diff --git a/contrib/img_hash.go b/contrib/img_hash.go
index f3e44429..858a0122 100644
--- a/contrib/img_hash.go
+++ b/contrib/img_hash.go
@@ -8,31 +8,58 @@ import (
 	"gocv.io/x/gocv"
 )
 
+// ImgHashBase defines the interface used for all of the img_hash algorithms.
 type ImgHashBase interface {
 	Compare(a, b gocv.Mat) float64
 	Compute(inputArr gocv.Mat, outputArr *gocv.Mat)
 }
 
+// PHash is implementation of the PHash algorithm.
+//
 type PHash struct{}
 
+// Compute computes hash of the input image using PHash.
+//
+// For further information, see:
+// https://docs.opencv.org/master/de/d29/classcv_1_1img__hash_1_1ImgHashBase.html#ae2d9288db370089dfd8aab85d5e0b0f3
+//
 func (hash PHash) Compute(input gocv.Mat, output *gocv.Mat) {
 	C.pHashCompute(C.Mat(input.Ptr()), C.Mat(output.Ptr()))
 }
 
+// Compare compares the hash value between a and b using PHash.
+//
+// For further information, see:
+// https://docs.opencv.org/master/de/d29/classcv_1_1img__hash_1_1ImgHashBase.html#a444a3e9ec792cf029385809393f84ad5
+//
 func (hash PHash) Compare(a, b gocv.Mat) float64 {
 	return float64(C.pHashCompare(C.Mat(a.Ptr()), C.Mat(b.Ptr())))
 }
 
+// AverageHash is implementation of the AverageHash algorithm.
+//
 type AverageHash struct{}
 
+// Compute computes hash of the input image using AverageHash.
+//
+// For further information, see:
+// https://docs.opencv.org/master/de/d29/classcv_1_1img__hash_1_1ImgHashBase.html#ae2d9288db370089dfd8aab85d5e0b0f3
+//
 func (hash AverageHash) Compute(input gocv.Mat, output *gocv.Mat) {
 	C.averageHashCompute(C.Mat(input.Ptr()), C.Mat(output.Ptr()))
 }
 
+// Compare compares the hash value between a and b using AverageHash.
+//
+// For further information, see:
+// https://docs.opencv.org/master/de/d29/classcv_1_1img__hash_1_1ImgHashBase.html#a444a3e9ec792cf029385809393f84ad5
+//
 func (hash AverageHash) Compare(a, b gocv.Mat) float64 {
 	return float64(C.averageHashCompare(C.Mat(a.Ptr()), C.Mat(b.Ptr())))
 }
 
+// BlockMeanHash is implementation of the BlockMeanHash algorithm.
+//
 type BlockMeanHash struct {
 	Mode BlockMeanHashMode
 }
@@ -45,10 +72,20 @@ const (
 	BlockMeanHashModeDefault = BlockMeanHashMode0
 )
 
+// Compute computes hash of the input image using BlockMeanHash.
+//
+// For further information, see:
+// https://docs.opencv.org/master/de/d29/classcv_1_1img__hash_1_1ImgHashBase.html#ae2d9288db370089dfd8aab85d5e0b0f3
+//
 func (hash BlockMeanHash) Compute(input gocv.Mat, output *gocv.Mat) {
 	C.blockMeanHashCompute(C.Mat(input.Ptr()), C.Mat(output.Ptr()), C.int(hash.Mode))
 }
 
+// Compare compares the hash value between a and b using BlockMeanHash.
+//
+// For further information, see:
+// https://docs.opencv.org/master/de/d29/classcv_1_1img__hash_1_1ImgHashBase.html#a444a3e9ec792cf029385809393f84ad5
+//
 func (hash BlockMeanHash) Compare(a, b gocv.Mat) float64 {
 	return float64(C.blockMeanHashCompare(C.Mat(a.Ptr()), C.Mat(b.Ptr()), C.int(hash.Mode)))
 }
@@ -56,16 +93,30 @@ func (hash BlockMeanHash) Compare(a, b gocv.Mat) float64 {
 // TODO: BlockMeanHash.GetMean isn't implemented, because it requires state from the last
 // call to Compute, and there's no easy way to keep it.
 
+// ColorMomentHash is implementation of the ColorMomentHash algorithm.
+//
 type ColorMomentHash struct{}
 
+// Compute computes hash of the input image using ColorMomentHash.
+//
+// For further information, see:
+// https://docs.opencv.org/master/de/d29/classcv_1_1img__hash_1_1ImgHashBase.html#ae2d9288db370089dfd8aab85d5e0b0f3
+//
 func (hash ColorMomentHash) Compute(input gocv.Mat, output *gocv.Mat) {
 	C.colorMomentHashCompute(C.Mat(input.Ptr()), C.Mat(output.Ptr()))
 }
 
+// Compare compares the hash value between a and b using ColorMomentHash.
+//
+// For further information, see:
+// https://docs.opencv.org/master/de/d29/classcv_1_1img__hash_1_1ImgHashBase.html#a444a3e9ec792cf029385809393f84ad5
+//
 func (hash ColorMomentHash) Compare(a, b gocv.Mat) float64 {
 	return float64(C.colorMomentHashCompare(C.Mat(a.Ptr()), C.Mat(b.Ptr())))
 }
 
+// MarrHildrethHash is implementation of the MarrHildrethHash algorithm.
+//
 type MarrHildrethHash struct {
 	Alpha float32
 	Scale float32
@@ -75,16 +126,28 @@ func NewMarrHildrethHash() MarrHildrethHash {
 	return MarrHildrethHash{2.0, 1.0}
 }
 
+// Compute computes hash of the input image using MarrHildrethHash.
+//
+// For further information, see:
+// https://docs.opencv.org/master/de/d29/classcv_1_1img__hash_1_1ImgHashBase.html#ae2d9288db370089dfd8aab85d5e0b0f3
+//
 func (hash MarrHildrethHash) Compute(input gocv.Mat, output *gocv.Mat) {
 	C.marrHildrethHashCompute(C.Mat(input.Ptr()), C.Mat(output.Ptr()),
 		C.float(hash.Alpha), C.float(hash.Scale))
 }
 
+// Compare compares the hash value between a and b using MarrHildrethHash.
+//
+// For further information, see:
+// https://docs.opencv.org/master/de/d29/classcv_1_1img__hash_1_1ImgHashBase.html#a444a3e9ec792cf029385809393f84ad5
+//
 func (hash MarrHildrethHash) Compare(a, b gocv.Mat) float64 {
 	return float64(C.marrHildrethHashCompare(C.Mat(a.Ptr()), C.Mat(b.Ptr()),
 		C.float(hash.Alpha), C.float(hash.Scale)))
 }
 
+// RadialVarianceHash is implementation of the RadialVarianceHash algorithm.
+//
 type RadialVarianceHash struct {
 	Sigma          float64
 	NumOfAngleLine int
@@ -94,11 +157,21 @@ func NewRadialVarianceHash() RadialVarianceHash {
 	return RadialVarianceHash{1, 180}
 }
 
+// Compute computes hash of the input image using RadialVarianceHash.
+//
+// For further information, see:
+// https://docs.opencv.org/master/de/d29/classcv_1_1img__hash_1_1ImgHashBase.html#ae2d9288db370089dfd8aab85d5e0b0f3
+//
 func (hash RadialVarianceHash) Compute(input gocv.Mat, output *gocv.Mat) {
 	C.radialVarianceHashCompute(C.Mat(input.Ptr()), C.Mat(output.Ptr()),
 		C.double(hash.Sigma), C.int(hash.NumOfAngleLine))
 }
 
+// Compare compares the hash value between a and b using RadialVarianceHash.
+//
+// For further information, see:
+// https://docs.opencv.org/master/de/d29/classcv_1_1img__hash_1_1ImgHashBase.html#a444a3e9ec792cf029385809393f84ad5
+//
 func (hash RadialVarianceHash) Compare(a, b gocv.Mat) float64 {
 	return float64(C.radialVarianceHashCompare(C.Mat(a.Ptr()), C.Mat(b.Ptr()),
 		C.double(hash.Sigma), C.int(hash.NumOfAngleLine)))