Metal每日分享，均值模糊滤镜效果-阿里云开发者社区

Metal每日分享，均值模糊滤镜效果

2023-01-17 105

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简介： Metal每日分享，均值模糊滤镜效果

Demo

HarbethDemo地址
iDay每日分享文档地址

实操代码

// 均值模糊效果滤镜
let filter = C7MeanBlur.init(radius: 0.5)
// 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: "C7MeanBlur")，参数因子[radius]

对外开放参数

radius: 调整模糊半径，其实就是调整模糊度。

/// 均值模糊效果
public struct C7MeanBlur: C7FilterProtocol {
    public var radius: Float = 1
    public var modifier: Modifier {
        return .compute(kernel: "C7MeanBlur")
    }
    public var factors: [Float] {
        return [radius]
    }
    public init(radius: Float = 1) {
        self.radius = radius
    }
}

着色器

对坐标点归一化处理，将颗粒半径缩小百倍，取像素点周边上下左右半径点像素，然后将4个像素点叠加合成以达到模糊效果；

kernel void C7MeanBlur(texture2d<half, access::write> outputTexture [[texture(0)]],
                       texture2d<half, access::sample> inputTexture [[texture(1)]],
                       constant float *blurRadius [[buffer(0)]],
                       uint2 grid [[thread_position_in_grid]]) {
    constexpr sampler quadSampler(mag_filter::linear, min_filter::linear);
    const float2 coordinate = float2(float(grid.x) / outputTexture.get_width(), float(grid.y) / outputTexture.get_height());
    const half radius = half(*blurRadius) / 100.0h;
    const half4 sample1 = inputTexture.sample(quadSampler, float2(coordinate.x - radius, coordinate.y - radius));
    const half4 sample2 = inputTexture.sample(quadSampler, float2(coordinate.x + radius, coordinate.y + radius));
    const half4 sample3 = inputTexture.sample(quadSampler, float2(coordinate.x + radius, coordinate.y - radius));
    const half4 sample4 = inputTexture.sample(quadSampler, float2(coordinate.x - radius, coordinate.y + radius));
    const half4 outColor = (sample1 + sample2 + sample3 + sample4) / 4.0h;
    outputTexture.write(outColor, grid);
}