Java，LibGDX - 高斯模糊颜色分离器问题 - 接收负值

Question

我一直在 java 和 libgdx 上研究高斯模糊。它主要工作...

This is the image that I am trying to blur.

This is the result.

问题是大多数情况下红色值等于 -1，而不是 255 之类的值。我搜索了很多论坛，但他们没有解决这个问题。我还注意到大多数人使用 ARGB8888 但 badlogics 库没有 ARGB8888 格式，它有 RGBA8888 格式。我还在网站上搜索了 RGBA8888 如何以位形式存储其信息，我了解了一些，但不足以解决问题。

import com.badlogic.gdx.Gdx;
import com.badlogic.gdx.graphics.Pixmap;
import com.badlogic.gdx.graphics.PixmapIO;
import com.badlogic.gdx.utils.BufferUtils;
import com.badlogic.gdx.utils.ScreenUtils;

import java.awt.image.ConvolveOp;
import java.nio.ByteBuffer;


public class ScreenCapture {
    public void capture(){
        float output = 0;

        int[] all = new int[11];

        Pixmap originalPixmap = new Pixmap(Gdx.files.internal("graphics/menu/test.png"));

        Pixmap pixmapVertical = new Pixmap(originalPixmap.getWidth(), originalPixmap.getHeight(), Pixmap.Format.RGBA8888);
        Pixmap pixmap = new Pixmap(pixmapVertical.getWidth(), pixmapVertical.getHeight(), Pixmap.Format.RGBA8888);

        for (int y = 0;y < originalPixmap.getHeight();y++){
            for (int x = 0;x < originalPixmap.getWidth();x++){
                for (int i = -5; i < 5; i++) {
                    all[i+5] = originalPixmap.getPixel(x+i, y);
                }
                pixmapVertical.setColor(blur(all));
                pixmapVertical.drawPixel(x, y);
            }
        }
        for (int x = 0;x < pixmapVertical.getWidth();x++){
            for (int y = 0;y < pixmapVertical.getHeight();y++){

                for (int i = -5; i < 5; i++) {
                    all[i+5] = pixmapVertical.getPixel(x, y+i);
                }
                pixmap.setColor(blur(all));
                pixmap.drawPixel(x, y);
            }
        }


        PixmapIO.writePNG(Gdx.files.local("screen.png"), pixmap);
        originalPixmap.dispose();
        pixmapVertical.dispose();
        pixmap.dispose();

        int rgb = 0xffffffff;
        int test = ((rgb & 0xff000000) >> 24);
        System.out.println(test);

    }
    private int blur(int[] all){
        float[] weight = {0.0093f, 0.028002f, 0.065984f, 0.121703f, 0.175713f, 0.198596f, 0.175713f, 0.121703f, 0.065984f, 0.028002f, 0.0093f};
        float r = 0;
        float g = 0;
        float b = 0;
        float a = 0;
        for (int i = 0; i < 11; i++){
            b +=  ( ((all[i] & 0x0000ff00)>>8)*weight[i]);
            r +=  ( ( (all[i] & 0xff000000)>>24 )*weight[i]);
            g +=  ( ((all[i] & 0x00ff0000)>>16)*weight[i]);
            a +=  ( ((all[i] & 0x000000ff))*weight[i]);
        }
        return (((int) r << 24 | (int)g << 16 | (int)b << 8 | (int)a ));
    }
}

Answer 1

最左边的值会导致你的数字为负数。例如。当红色为 255 时，您的数字为负数。您可以通过 &'ing 255 来避免这种情况。

int r += ( ( (all[i]>>24) & 0xff) )*weight[i]);

本质上是-1&0xff = 255

还有无符号右移运算符>>>，它会给你相同的结果。

int r += ( (all[i]>>>24) )*weight[i]);