diff --git a/Makefile b/Makefile
index fd3b19b..92ad903 100755
--- a/Makefile
+++ b/Makefile
@@ -40,6 +40,6 @@ lint:
 	golint .
 
 clean:
-	rm -f build
-	rm -rf internal/resources
+	- rm -r build
+	- rm -rf internal/resources
 
diff --git a/gopow.go b/gopow.go
index f59cba9..67eae4b 100644
--- a/gopow.go
+++ b/gopow.go
@@ -14,7 +14,7 @@ func main() {
 	app := cli.NewApp()
 	app.Name = "RTL GoPow"
 	app.Usage = "Render a rtl_power CSV output as waterfall image"
-	app.Version = "0.0.2"
+	app.Version = "0.0.3"
 	app.Author = "github.com/dhogborg"
 	app.Email = "d@hogborg.se"
 
@@ -68,6 +68,16 @@ func main() {
 			Value: "png",
 			Usage: "Output file format, default png [png,jpeg]",
 		},
+		cli.Float64Flag{
+			Name:  "max-power",
+			Value: 0,
+			Usage: "Define a manual maximum power (format nn.n)",
+		},
+		cli.Float64Flag{
+			Name:  "min-power",
+			Value: 0,
+			Usage: "Define a manual minimum power (format nn.n)",
+		},
 		cli.BoolFlag{
 			Name:  "verbose",
 			Usage: "Enable more verbose output",
diff --git a/internal/gopow/gopow.go b/internal/gopow/gopow.go
index e0c8fd6..fc3674a 100644
--- a/internal/gopow/gopow.go
+++ b/internal/gopow/gopow.go
@@ -13,11 +13,17 @@ import (
 	"github.com/dustin/go-humanize"
 )
 
+const (
+	PowerConfigAuto = -9813
+)
+
 type RunConfig struct {
 	InputFile   string
 	OutputFile  string
 	Format      string
 	Annotations bool
+	MaxPower    float64
+	MinPower    float64
 }
 
 type GoPow struct {
@@ -33,6 +39,15 @@ func NewGoPow(c *cli.Context) (*GoPow, error) {
 		OutputFile:  c.String("output"),
 		Format:      c.String("format"),
 		Annotations: !c.Bool("no-annotations"),
+		MaxPower:    c.Float64("max-power"),
+		MinPower:    c.Float64("min-power"),
+	}
+
+	if !c.IsSet("max-power") {
+		config.MaxPower = PowerConfigAuto
+	}
+	if !c.IsSet("min-power") {
+		config.MinPower = PowerConfigAuto
 	}
 
 	if config.InputFile == "" {
@@ -66,10 +81,20 @@ func NewGoPow(c *cli.Context) (*GoPow, error) {
 
 func (g *GoPow) Render() error {
 
+	conf := &RenderConfig{}
+
+	if g.config.MaxPower != PowerConfigAuto {
+		conf.MaxPower = &g.config.MaxPower
+	}
+
+	if g.config.MinPower != PowerConfigAuto {
+		conf.MinPower = &g.config.MinPower
+	}
+
 	log.Debug("staring render")
 	g.timestamp = time.Now()
 
-	table, err := NewTable(g.config.InputFile)
+	table, err := NewTable(g.config.InputFile, conf)
 	if err != nil {
 		return err
 	}
@@ -77,7 +102,7 @@ func (g *GoPow) Render() error {
 	g.image = table.Image()
 
 	for y, row := range table.Rows {
-		for x, _ := range row.Samples {
+		for x := range row.Samples {
 			g.image.Set(x, y, table.ColorAt(x, y))
 		}
 	}
diff --git a/internal/gopow/table.go b/internal/gopow/table.go
index eb46778..f3bcd22 100644
--- a/internal/gopow/table.go
+++ b/internal/gopow/table.go
@@ -16,13 +16,11 @@ import (
 )
 
 type TableComplex struct {
-	File string // our input file
+	File   string // our input file
+	Config *RenderConfig
 
 	Rows []*LineComplex
 
-	Min float64 // minimum power value, used for color rendering
-	Max float64 // maximum dito
-
 	Bins         int // horizontal slots, columns, bandwidth
 	Integrations int // vertical slots, rows
 
@@ -33,11 +31,19 @@ type TableComplex struct {
 	TimeEnd   *time.Time
 }
 
-func NewTable(file string) (*TableComplex, error) {
+// RenderConfig overrides automaticly calculated defaults
+type RenderConfig struct {
+	MinPower *float64 // minimum power value, used for color rendering
+	MaxPower *float64 // maximum dito
+}
+
+func NewTable(file string, conf *RenderConfig) (*TableComplex, error) {
 
 	log.Debug("creating table")
 
-	t := &TableComplex{}
+	t := &TableComplex{
+		Config: conf,
+	}
 
 	err := t.Load(file)
 	if err != nil {
@@ -70,8 +76,8 @@ func (t *TableComplex) Load(file string) error {
 
 func (t *TableComplex) parseBuffer(filebuffer []byte) []*LineComplex {
 
-	t.Max = float64(math.MaxFloat64 * -1)
-	t.Min = float64(math.MaxFloat64)
+	var max = float64(math.MaxFloat64 * -1)
+	var min = float64(math.MaxFloat64)
 
 	lines := bytes.Split(filebuffer, []byte("\n"))
 
@@ -100,11 +106,11 @@ func (t *TableComplex) parseBuffer(filebuffer []byte) []*LineComplex {
 
 			rows = append(rows, row)
 
-			if t.Min > row.LowSample() {
-				t.Min = row.LowSample()
+			if min > row.LowSample() {
+				min = row.LowSample()
 			}
-			if t.Max < row.HighSample() {
-				t.Max = row.HighSample()
+			if max < row.HighSample() {
+				max = row.HighSample()
 			}
 
 			t.HzLow = row.HzLow
@@ -134,9 +140,17 @@ func (t *TableComplex) parseBuffer(filebuffer []byte) []*LineComplex {
 
 	sort.Sort(LineSort(rows))
 
+	if t.Config.MaxPower == nil {
+		t.Config.MaxPower = &max
+	}
+
+	if t.Config.MinPower == nil {
+		t.Config.MinPower = &min
+	}
+
 	log.WithFields(log.Fields{
-		"pMax": t.Max,
-		"pMin": t.Min,
+		"pMax": *t.Config.MaxPower,
+		"pMin": *t.Config.MinPower,
 	}).Debug("integrated lines")
 
 	t.Integrations = len(rows)
@@ -185,14 +199,21 @@ func (t *TableComplex) ColorAt(x, y int) color.Color {
 
 	cell := t.Rows[y].Sample(x)
 
-	hue_start := 236.0
-	hue_end := 0.0
+	hueStart := 236.0
+	hueEnd := 0.0
 
-	span := (t.Min - t.Max) * -1
-	h_per_deg := (hue_start - hue_end) / span
-	pow_normalized := cell - t.Min
-	pow_degrees := pow_normalized * h_per_deg
-	hue := hue_start - pow_degrees
+	span := (*t.Config.MinPower - *t.Config.MaxPower) * -1
+	hPerDeg := (hueStart - hueEnd) / span
+	powNormalized := cell - *t.Config.MinPower
+	powDegrees := powNormalized * hPerDeg
+	hue := hueStart - powDegrees
+
+	if hue > hueStart {
+		hue = hueStart
+	}
+	if hue < hueEnd {
+		hue = hueEnd
+	}
 
 	return colorful.Hsv(hue, 1, 0.90)