Android基于OpenCV实现图像脱色

tangjin

作者

脱色

Imgproc.cvtColor(rgb, gray, Imgproc.COLOR_RGB2GRAY)可以快速的实现图片脱色，其通过简单的计算将三通道图像转换成单通道图像，经典的灰度转换公式如下：

但是转换过的图像存在对比度丢失，无法区分颜色的问题。OpenCV给我们提供另外一种脱色方法Photo.decolor，旨在最大限度的保留图片对比度。

原理

论文详情：www.cse.cuhk.edu.hk/~leojia/pro…

论文PDF：www.computer.org/csdl/pds/ap…

相比于简单的使用R/G/B线性组合，作者构造了更为复杂的多项式拟合，向量空间的基底为：[r,g,b,rg,rb,gb,r2,g2,b2]，核心就是求取灰度化函数：

API

public static void decolor(Mat src, Mat grayscale, Mat color_boost)

操作

/**
 * 脱色
 * author: yidong
 * 2020/12/5
 */
class DecolorActivity : AppCompatActivity() {

    private val mBinding: ActivityDecolorBinding by lazy {
        ActivityDecolorBinding.inflate(layoutInflater)
    }

    private val mList = mutableListOf<ImageTextObject>()
    private lateinit var mAdapter: ImageTextAdapter

    override fun onCreate(savedInstanceState: Bundle?) {
        super.onCreate(savedInstanceState)
        setContentView(mBinding.root)
        mAdapter = ImageTextAdapter(this, mList)
        mBinding.container.adapter = mAdapter
        val bgr = Utils.loadResource(this, R.drawable.ceil)
        val rgb = Mat()
        Imgproc.cvtColor(bgr, rgb, Imgproc.COLOR_BGR2RGB)
        val gray = Mat()
        val dst = Mat()
        val boost = Mat()
        mBinding.isLoading = true
        GlobalScope.launch(Dispatchers.IO) {
            Imgproc.cvtColor(rgb, gray, Imgproc.COLOR_RGB2GRAY)
            Photo.decolor(rgb, dst, boost)
            launch(Dispatchers.Main) {
                mList.add(ImageTextObject(rgb, "原图"))
                mList.add(ImageTextObject(gray, "RGB2GRAY"))
                mList.add(ImageTextObject(dst, "DeColor"))
                mList.add(ImageTextObject(boost, "ColorBoosting"))
                mAdapter.notifyItemRangeInserted(0, 4)
                mBinding.isLoading = false
            }
        }
    }
}