diff --git a/convert/image/convert.go b/convert/image/convert.go
index 58f9895..729b700 100644
--- a/convert/image/convert.go
+++ b/convert/image/convert.go
@@ -238,7 +238,14 @@ func downgradeWithPalette(in *image.NRGBA, p color.Palette) *image.NRGBA {
 			if cc := cache[c]; cc != nil {
 				in.Set(x, y, cc)
 			} else {
-				cPalette := p.Convert(c)
+				var cPalette color.Color
+				// check value transparency
+				r, g, b, a := c.RGBA()
+				if r == 0 && g == 0 && b == 0 && a == 0 {
+					cPalette = p[0]
+				} else {
+					cPalette = p.Convert(c)
+				}
 				in.Set(x, y, cPalette)
 				cache[c] = cPalette
 			}
diff --git a/ui/martine-ui/sprite_tab.go b/ui/martine-ui/sprite_tab.go
index 8a9576a..b6ca7b3 100644
--- a/ui/martine-ui/sprite_tab.go
+++ b/ui/martine-ui/sprite_tab.go
@@ -264,7 +264,11 @@ func (m *MartineUI) newSpriteTab(s *menu.SpriteMenu) *fyne.Container {
 				),
 			),
 			container.New(
-				layout.NewGridLayoutWithRows(2),
+				layout.NewGridLayoutWithRows(3),
+				container.New(layout.NewVBoxLayout(),
+					widget.NewCheck("Use this palette", func(b bool) {
+						s.UsePalette = b
+					})),
 				container.New(
 					layout.NewVBoxLayout(),
 					widget.NewLabel("Palette"),