fix: reduce graining caused by contrast boost & fine detail overload

banner.go

@@ -298,23 +298,23 @@ func findTextPositions(textData []*TextData, filename string) {
 	}
 }
 
-func genPerlinBG() *image.RGBA {
+func genPerlinBG() (*image.RGBA, string) {
 	palette, theme := getRandomThemePalette()
 	img := image.NewRGBA(image.Rect(0, 0, config.BannerWidth, config.BannerHeight))
 
 	// noise params for interesting patterns
-	scale1 := 0.005 + rand.Float64()*0.025 // primary pattern scale (adjusted by lib)
+	scale1 := 0.008 + rand.Float64()*0.015 // 0.008-0.023 (large patterns)
-	scale2 := 0.02 + rand.Float64()*0.04   // secondary detail
+	scale2 := 0.025 + rand.Float64()*0.035 // 0.025-0.06 (medium detail)
-	scale3 := 0.06 + rand.Float64()*0.08   // fine detail
+	scale3 := 0.060 + rand.Float64()*0.040 // 0.060-0.100 (fine detail, reduced grain)
 
 	// variation offsets
 	offsetX := rand.Float64() * 5000
 	offsetY := rand.Float64() * 5000
 
 	// noise layer weights for different effects
-	weight1 := 0.4 + rand.Float64()*0.4
+	weight1 := 0.4 + rand.Float64()*0.4   // 0.4-0.8 (large patterns)
-	weight2 := 0.2 + rand.Float64()*0.3
+	weight2 := 0.15 + rand.Float64()*0.25 // 0.15-0.4 (medium detail)
-	weight3 := 0.1 + rand.Float64()*0.2
+	weight3 := 0.05 + rand.Float64()*0.15 // 0.15-0.4 (fine detail, reduced grain)
 
 	// normalize weights to sum to 1.0
 	totalWeight := weight1 + weight2 + weight3
@@ -322,8 +322,9 @@ func genPerlinBG() *image.RGBA {
 	weight2 /= totalWeight
 	weight3 /= totalWeight
 
-	gradientStrengthX := rand.Float64() * 0.4
+	// FIX: limit gradient strength to prevent overwhelming the noise
-	gradientStrengthY := rand.Float64() * 0.3
+	gradientStrengthX := rand.Float64() * 0.25 // old: 0.4
+	gradientStrengthY := rand.Float64() * 0.2  // old: 0.3
 	gradientDirectionX := 1.0
 	gradientDirectionY := 1.0
 
@@ -338,8 +339,9 @@ func genPerlinBG() *image.RGBA {
 	// randomize noise combination method
 	combineMethod := rand.IntN(4)
 
-	useDistortion := rand.Float64() < 0.3 // 30% chance
+	// fix: increase distortion chance and make it more visible
-	distortionStrength := rand.Float64() * 0.1
+	useDistortion := rand.Float64() < 0.4            // old: 30%
+	distortionStrength := 0.05 + rand.Float64()*0.15 // 0.05-0.2 (old: 0.0-0.1)
 
 	log.Debugf("BG theme: %s / Scales: %.4f, %.4f, %.4f / Weights: %.3f, %.3f, %.3f",
 		theme, scale1, scale2, scale3, weight1, weight2, weight3)
@@ -354,8 +356,8 @@ func genPerlinBG() *image.RGBA {
 
 			// optional distortion for more organic patterns
 			if useDistortion {
-				baseX += math.Sin(float64(y)*0.01) * distortionStrength * 100
+				baseX += math.Sin(float64(y)*0.015) * distortionStrength * 200
-				baseY += math.Cos(float64(x)*0.01) * distortionStrength * 100
+				baseY += math.Cos(float64(x)*0.015) * distortionStrength * 200
 			}
 
 			// multi-octave noise with randomized scales
@@ -390,28 +392,19 @@ func genPerlinBG() *image.RGBA {
 			gradientY := (float64(y) / float64(config.BannerHeight)) * gradientStrengthY * gradientDirectionY
 
 			// combined and normalized to [0, 1] range
-			noise := (combined + gradientX + gradientY + 1) / 2
+			noise := min(max((combined+gradientX+gradientY+1)/2, 0), 1)
-
-			// clamp to valid range
-			if noise < 0 {
-				noise = 0
-			}
-			if noise > 1 {
-				noise = 1
-			}
 
 			pixelColor := palette.interpolate(noise)
 			img.Set(x, y, pixelColor)
 		}
 	}
 
-	return img
+	return img, theme
 }
 
 func genBanner(textData []*TextData) error {
 	fn := fmt.Sprintf("banner_%d.png", time.Now().UnixMicro())
-	canvas := genPerlinBG()
+	canvas, theme := genPerlinBG()
-
 	findTextPositions(textData, fn)
 
 	for _, td := range textData {
@@ -428,7 +421,13 @@ func genBanner(textData []*TextData) error {
 	}
 	defer file.Close()
 
-	return png.Encode(file, canvas)
+	if err := png.Encode(file, canvas); err != nil {
+		return err
+	}
+
+	log.Infof("Output '%s' with theme '%s'", fn, theme)
+
+	return nil
 }
 
 // TODO: functions for banner rotation implementation