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Finding and displaying a colour accent from an image https://forum.lowyat.net/topic/4908702/+0&#entry95561089
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| package main | |
| // https://forum.lowyat.net/index.php?act=ST&f=12&t=4908702&st=0 | |
| import ( | |
| "fmt" | |
| "image/jpeg" | |
| "log" | |
| "math" | |
| "os" | |
| gocolor "github.com/gerow/go-color" | |
| ) | |
| func main() { | |
| // cf https://pictr.com/image/5FrO4v | |
| inFile := "5FrPh2.md.jpg" | |
| r, err := os.Open(inFile) | |
| if err != nil { | |
| log.Fatal(err) | |
| } | |
| img, err := jpeg.Decode(r) | |
| if err != nil { | |
| log.Fatal(err) | |
| } | |
| // log.Printf("%+v\n", img) | |
| bound := img.Bounds() | |
| // log.Printf("%d %d\n", bound.Max.X, bound.Max.Y) | |
| counts := make(map[gocolor.HSL]float64) | |
| for y := 0; y < bound.Max.Y; y++ { | |
| for x := 0; x < bound.Max.X; x++ { | |
| pixel := img.At(x, y) | |
| r, g, b, a := pixel.RGBA() | |
| if a < 65535 { | |
| continue // Not doing alpha | |
| } | |
| rgb := gocolor.RGB{float64(r) / 65535, float64(g) / 65535, float64(b) / 65535.0} | |
| hsv := rgb.ToHSL() | |
| // log.Printf("%d %d %d %d", r, g, b, a) | |
| // log.Printf(" %d %d %d %d\n", hsv.H, hsv.L, hsv.S) | |
| if hsv.L < 0.0001 { | |
| continue | |
| } | |
| hsv.S = math.Round(hsv.S*256) / 256 | |
| hsv.H = math.Round(hsv.H*256) / 256 | |
| intensity := hsv.L | |
| hsv.L = 0 | |
| // Reject boring grays | |
| if hsv.S < 0.3 { | |
| continue | |
| } | |
| counts[hsv] += intensity | |
| // log.Printf("%d %d %d %d\n", r, g, b, a) | |
| } | |
| } | |
| // Find brightest | |
| // log.Println(counts) | |
| brigtestHSV := gocolor.HSL{} | |
| for k, v := range counts { | |
| // Take grayness (aka saturation) into account too. | |
| if brigtestHSV.L < v*k.S { | |
| // Yeah, need copy, not reference a moving struct | |
| brigtestHSV.H = k.H | |
| brigtestHSV.S = k.S | |
| brigtestHSV.L = v * k.S | |
| // copy(brightestHSV, k) | |
| } | |
| } | |
| colors := "" | |
| for l := 0.0; l < 1; l += 0.1 { | |
| brigtestHSV.L = l | |
| rgb := brigtestHSV.ToRGB() | |
| colors += fmt.Sprintf("<div%%20style='background:%%23%02x%02x%02x;'>Accent</div>", int(rgb.R*255), int(rgb.G*255), int(rgb.B*255)) | |
| } | |
| fmt.Println("Copy paste this to browser:") | |
| fmt.Printf("data:text/html,<html><body>%s</body></html>\n", colors) | |
| } |
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