我试图从pdf中提取图像。图像是过滤器“FlateDecode”。我得到的图像,但它只是一个黑色的道路。我是一个新手,请帮助我。该代码是:使用PdfSharp从pdf中提取“FLATEDECODE”类型的图像
int width = xObject.Elements.GetInteger(PdfImage.Keys.Width);
int height = xObject.Elements.GetInteger(PdfImage.Keys.Height);
int bitsPerComponent = xObject.Elements.GetInteger (PdfSharp.Pdf.Advanced.PdfImage.Keys.BitsPerComponent);
System.Drawing.Imaging.PixelFormat pixelFormat = new System.Drawing.Imaging.PixelFormat();
switch (bitsPerComponent)
{
case 1:
pixelFormat = System.Drawing.Imaging.PixelFormat.Format1bppIndexed;
break;
case 8:
pixelFormat = System.Drawing.Imaging.PixelFormat.Format8bppIndexed;
break;
case 24:
pixelFormat = System.Drawing.Imaging.PixelFormat.Format24bppRgb;
break;
default:
throw new Exception("Unknown pixel format " + bitsPerComponent);
}
Bitmap bitmap = new Bitmap(width, height, pixelFormat);
byte[] raw = xObject.Stream.Value;
BitmapData bitmapData = bitmap.LockBits(new Rectangle(0, 0, width, height), ImageLockMode.WriteOnly, pixelFormat);
Marshal.Copy(raw, 0, bitmapData.Scan0, raw.Length);
bitmap.UnlockBits(bitmapData);
using (MemoryStream imageStream = new MemoryStream())
{
bitmap.Save(imageStream, ImageFormat.png);
System.Drawing.Image img = System.Drawing.Image.FromStream(imageStream);
img.Save("D:\\trial.png", System.Drawing.Imaging.ImageFormat.png);
}
请注意,索引图像由位和调色板 - 你抽取位,但不是调色板(如果你开始和24bpp图像没有问题)。 PDF中的位是字节对齐的,而Windows位图中的位是DWORD对齐的;一旦你解决了黑色补丁问题,你可能会看到不同之处。 –
谢谢PDFsharp团队...但我不知道如何提取颜色调色板。你能帮我解决这个问题吗...... – Mugdha