我想读取灰度图像文件,例如lena.bmp,然后降低java中的灰度级分辨率,我使用PixelGrabber
来获取此图像的像素数据,如何转换此8位灰度位图到4位?
谢谢!
答案 0 :(得分:2)
如果他们可以在这里帮助你,那就不舒服了,但也许你可以看看JAI (Java Advanced Imaging),Apache Commons Sanselan或Image4j。
刚刚测试了Image4J库:
转换8位 - > 4位非常简单:
final File inFile = new File("test.bmp");
final File outFile = new File("test2.bmp");
BufferedImage inImage = ImageIO.read(inFile);
BufferedImage outImage = ConvertUtil.convert4(inImage); // Converts to 4 Bit
ImageIO.write(outImage, "bmp", outFile);
有关更多信息,请参阅Image4J - ConvertUtil Documentation。
答案 1 :(得分:1)
这确实将位数减少到4:
public static void main(String[] args) throws Exception {
BufferedImage in = ImageIO.read(new File(args[0]));
int w = in.getWidth(), h = in.getHeight();
int[] bits = { 4 };
ColorSpace cs = ColorSpace.getInstance(ColorSpace.CS_GRAY);
int dt = DataBuffer.TYPE_BYTE;
ColorModel cm = new ComponentColorModel
(cs, bits, false, false, Transparency.OPAQUE, dt);
WritableRaster wr = cm.createCompatibleWritableRaster(w, h);
BufferedImage out = new BufferedImage(cm, wr, false, null);
Graphics2D g = out.createGraphics();
g.drawImage(in, 0, 0, null);
g.dispose();
ImageIO.write(out, "png", new File(args[1]));
}
到目前为止,我尝试过的所有查看器应用程序的结果文件看起来都太暗了。但如果您只对这些位感兴趣,那么在上述转换之后对wr
栅格进行操作可能就足够了。
如果没有,那么也许您应该设置一个IndexedColorModel
,其中包含您想要的2 4 灰度级。您可以简单地将索引乘以17,以获得从0x0 * 17 = 0x00
到0xf * 17 = 0xff
的均匀间隔的强度。
public static void main(String[] args) throws Exception {
BufferedImage in = ImageIO.read(new File(args[0]));
int w = in.getWidth(), h = in.getHeight();
byte[] v = new byte[1 << 4];
for (int i = 0; i < v.length; ++i)
v[i] = (byte)(i*17);
ColorModel cm = new IndexColorModel(4, v.length, v, v, v);
WritableRaster wr = cm.createCompatibleWritableRaster(w, h);
BufferedImage out = new BufferedImage(cm, wr, false, null);
Graphics2D g = out.createGraphics();
g.drawImage(in, 0, 0, null);
g.dispose();
ImageIO.write(out, "png", new File(args[1]));
}