diff --git a/.github/workflows/release.yml b/.github/workflows/release.yml
index ec76ca4..7545fde 100644
--- a/.github/workflows/release.yml
+++ b/.github/workflows/release.yml
@@ -13,7 +13,7 @@ jobs:
     strategy:
       fail-fast: true
       matrix:
-        go: [1.14]
+        go: [1.16]
 
     steps:
       - name: Checkout
diff --git a/color_16.go b/color_16.go
index 28e1048..f2a211a 100644
--- a/color_16.go
+++ b/color_16.go
@@ -42,10 +42,12 @@ func (o Opts) String() string {
  *************************************************************/
 
 // Base value for foreground/background color
+// base: fg 30~37, bg 40~47
+// light: fg 90~97, bg 100~107
 const (
 	FgBase uint8 = 30
 	BgBase uint8 = 40
-	// hi color base code
+
 	HiFgBase uint8 = 90
 	HiBgBase uint8 = 100
 )
@@ -240,6 +242,7 @@ func (c Color) Println(a ...interface{}) {
 }
 
 // Light current color. eg: 36(FgCyan) -> 96(FgLightCyan).
+//
 // Usage:
 // 	lightCyan := Cyan.Light()
 // 	lightCyan.Print("message")
@@ -254,6 +257,7 @@ func (c Color) Light() Color {
 }
 
 // Darken current color. eg. 96(FgLightCyan) -> 36(FgCyan)
+//
 // Usage:
 // 	cyan := LightCyan.Darken()
 // 	cyan.Print("message")
@@ -291,6 +295,26 @@ func (c Color) C256() Color256 {
 	return Color256{val}
 }
 
+// ToFg always convert fg
+func (c Color) ToFg() Color {
+	val := uint8(c)
+	// is option code, don't change
+	if val < 10 {
+		return c
+	}
+	return Color(Bg2Fg(val))
+}
+
+// ToBg always convert bg
+func (c Color) ToBg() Color {
+	val := uint8(c)
+	// is option code, don't change
+	if val < 10 {
+		return c
+	}
+	return Color(Fg2Bg(val))
+}
+
 // RGB convert 16 color to 256-color code.
 func (c Color) RGB() RGBColor {
 	val := uint8(c)
@@ -426,6 +450,26 @@ var (
 	}
 )
 
+// Bg2Fg bg color value to fg value
+func Bg2Fg(val uint8) uint8 {
+	if val >= BgBase && val <= 47 { // is bg
+		val = val - 10
+	} else if val >= HiBgBase && val <= 107 { // is hi bg
+		val = val - 10
+	}
+	return val
+}
+
+// Fg2Bg fg color value to bg value
+func Fg2Bg(val uint8) uint8 {
+	if val >= FgBase && val <= 37 { // is fg
+		val = val + 10
+	} else if val >= HiFgBase && val <= 97 { // is hi fg
+		val = val + 10
+	}
+	return val
+}
+
 // Basic2nameMap data
 func Basic2nameMap() map[uint8]string {
 	return basic2nameMap
diff --git a/color_test.go b/color_test.go
index 1d74672..68df26f 100644
--- a/color_test.go
+++ b/color_test.go
@@ -333,6 +333,17 @@ func TestColor16(t *testing.T) {
 	is.True(ok)
 }
 
+func TestColor_convert(t *testing.T) {
+	assert.Equal(t, "36", Cyan.ToFg().Code())
+	assert.Equal(t, "46", Cyan.ToBg().Code())
+	assert.Equal(t, "46", BgCyan.ToBg().Code())
+	assert.Equal(t, "36", BgCyan.ToFg().Code())
+
+	assert.Equal(t, "106", HiCyan.ToBg().Code())
+	assert.Equal(t, "93", BgHiYellow.ToFg().Code())
+	assert.Equal(t, "105", BgHiMagenta.ToBg().Code())
+}
+
 func TestColor_C256(t *testing.T) {
 	assert.True(t, Bold.C256().IsEmpty())
 
diff --git a/convert.go b/convert.go
index dc37d6c..6e3326d 100644
--- a/convert.go
+++ b/convert.go
@@ -40,14 +40,15 @@ var (
 		35:  "c839c5", // magenta
 		36:  "20c5c6", // cyan
 		37:  "c7c7c7", // white
-		40:  "000000", // black
-		41:  "c51e14", // red
-		42:  "1dc121", // green
-		43:  "c7c329", // yellow
-		44:  "0a2fc4", // blue
-		45:  "c839c5", // magenta
-		46:  "20c5c6", // cyan
-		47:  "c7c7c7", // white
+		// - don't add bg color
+		// 40:  "000000", // black
+		// 41:  "c51e14", // red
+		// 42:  "1dc121", // green
+		// 43:  "c7c329", // yellow
+		// 44:  "0a2fc4", // blue
+		// 45:  "c839c5", // magenta
+		// 46:  "20c5c6", // cyan
+		// 47:  "c7c7c7", // white
 		90:  "686868", // lightBlack/darkGray
 		91:  "fd6f6b", // lightRed
 		92:  "67f86f", // lightGreen
@@ -56,14 +57,15 @@ var (
 		95:  "fd7cfc", // lightMagenta
 		96:  "68fdfe", // lightCyan
 		97:  "ffffff", // lightWhite
-		100: "686868", // lightBlack/darkGray
-		101: "fd6f6b", // lightRed
-		102: "67f86f", // lightGreen
-		103: "fffa72", // lightYellow
-		104: "6a76fb", // lightBlue
-		105: "fd7cfc", // lightMagenta
-		106: "68fdfe", // lightCyan
-		107: "ffffff", // lightWhite
+		// - don't add bg color
+		// 100: "686868", // lightBlack/darkGray
+		// 101: "fd6f6b", // lightRed
+		// 102: "67f86f", // lightGreen
+		// 103: "fffa72", // lightYellow
+		// 104: "6a76fb", // lightBlue
+		// 105: "fd7cfc", // lightMagenta
+		// 106: "68fdfe", // lightCyan
+		// 107: "ffffff", // lightWhite
 	}
 	// will convert data from basic2hexMap
 	hex2basicMap = initHex2basicMap()
@@ -467,12 +469,18 @@ func RgbToHex(rgb []int) string {
 
 // Basic2hex convert basic color to hex string.
 func Basic2hex(val uint8) string {
+	val = Fg2Bg(val)
 	return basic2hexMap[val]
 }
 
 // Hex2basic convert hex string to basic color code.
-func Hex2basic(hex string) uint8 {
-	return hex2basicMap[hex]
+func Hex2basic(hex string, asBg ...bool) uint8 {
+	val := hex2basicMap[hex]
+
+	if len(asBg) > 0 && asBg[0] {
+		return Fg2Bg(val)
+	}
+	return val
 }
 
 // Rgb2basic alias of the RgbToAnsi()
diff --git a/convert_test.go b/convert_test.go
index 61d6cc1..281b2c7 100644
--- a/convert_test.go
+++ b/convert_test.go
@@ -14,7 +14,8 @@ func TestRgb2basic(t *testing.T) {
 }
 
 func TestHex2basic(t *testing.T) {
-	assert.Equal(t, uint8(105), Hex2basic("fd7cfc"))
+	assert.Equal(t, uint8(95), Hex2basic("fd7cfc"))
+	assert.Equal(t, uint8(105), Hex2basic("fd7cfc", true))
 }
 
 func TestHslToRgb(t *testing.T) {
diff --git a/utils.go b/utils.go
index 830ad88..bfd1353 100644
--- a/utils.go
+++ b/utils.go
@@ -120,13 +120,13 @@ func Text(s string) string {
 }
 
 // Uint8sToInts convert []uint8 to []int
-func Uint8sToInts(u8s []uint8 ) []int {
-	ints := make([]int, len(u8s))
-	for i, u8 := range u8s {
-		ints[i] = int(u8)
-	}
-	return ints
-}
+// func Uint8sToInts(u8s []uint8 ) []int {
+// 	ints := make([]int, len(u8s))
+// 	for i, u8 := range u8s {
+// 		ints[i] = int(u8)
+// 	}
+// 	return ints
+// }
 
 /*************************************************************
  * helper methods for print