Metal每日分享，颜色转换滤镜效果 |
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Metal每日分享，颜色转换滤镜效果
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本案例的目的是理解如何用Metal实现像素颜色转换滤镜，通过对像素颜色的不同读取方式获取到相应像素颜色，灰度图移除场景中除了黑白灰以外所有的颜色，让整个图像灰度化； 效果图
WX20221121-165812.png
实操代码
// 转成灰度图滤镜
let filter = C7ColorConvert(with: .gray)
// 方案1:
let dest = BoxxIO.init(element: originImage, filter: filter)
ImageView.image = try? dest.output()
dest.filters.forEach {
NSLog("%@", "\($0.parameterDescription)")
}
// 方案2:
ImageView.image = try? originImage.make(filter: filter)
// 方案3:
ImageView.image = originImage ->> filter
实现原理
过滤器
这款滤镜采用并行计算编码器设计.compute(kernel: "C7ColorConvert") /// 颜色通道`RGB`位置转换 public struct C7ColorConvert: C7FilterProtocol { public enum ColorType: String, CaseIterable { case invert = "C7ColorInvert" case gray = "C7Color2Gray" case bgra = "C7Color2BGRA" case brga = "C7Color2BRGA" case gbra = "C7Color2GBRA" case grba = "C7Color2GRBA" case rbga = "C7Color2RBGA" } private let type: ColorType public var modifier: Modifier { return .compute(kernel: type.rawValue) } public init(with type: ColorType) { self.type = type } } 着色器取出像素rgb值，然后根据对应像素颜色；灰度图则是取所有的颜色分量，将它们加权或平均； // 颜色反转，1 - rgb kernel void C7ColorInvert(texture2d outputTexture [[texture(0)]], texture2d inputTexture [[texture(1)]], uint2 grid [[thread_position_in_grid]]) { const half4 inColor = inputTexture.read(grid); const half4 outColor(1.0h - inColor.rgb, inColor.a); outputTexture.write(outColor, grid); } // 转灰度图 kernel void C7Color2Gray(texture2d outputTexture [[texture(0)]], texture2d inputTexture [[texture(1)]], uint2 grid [[thread_position_in_grid]]) { const half4 inColor = inputTexture.read(grid); const half3 kRec709Luma = half3(0.2126, 0.7152, 0.0722); const half gray = dot(inColor.rgb, kRec709Luma); const half4 outColor = half4(half3(gray), 1.0h); outputTexture.write(outColor, grid); } kernel void C7Color2BGRA(texture2d outputTexture [[texture(0)]], texture2d inputTexture [[texture(1)]], uint2 grid [[thread_position_in_grid]]) { const half4 inColor = inputTexture.read(grid); const half4 outColor(inColor.bgr, inColor.a); outputTexture.write(outColor, grid); } kernel void C7Color2BRGA(texture2d outputTexture [[texture(0)]], texture2d inputTexture [[texture(1)]], uint2 grid [[thread_position_in_grid]]) { const half4 inColor = inputTexture.read(grid); const half4 outColor(inColor.brg, inColor.a); outputTexture.write(outColor, grid); } kernel void C7Color2GBRA(texture2d outputTexture [[texture(0)]], texture2d inputTexture [[texture(1)]], uint2 grid [[thread_position_in_grid]]) { const half4 inColor = inputTexture.read(grid); const half4 outColor(inColor.gbr, inColor.a); outputTexture.write(outColor, grid); } kernel void C7Color2GRBA(texture2d outputTexture [[texture(0)]], texture2d inputTexture [[texture(1)]], uint2 grid [[thread_position_in_grid]]) { const half4 inColor = inputTexture.read(grid); const half4 outColor(inColor.grb, inColor.a); outputTexture.write(outColor, grid); } kernel void C7Color2RBGA(texture2d outputTexture [[texture(0)]], texture2d inputTexture [[texture(1)]], uint2 grid [[thread_position_in_grid]]) { const half4 inColor = inputTexture.read(grid); const half4 outColor(inColor.rbg, inColor.a); outputTexture.write(outColor, grid); } 多滤镜联动
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