Scales image using bilinear interpolation. - Java 2D Graphics

Java examples for 2D Graphics:BufferedImage Scale

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Description

Scales image using bilinear interpolation.

Demo Code


import java.io.InputStream;
import javax.microedition.lcdui.Image;
import javax.microedition.lcdui.game.Sprite;

public class Main{
    /**//from  w  ww.  j a va 2s.c  o m
     * Scales image using bilinear interpolation. Best suited for up scaling.
     * @return Returns scaled image
     */
    private static Image bilinearInterpolation(Image original,
            int newWidth, int newHeight) {
        int[] rawInput = new int[original.getHeight() * original.getWidth()];
        original.getRGB(rawInput, 0, original.getWidth(), 0, 0,
                original.getWidth(), original.getHeight());

        int[] rawOutput = new int[newWidth * newHeight];

        int oWidth = original.getWidth();
        int[] oX16 = new int[newWidth];
        int max = (oWidth - 1) << 4;
        for (int newX = 0; newX < newWidth; newX++) {
            oX16[newX] = ((((newX << 1) + 1) * oWidth) << 3) / newWidth - 8;
            if (oX16[newX] < 0) {
                oX16[newX] = 0;
            } else if (oX16[newX] > max) {
                oX16[newX] = max;
            }
        }

        int oHeight = original.getHeight();
        int[] oY16 = new int[newHeight];
        max = (oHeight - 1) << 4;
        for (int newY = 0; newY < newHeight; newY++) {
            oY16[newY] = ((((newY << 1) + 1) * oHeight) << 3) / newHeight
                    - 8;
            if (oY16[newY] < 0) {
                oY16[newY] = 0;
            } else if (oY16[newY] > max) {
                oY16[newY] = max;
            }
        }

        int[] oX = new int[2];
        int[] oY = new int[2];
        int[] wX = new int[2];
        int[] wY = new int[2];
        int outWeight, outColorWeight, outAlpha, outRed, outGreen, outBlue;
        int w, argb, a, r, g, b;
        for (int newY = 0; newY < newHeight; newY++) {
            oY[0] = oY16[newY] >>> 4;
            wY[1] = oY16[newY] & 0x0000000f;
            wY[0] = 16 - wY[1];
            oY[1] = wY[1] == 0 ? oY[0] : oY[0] + 1;
            for (int newX = 0; newX < newWidth; newX++) {
                oX[0] = oX16[newX] >>> 4;
                wX[1] = oX16[newX] & 0x0000000f;
                wX[0] = 16 - wX[1];
                oX[1] = wX[1] == 0 ? oX[0] : oX[0] + 1;

                outWeight = 0;
                outColorWeight = 0;
                outAlpha = 0;
                outRed = 0;
                outGreen = 0;
                outBlue = 0;
                for (int j = 0; j < 2; j++) {
                    for (int i = 0; i < 2; i++) {
                        if (wY[j] == 0 || wX[i] == 0) {
                            continue;
                        }
                        w = wX[i] * wY[j];
                        outWeight += w;
                        argb = rawInput[oX[i] + oY[j] * original.getWidth()];
                        a = (argb >>> 24);
                        if (a == 0) {
                            continue;
                        }
                        w = a * w;
                        outColorWeight += w;
                        r = (argb & 0x00ff0000) >>> 16;
                        g = (argb & 0x0000ff00) >>> 8;
                        b = argb & 0x000000ff;
                        outRed += w * r;
                        outGreen += w * g;
                        outBlue += w * b;
                    }
                }
                if (outColorWeight > 0) {
                    outAlpha = outColorWeight / outWeight;
                    outRed = outRed / outColorWeight;
                    outGreen = outGreen / outColorWeight;
                    outBlue = outBlue / outColorWeight;
                }
                rawOutput[newX + newY * newWidth] = (outAlpha << 24)
                        | (outRed << 16) | (outGreen << 8) | outBlue;
            }
        }
        return Image.createRGBImage(rawOutput, newWidth, newHeight, true);
    }
}

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