cmd

cmd/negate/minus19blue.go

@@ -0,0 +1,39 @@
+//go:build ignore
+
+package main
+
+import (
+	"image"
+	"image/color"
+	"image/png"
+	"os"
+)
+
+type Reshade struct{ image.Image }
+
+func (rs Reshade) ColorModel() color.Model { return rs.Image.ColorModel() }
+func (rs Reshade) Bounds() image.Rectangle { return rs.Image.Bounds() }
+func (rs Reshade) At(x, y int) color.Color {
+	c := rs.Image.At(x, y)
+	r, g, b, a := c.RGBA()
+	// minus 19 blue
+	return color.RGBA{
+		uint8(r >> 8),
+		uint8(g >> 8),
+		uint8(b>>8) - 8*8,
+		uint8(a >> 8),
+	}
+}
+
+func check(err error) {
+	if err != nil {
+		panic(err)
+	}
+}
+
+func main() {
+	img, err := png.Decode(os.Stdin)
+	check(err)
+	err = png.Encode(os.Stdout, Reshade{img})
+	check(err)
+}