BMP位图转换：24bpp转1bpp — Java实现

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基本概念

BPP：bits per pixel，每个像素的比特数。

场景

Java语言实现

package com.master.tools import android.graphics.Bitmap; import android.graphics.Color; import android.util.Log; import java.io.IOException; public class BmpConvert { 
    private BmpFileHeader fileHeader = new BmpFileHeader(); private BmpInfoHerder infoHeader = new BmpInfoHerder(); private RGBQUAD[] rgbQuadList = null; private byte[] data = null; public BmpConvert(Bitmap bitmap, short bitCount) throws IOException { 
    if (bitmap == null) { 
    return; } this.infoHeader.biSize = 40; this.infoHeader.biWidth = bitmap.getWidth(); this.infoHeader.biHeight = bitmap.getHeight(); this.infoHeader.biPlanes = 1; this.infoHeader.biBitCount = bitCount; this.infoHeader.biCompression = 0; this.infoHeader.biSizeImage = 0; this.infoHeader.bixPelsPerMeter = 0; this.infoHeader.biyPelsPerMeter = 0; this.infoHeader.biClrUsed = 0; this.infoHeader.biClrImportant = 0; if (this.infoHeader.biBitCount == 1) { 
    this.rgbQuadList = new RGBQUAD[2]; this.rgbQuadList[0] = new RGBQUAD(); this.rgbQuadList[0].rgbBlue = 0; this.rgbQuadList[0].rgbGreen = 0; this.rgbQuadList[0].rgbRed = 0; this.rgbQuadList[0].rgbRed = 0; this.rgbQuadList[1] = new RGBQUAD(); this.rgbQuadList[1].rgbBlue = -1; this.rgbQuadList[1].rgbGreen = -1; this.rgbQuadList[1].rgbRed = -1; this.rgbQuadList[1].rgbRed = 0; } else if (this.infoHeader.biBitCount == 4) { 
    this.rgbQuadList = new RGBQUAD[16]; } else if (this.infoHeader.biBitCount == 8) { 
    this.rgbQuadList = new RGBQUAD[256]; } int bmpWidth = ((this.infoHeader.biWidth + 7) / this.infoHeader.biBitCount / 8 + 3) / 4 * 4; int bufferSize = bmpWidth * this.infoHeader.biHeight; this.fileHeader.bfType = 19778; this.fileHeader.bfReserved1 = 0; this.fileHeader.bfReserved2 = 0; this.fileHeader.bfOffBits = (54 + this.rgbQuadList.length * 4); this.fileHeader.bfSize = (this.fileHeader.bfOffBits + bufferSize); this.infoHeader.biSizeImage = (this.fileHeader.bfSize - this.fileHeader.bfOffBits); this.data = new byte[this.fileHeader.bfSize]; int writeSize = 0; writeSize += writeWord(this.data, writeSize, this.fileHeader.bfType); writeSize += writeDword(this.data, writeSize, this.fileHeader.bfSize); writeSize = writeSize + writeWord(this.data, writeSize, this.fileHeader.bfReserved1); writeSize = writeSize + writeWord(this.data, writeSize, this.fileHeader.bfReserved2); writeSize += writeDword(this.data, writeSize, this.fileHeader.bfOffBits); writeSize += writeDword(this.data, writeSize, this.infoHeader.biSize); writeSize += writeLong(this.data, writeSize, this.infoHeader.biWidth); writeSize += writeLong(this.data, writeSize, this.infoHeader.biHeight); writeSize += writeWord(this.data, writeSize, this.infoHeader.biPlanes); writeSize += writeWord(this.data, writeSize, this.infoHeader.biBitCount); writeSize = writeSize + writeDword(this.data, writeSize, this.infoHeader.biCompression); writeSize = writeSize + writeDword(this.data, writeSize, this.infoHeader.biSizeImage); writeSize = writeSize + writeLong(this.data, writeSize, this.infoHeader.bixPelsPerMeter); writeSize = writeSize + writeLong(this.data, writeSize, this.infoHeader.biyPelsPerMeter); writeSize += writeDword(this.data, writeSize, this.infoHeader.biClrUsed); writeSize = writeSize + writeDword(this.data, writeSize, this.infoHeader.biClrImportant); for (int n = 0; n < this.rgbQuadList.length; n++) { 
    writeSize = writeSize + writeByte(this.data, writeSize, this.rgbQuadList[n].rgbBlue); writeSize = writeSize + writeByte(this.data, writeSize, this.rgbQuadList[n].rgbGreen); writeSize = writeSize + writeByte(this.data, writeSize, this.rgbQuadList[n].rgbRed); writeSize = writeSize + writeByte(this.data, writeSize, this.rgbQuadList[n].rgbReserved); } int[] pixels = new int[this.infoHeader.biWidth * this.infoHeader.biHeight]; bitmap.getPixels(pixels, 0, this.infoHeader.biWidth, 0, 0, this.infoHeader.biWidth, this.infoHeader.biHeight); int j = 0; int nRealCol = this.infoHeader.biHeight - 1; int blockSize = 8; int maxW = (this.infoHeader.biWidth + blockSize - 1) / blockSize; tick[1] = System.currentTimeMillis(); for (; j < this.infoHeader.biHeight; nRealCol--) { 
    int colStart = writeSize + nRealCol * bmpWidth; for (int wRow = 0; wRow < maxW; wRow++) { 
    int startNum = blockSize * wRow; for (int n = 0; (n < blockSize) && ( startNum + n < this.infoHeader.biWidth); n++) { 
    int clr = pixels[ (startNum + n + j * this.infoHeader.biWidth)]; int gray = getGreyLevel(clr, 1.0F); if (gray > 127) { 
    int cz = 1; int tmpIndex = colStart + wRow; byte[] tmpBytes = this.data; tmpBytes[tmpIndex] = ((byte)(tmpBytes[tmpIndex] + (byte)(cz << 7 - n))); } } } j++; } } public byte[] getData() { 
    return this.data; } public int getWidth() { 
    return this.infoHeader.biWidth; } public int getHeight() { 
    return this.infoHeader.biHeight; } public int getBitCount() { 
    return this.infoHeader.biBitCount; } private int writeWord(byte[] stream, int start, int value) throws IOException { 
    byte[] b = new byte[2]; b[0] = ((byte)(value & 0xFF)); b[1] = ((byte)(value >> 8 & 0xFF)); System.arraycopy(b, 0, stream, start, 2); return 2; } private int writeDword(byte[] stream, int start, long value) throws IOException { 
    byte[] b = new byte[4]; b[0] = ((byte)(int)(value & 0xFF)); b[1] = ((byte)(int)(value >> 8 & 0xFF)); b[2] = ((byte)(int)(value >> 16 & 0xFF)); b[3] = ((byte)(int)(value >> 24 & 0xFF)); System.arraycopy(b, 0, stream, start, 4); return 4; } private int writeLong(byte[] stream, int start, long value) throws IOException { 
    byte[] b = new byte[4]; b[0] = ((byte)(int)(value & 0xFF)); b[1] = ((byte)(int)(value >> 8 & 0xFF)); b[2] = ((byte)(int)(value >> 16 & 0xFF)); b[3] = ((byte)(int)(value >> 24 & 0xFF)); System.arraycopy(b, 0, stream, start, 4); return 4; } private int writeByte(byte[] stream, int start, byte value) throws IOException { 
    stream[start] = value; return 1; } public static int getGreyLevel(int pixel, float intensity) { 
    float alpha = Color.alpha(pixel); if (alpha < 50.0F) { 
    return 255; } float red = Color.red(pixel); float green = Color.green(pixel); float blue = Color.blue(pixel); float parcial = red + green + blue; parcial = (float)(parcial / 3.0D); int gray = (int)(parcial * intensity); if (gray > 255) { 
    gray = 255; } return gray; } public class BmpFileHeader { 
    public short bfType; public int bfSize; public short bfReserved1; public short bfReserved2; public int bfOffBits; public BmpFileHeader() { 
    } } public class BmpInfoHerder { 
    public short biSize; public int biWidth; public int biHeight; public short biPlanes; public short biBitCount; public int biCompression; public int biSizeImage; public int bixPelsPerMeter; public int biyPelsPerMeter; public int biClrUsed; public int biClrImportant; public BmpInfoHerder() { 
    } } public class RGBQUAD { 
    public byte rgbBlue; public byte rgbGreen; public byte rgbRed; public byte rgbReserved; public RGBQUAD() { 
    } } } 

使用示例
BmpConvert bmpConvert = new BmpConvert(srcBtimap, (short)1);
byte[] bmpData = bmpConvert.getData();

bmpData为转换后像素深度为1的BMP位图数据，写入文件即可。