FM effect

main.go

package main

import (
	"image"
	"image/color"
	"math"

	"github.com/anthonynsimon/bild/blend"
	"github.com/anthonynsimon/bild/fcolor"
	"github.com/anthonynsimon/bild/imgio"
	"github.com/anthonynsimon/bild/transform"
	"github.com/setanarut/apng"
)

func processImageFrames(img image.Image, freqMultiplier float64, frameCount int) []image.Image {
	bounds := img.Bounds()
	width, height := bounds.Max.X, bounds.Max.Y
	frames := make([]image.Image, frameCount)
	minOmega := 2 * math.Pi / (0.05 * float64(width))
	baseOmega := minOmega * freqMultiplier
	for frame := range frames {
		destImg := image.NewRGBA(bounds)
		frames[frame] = destImg
		// Time progression - normalized value for the loop (between 0-1)
		timeOffset := float64(frame) / float64(frameCount) * 2 * math.Pi * 1
		for y := range height {
			rf := 0.0
			gf := 0.0
			bf := 0.0
			for x := range width {
				r, g, b, _ := img.At(x, y).RGBA()

				rf += float64(r)/65535.0 - 1
				gf += float64(g)/65535.0 - 1
				bf += float64(b)/65535.0 - 1

				// Add time progression
				rm := math.Cos(baseOmega*float64(x) + rf + timeOffset)
				gm := math.Cos(baseOmega*float64(x) + gf + timeOffset)
				bm := math.Cos(baseOmega*float64(x) + bf + timeOffset)

				// Remap signal back to channel value
				rv := uint8(min(max((rm+1)*127.5, 0), 255))
				gv := uint8(min(max((gm+1)*127.5, 0), 255))
				bv := uint8(min(max((bm+1)*127.5, 0), 255))

				destImg.SetRGBA(x, y, color.RGBA{rv, gv, bv, 255})
			}
		}
	}
	for i := range frames {
		frames[i] = blend.Blend(frames[i], img, HardMix)
		frames[i] = transform.Resize(frames[i], width/2, height/2, transform.CatmullRom)

	}
	return frames
}

func main() {
	img, _ := imgio.Open("input.jpg")
	frames := processImageFrames(img, 5, 8)
	apng.Save("out.png", frames, 7)
}

func HardMix(c1, c2 fcolor.RGBAF64) (result fcolor.RGBAF64) {
	f := func(i, j float64) float64 {
		if j < 1-i {
			return 0
		}
		return 1
	}
	result.R = f(c1.R, c2.R)
	result.G = f(c1.G, c2.G)
	result.B = f(c1.B, c2.B)
	result.A = 1
	return result
}