Remove imaging functions. Those will be adapted for radolan2png

image.go

-package radolan
-
-import (
-	"image"
-	"image/color"
-	"math"
-)
-
-// A ColorFunc can be used to assign colors to rvp-6 values for image creation.
-type ColorFunc func(rvp RVP6) color.RGBA
-
-// Sample color and grayscale gradients for visualization with the image method.
-var (
-	// HeatmapReflectivity is a color gradient for cloud reflectivity composites
-	// between 5dBZ and 75dBZ.
-	HeatmapReflectivity ColorFunc
-
-	// HeatmapReflectivityWide is a color gradient for cloud reflectivity composites
-	// between -32.5dBZ and 75dBZ.
-	HeatmapReflectivityWide ColorFunc
-
-	// HeatmapAccumulatedHour is a color gradient for accumulated rainfall composites
-	// (e.g RW) between 0.1mm/h and 100 mm/h using logarithmic compression.
-	HeatmapAccumulatedHour ColorFunc
-
-	// HeatmapAccumulatedDay is a color gradient for accumulated rainfall composites
-	// (e.g. SF) between 0.1mm and 200mm using logarithmic compression.
-	HeatmapAccumulatedDay ColorFunc
-
-	// GraymapLinear is a linear grayscale gradient between the (raw) rvp-6
-	// values 0 and 409.5.
-	GraymapLinear ColorFunc
-
-	// GraymapLinearWide is a linear grayscale gradient between the (raw) rvp-6
-	// values 0 and 4095.
-	GraymapLinearWide ColorFunc
-)
-
-func init() {
-	// return identity (no compression)
-	id := func(x RVP6) RVP6 {
-		return x
-	}
-	// return logarithm
-	log := func(x RVP6) RVP6 {
-		return RVP6(math.Log(float64(x)))
-	}
-
-	HeatmapReflectivity = heatmap(DBZ(5.0).ToRVP6(), DBZ(75.0).ToRVP6(), id)
-	HeatmapReflectivityWide = heatmap(DBZ(-32.5).ToRVP6(), DBZ(75.0).ToRVP6(), id)
-	HeatmapAccumulatedHour = heatmap(0.1, 100, log)
-	HeatmapAccumulatedDay = heatmap(0.1, 200, log)
-
-	GraymapLinear = graymap(0, 409.5, id)
-	GraymapLinearWide = graymap(0, 4095, id)
-}
-
-// Image creates an image by evaluating the color function fn for each raw rvp-6 value.
-func (c *Composite) Image(fn ColorFunc) *image.RGBA {
-	rec := image.Rect(0, 0, c.Dx, c.Dy)
-	img := image.NewRGBA(rec)
-
-	for y := 0; y < c.Dy; y++ {
-		for x := 0; x < c.Dx; x++ {
-			img.Set(x, y, fn(c.Data[y][x]))
-		}
-	}
-
-	return img
-}
-
-// graymap returns a grayscale gradient between min and max. A compression function is used to
-// make logarithmic scales possible.
-func graymap(min, max RVP6, compression func(RVP6) RVP6) ColorFunc {
-	min = compression(min)
-	max = compression(max)
-
-	return func(rvp RVP6) color.RGBA {
-		rvp = compression(rvp)
-
-		if rvp < min {
-			return color.RGBA{0x00, 0x00, 0x00, 0xFF} // black
-		}
-
-		p := float64((rvp - min) / (max - min))
-		if p > 1 {
-			p = 1
-		}
-
-		l := uint8(0xFF * p)
-		return color.RGBA{l, l, l, 0xFF}
-	}
-}
-
-// heatmap returns a colour gradient between min and max. A compression function is used to
-// make logarithmic scales possible.
-func heatmap(min, max RVP6, compression func(RVP6) RVP6) ColorFunc {
-	min = compression(min)
-	max = compression(max)
-
-	return func(rvp RVP6) color.RGBA {
-		rvp = compression(rvp)
-		if rvp < min {
-			return color.RGBA{0x00, 0x00, 0x00, 0xFF} // black
-		}
-
-		p := float64((rvp - min) / (max - min))
-		if p > 1 { // limit
-			p = 1
-		}
-		h := math.Mod(360-(330*p)+240, 360)
-
-		s := 1.0          // saturation
-		l := 0.5*p + 0.25 // lightness
-
-		// adapted from https://en.wikipedia.org/wiki/HSL_and_HSV#From_HSL
-		c := (1 - math.Abs(2*l-1)) * s // calculate chroma
-
-		hh := h / 60
-		x := c * (1 - math.Abs(math.Mod(hh, 2)-1))
-
-		if math.IsNaN(hh) {
-			hh = -1
-		}
-
-		var rr, gg, bb float64
-		switch int(hh) {
-		case 0:
-			rr, gg, bb = c, x, 0
-		case 1:
-			rr, gg, bb = x, c, 0
-		case 2:
-			rr, gg, bb = 0, c, x
-		case 3:
-			rr, gg, bb = 0, x, c
-		case 4:
-			rr, gg, bb = x, 0, c
-		case 5:
-			rr, gg, bb = c, 0, x
-		}
-
-		m := l - c/2
-		r, g, b := uint8(0xFF*(rr+m)), uint8(0xFF*(gg+m)), uint8(0xFF*(bb+m))
-
-		return color.RGBA{r, g, b, 0xFF}
-	}
-}