diff --git a/README.md b/README.md
index 26cc522..e4abe3b 100644
--- a/README.md
+++ b/README.md
@@ -88,19 +88,31 @@ simple lookup by array index.
 | ---------- | ---------- |
 | `intensityToTurbo` | `(value: number) => Color` |
 
+Parameters:
+
+* `value`: An integer in the range 0-255.
+
+
 ### :gear: snapColorToTurbo
 
 Accepts an arbitrary RGB triplet and returns the nearest color (by Euclidian
 distance) in the Turbo colormap. There is no interpolation; one of the 256
 colors in the exact Turbo palette is always returned.
 
-For performance, this uses a pre-initialized k-d tree to perform
-nearest-neighbor search.
+For performance, this uses a pre-initialized k-d tree to perform nearest-neighbor
+search.
 
 | Function | Type |
 | ---------- | ---------- |
 | `snapColorToTurbo` | `(rgbColor: Color, cache?: Map<string, number> or undefined) => Uint8ClampedArray` |
 
+Parameters:
+
+* `rgbColor`: An array-like RGB triplet.
+* `cache`: A Map to use as a lookup cache, to avoid repeated nearest-neighbor
+searches.
+
+
 ### :gear: snapColorToIntensity
 
 Accepts an arbitrary RGB triplet and returns the index (0-255) of the nearest
@@ -115,8 +127,7 @@ Parameters:
 
 * `rgbColor`: An array-like RGB triplet.
 * `cache`: A Map to use as a lookup cache, to avoid repeated nearest-neighbor
-searches. If not provided, a temporary one will be used for each function
-call.
+searches.
 
 
 ### :gear: snapNormalizedToTurbo
diff --git a/src/index.ts b/src/index.ts
index a308981..76ece33 100644
--- a/src/index.ts
+++ b/src/index.ts
@@ -135,6 +135,10 @@ const rgbTree = new KDTree(rgbColormap, 3);
 /**
  * Convert an integer in the range 0-255 to a Turbo RGB triplet. This is a
  * simple lookup by array index.
+ *
+ * @param value An integer in the range 0-255.
+ *
+ * @returns A Uint8ClampedArray Turbo RGB triplet.
  */
 export function intensityToTurbo(value: number): Color {
   return rgbColormap[value];
@@ -145,8 +149,14 @@ export function intensityToTurbo(value: number): Color {
  * distance) in the Turbo colormap. There is no interpolation; one of the 256
  * colors in the exact Turbo palette is always returned.
  *
- * For performance, this uses a pre-initialized k-d tree to perform
- * nearest-neighbor search.
+ * For performance, this uses a pre-initialized k-d tree to perform nearest-neighbor
+ * search.
+ *
+ * @param rgbColor An array-like RGB triplet.
+ * @param cache A Map to use as a lookup cache, to avoid repeated nearest-neighbor
+ *   searches.
+ *
+ * @returns A Turbo RGB triplet in a Uint8ClampedArray.
  */
 export function snapColorToTurbo(rgbColor: Color, cache?: Map<string, number>) {
   const index = snapColorToIntensity(rgbColor, cache);
@@ -160,8 +170,9 @@ export function snapColorToTurbo(rgbColor: Color, cache?: Map<string, number>) {
  *
  * @param rgbColor An array-like RGB triplet.
  * @param cache A Map to use as a lookup cache, to avoid repeated nearest-neighbor
- *   searches. If not provided, a temporary one will be used for each function
- *   call.
+ *   searches.
+ *
+ * @returns An integer in the range 0-255.
  */
 export function snapColorToIntensity(
   rgbColor: Color,
@@ -199,6 +210,8 @@ export function snapNormalizedToTurbo(value: number): Color {
  * Turbo, a new in-between color is generated via simple Euclidian interpolation.
  *
  * @param value A number in the range 0-1.
+ *
+ * @returns A Turbo RGB triplet in a standard JavaScript Array.
  */
 export function interpolateNormalizedToTurbo(value: number): Color {
   const a = Math.floor(value * 255);
@@ -223,6 +236,8 @@ export function interpolateNormalizedToTurbo(value: number): Color {
  * averaged.
  *
  * @param gray An array-like RGB triplet.
+ *
+ * @returns A Turbo RGB triplet in a Uint8ClampedArray.
  */
 export function grayscaleToTurbo(gray: Color) {
   const r = gray[0];