectors. Choosing a new color will apply it to the active color selector.
Using the Color panel
With the Color panel, colors can be applied to an object or for use by a tool in just a few clicks. Opacity and noise are further color attributes which can be applied.
To set the color of a selector:
Click the selector you want to apply the color to. It will show at the front of the two color selectors.
Do one of the following:
Choose a color from the color model's Wheel (HSL only), Sliders, or Boxes.
Click the picked color swatch.
Click the None swatch to make the color completely transparent (for the tool, fill or stroke).
To switch colors between the selectors:
Click the double-headed arrow. The colors switch (but the active swatch selector remains the same.)
To adjust opacity or noise setting:
Select the toggle button to the bottom-left of the panel.
Drag the slider to set the value.
Color selection preferences and color models
When choosing colors in the Color panel, you can choose from various selection preferences and color model values. The color selection preferences are changed in the Panel Preferences menu.
Depending on the color model selected, you can also choose to work in 8 bit, 16 bit or Percentage mode.
Some of the selection methods allow you to set color using values other than RGB. This doesn't change the working color profile of the document, but changes the input values for the colors.
The following color selection preferences are available from the Panel Preferences menu.
Wheel—HSL Color Wheel
Drag on the outer ring to set the hue.
Drag in the triangle to set saturation and lightness.
Sliders—RGB, RGB Hex, HSL, CMYK, LAB, Grayscale
Select the color mode from the pop-up menu.
(Optional) From the Panel Preferences menu, select 8 bit, 16 bit or Percentage.
Drag sliders or type directly into the value boxes to set the color values.
Boxes—Hue, Saturation, Lightness only
Hue—Drag on the hue slider to set the hue, drag in the box to set the saturation and lightness.
Saturation—Drag on the saturation slider to set the saturation, drag in the box to set the hue and lightness.
Lightness—Drag on the lightness slider to set the lightness, drag in the box to set the saturation and hue.
Tint
Drag the slider to control the color tint. The further to the left the slider is positioned, the less ink is applied to the page.
By default, the color space is locked when using Sliders (e.g., CMYK sliders) to prevent it from changing. This avoids inadvertently swapping to another mode after using swatches or selecting a different object created with a different color mode. When unlocked, the Color panel will remember the color mode that the selected object was created in.
Using the Color Picker
The picker lets you sample colors within or outside Affinity Publisher, then use them in your design.
To use the Color Picker:
Drag the Color Picker icon to the color you want to sample.
Click the selector you want to apply the color to.
Click the swatch next to the Color Picker to apply the color.
Saving chosen colors for later use
Once your color has been chosen and applied to a tool or object, there are several ways to preserve this color for later use.
The following options are available from the Panel Preferences menu.
Copy Color to Clipboard as Hex—this calculates the current color's Hex value and adds it to the clipboard. This is useful for web developers, to standardize on colors between graphics and HTML coding in a web environment.
Add Color to Swatch—adds the current color to the currently loaded palette in the Swatches panel.
Add Chord to Swatch pop-up menu—adds a chord of the current color to the currently loaded palette in the Swatches panel.
When choosing colors in the Color panel, you can choose from various selection preferences and color model values. The color selection preferences are changed in the Panel Preferences menu.
By default, the color space is locked when using 
To use the Color Picker: