103 lines
3.5 KiB
Kotlin
103 lines
3.5 KiB
Kotlin
package kr.co.vividnext.sodalive.utils
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import java.awt.image.BufferedImage
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import kotlin.math.exp
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import kotlin.math.max
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import kotlin.math.min
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/**
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* 가우시안 커널 기반 블러 유틸리티
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* - 반경(radius)에 따라 커널 크기(2*radius+1) 생성
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* - 시그마는 관례적으로 radius/3.0 적용
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* - 수평/수직 분리 합성곱으로 품질과 성능 확보
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*/
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object ImageBlurUtil {
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fun blur(src: BufferedImage, radius: Int = 10): BufferedImage {
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require(radius > 0) { "radius must be > 0" }
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val w = src.width
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val h = src.height
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val dst = BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB)
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// 가우시안 1D 커널 생성 및 정규화
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val sigma = radius / 3.0
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val kernel = gaussianKernel(radius, sigma)
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// 중간 버퍼
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val temp = BufferedImage(w, h, BufferedImage.TYPE_INT_ARGB)
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// 수평 합성곱
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for (y in 0 until h) {
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for (x in 0 until w) {
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var aAcc = 0.0
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var rAcc = 0.0
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var gAcc = 0.0
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var bAcc = 0.0
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for (k in -radius..radius) {
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val xx = clamp(x + k, 0, w - 1)
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val rgb = src.getRGB(xx, y)
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val a = (rgb ushr 24) and 0xFF
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val r = (rgb ushr 16) and 0xFF
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val g = (rgb ushr 8) and 0xFF
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val b = rgb and 0xFF
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val wgt = kernel[k + radius]
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aAcc += a * wgt
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rAcc += r * wgt
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gAcc += g * wgt
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bAcc += b * wgt
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}
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val a = aAcc.toInt().coerceIn(0, 255)
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val r = rAcc.toInt().coerceIn(0, 255)
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val g = gAcc.toInt().coerceIn(0, 255)
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val b = bAcc.toInt().coerceIn(0, 255)
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temp.setRGB(x, y, (a shl 24) or (r shl 16) or (g shl 8) or b)
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}
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}
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// 수직 합성곱
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for (x in 0 until w) {
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for (y in 0 until h) {
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var aAcc = 0.0
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var rAcc = 0.0
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var gAcc = 0.0
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var bAcc = 0.0
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for (k in -radius..radius) {
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val yy = clamp(y + k, 0, h - 1)
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val rgb = temp.getRGB(x, yy)
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val a = (rgb ushr 24) and 0xFF
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val r = (rgb ushr 16) and 0xFF
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val g = (rgb ushr 8) and 0xFF
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val b = rgb and 0xFF
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val wgt = kernel[k + radius]
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aAcc += a * wgt
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rAcc += r * wgt
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gAcc += g * wgt
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bAcc += b * wgt
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}
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val a = aAcc.toInt().coerceIn(0, 255)
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val r = rAcc.toInt().coerceIn(0, 255)
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val g = gAcc.toInt().coerceIn(0, 255)
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val b = bAcc.toInt().coerceIn(0, 255)
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dst.setRGB(x, y, (a shl 24) or (r shl 16) or (g shl 8) or b)
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}
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}
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return dst
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}
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private fun gaussianKernel(radius: Int, sigma: Double): DoubleArray {
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val size = 2 * radius + 1
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val kernel = DoubleArray(size)
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val sigma2 = 2.0 * sigma * sigma
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var sum = 0.0
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for (i in -radius..radius) {
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val v = exp(-(i * i) / sigma2)
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kernel[i + radius] = v
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sum += v
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}
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// 정규화
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for (i in kernel.indices) kernel[i] /= sum
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return kernel
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}
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private fun clamp(v: Int, lo: Int, hi: Int): Int = max(lo, min(hi, v))
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}
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