diff --git a/filter/basic.go b/filter/basic.go
index 3aeca7db..587facfe 100644
--- a/filter/basic.go
+++ b/filter/basic.go
@@ -99,7 +99,7 @@ func (bf *Basic) Write(f []byte) (int, error) {
 		return 0, fmt.Errorf("image can't be decoded: %w", err)
 	}
 
-	// First frame must be set as the first background image
+	// First frame must be set as the first background image.
 	if bf.bg == nil {
 		bounds := bf.img.Bounds()
 		bf.w = bounds.Max.X
@@ -153,7 +153,7 @@ func (bf *Basic) Write(f []byte) (int, error) {
 	return bf.dst.Write(f)
 }
 
-// Go routine for one row of the image to be processed
+// Go routine for one row of the image to be processed.
 func (bf *Basic) process(j int, wg *sync.WaitGroup) {
 	for i, _ := range bf.bg[j] {
 		n := bf.img.At(i, j)
@@ -186,6 +186,7 @@ func (bf *Basic) process(j int, wg *sync.WaitGroup) {
 	wg.Done()
 }
 
+// Writes a visualisation of the motion being detected to file.
 func (bf *Basic) saveFrame() error {
 	col := color.RGBA{200, 100, 0, 255} // Red text.
 	d := &font.Drawer{
@@ -204,6 +205,7 @@ func (bf *Basic) saveFrame() error {
 	return jpeg.Encode(bf.file, bf.bwImg, nil)
 }
 
+// Returns the absolute value of the difference of two uint32 numbers.
 func absDiff(a, b uint32) int {
 	c := int(a) - int(b)
 	if c < 0 {