[css-color-5] more generalization on color interpolation

Author: svgeesus

css-color-5/Overview.bs

@@ -156,7 +156,7 @@ but different to the HSL Lightness.
 
 Only the [=color-adjuster=]s defined for a given [=colorspace=] are available.
 For example, it is not possible to use the HWB [=whiteness=] adjuster unless the colorspace is [=hwb=].
-The alpha adjuster is available on any color space.
+The alpha adjuster is available on any [=colorspace=].
 
 If the specified colorspace has a smaller gamut
 than the one in which the color to be adjusted is specified,
@@ -587,7 +587,7 @@ Adjusting colors: the ''color-adjust'' function {#coloradjust}
 Relative color syntax {#relative-colors}
 --------------------------------------------------------
 
-Besides specifying absolute coordinates, all color functions can also be used with a *relative syntax* to produce colors in the function's target color space, based on an existing color (henceforth referred to as "origin color"). This syntax consists of the keyword ''from'', a <<color>> value, and optionally numerical coordinates specific to the color function. To allow calculations on the original color's coordinates, there are single-letter keywords for each coordinate and `alpha` that corresponds to the color's alpha. If no coordinates are specified, the function merely converts the origin color to the target function's color space.
+Besides specifying absolute coordinates, all color functions can also be used with a *relative syntax* to produce colors in the function's target [=colorspace=], based on an existing color (henceforth referred to as "origin color"). This syntax consists of the keyword ''from'', a <<color>> value, and optionally numerical coordinates specific to the color function. To allow calculations on the original color's coordinates, there are single-letter keywords for each coordinate and `alpha` that corresponds to the color's alpha. If no coordinates are specified, the function merely converts the origin color to the target function's [=colorspace=].
 
 The following sections outline the relative color syntax for each color function.
 
@@ -747,7 +747,18 @@ When an origin color is present, the following keywords can also be used in this
 Interpolation {#interpolation}
 ===================================
 
-In general, interpolation between <<color>> values of the same color space occurs by linearly interpolating each component of the computed value of the color separately, in that colorspace.
+Color interpolation happens with
+gradients,
+compositing,
+filters,
+transitions,
+animations, and
+color mixing and color modification functions.
+
+In general, interpolation between <<color>> values of the same [=colorspace=]
+occurs by linearly interpolating each component of the computed value of the color
+separately, in that colorspace.
+This provides Web compatibility; legacy sRGB content interpolates in the sRGB space by default.
 
 Issue: Should gamut mapping occur before or after interpolation?