使用 Bitmiracle Libtiff.net 创建 Bigtiff (>4GB) 文件

问题描述

首先我要感谢 Bitmiracle 提供了这个伟大的库.即使在创建非常大的文件时，内存占用也非常低.几天前，我遇到了一个问题，我想创建一个大于 4GB 的 tiff 文件.我成功创建了平铺 tiff 文件，但似乎创建超过 4GB 的平铺的颜色以某种方式反转.

First I want to thank Bitmiracle for this great lib. Even while creating very big files, the memory footprint is very low.A few days ago I ran into a problem where I wanted to create a tiff file bigger than 4GB. I created the tiled tiff file successfully, but it seems that the color of the tiles created beyond 4GB are somehow inverted.

这里代码相关代码:

用法:

WriteTiledTiff("bigtiff.tiff",BitmapSourceFromBrush(new RadialGradientBrush(Colors.Aqua,Colors.Red), 256));

方法:

public static BitmapSource BitmapSourceFromBrush(Brush drawingBrush, int size = 32, int dpi = 96)
    {
        // RenderTargetBitmap = builds a bitmap rendering of a visual
        var pixelFormat = PixelFormats.Pbgra32;
        RenderTargetBitmap rtb = new RenderTargetBitmap(size, size, dpi, dpi, pixelFormat);

        // Drawing visual allows us to compose graphic drawing parts into a visual to render
        var drawingVisual = new DrawingVisual();
        using (DrawingContext context = drawingVisual.RenderOpen())
        {
            // Declaring drawing a rectangle using the input brush to fill up the visual
            context.DrawRectangle(drawingBrush, null, new Rect(0, 0, size, size));
        }

        // Actually rendering the bitmap
        rtb.Render(drawingVisual);
        return rtb;
    }

public static void WriteTiledTiff(string fileName, BitmapSource tile)
    {
        const int PIXEL_WIDTH = 48000;
        const int PIXEL_HEIGHT = 48000;

         int iTile_Width = tile.PixelWidth;
         int iTile_Height = tile.PixelHeight;

        using (Tiff tiff = Tiff.Open(fileName, "w"))
        {
            tiff.SetField(TiffTag.IMAGEWIDTH, PIXEL_WIDTH);
            tiff.SetField(TiffTag.IMAGELENGTH, PIXEL_HEIGHT);
            tiff.SetField(TiffTag.COMPRESSION, Compression.NONE);
            tiff.SetField(TiffTag.PHOTOMETRIC, Photometric.RGB);

            tiff.SetField(TiffTag.ROWSPERSTRIP, PIXEL_HEIGHT);

            tiff.SetField(TiffTag.XRESOLUTION, 96);
            tiff.SetField(TiffTag.YRESOLUTION, 96);

            tiff.SetField(TiffTag.BITSPERSAMPLE, 8);
            tiff.SetField(TiffTag.SAMPLESPERPIXEL, 3);

            tiff.SetField(TiffTag.PLANARCONFIG, PlanarConfig.CONTIG);

            tiff.SetField(TiffTag.TILEWIDTH, iTile_Width);
            tiff.SetField(TiffTag.TILELENGTH, iTile_Height);

            int tileC = 0;
            for (int row = 0; row < PIXEL_HEIGHT; row += iTile_Height)
            {
                for (int col = 0; col < PIXEL_WIDTH; col += iTile_Width)
                {
                    if (tile.Format != PixelFormats.Rgb24) tile = new FormatConvertedBitmap(tile, PixelFormats.Rgb24, null, 0);
                    int stride = tile.PixelWidth * ((tile.Format.BitsPerPixel + 7) / 8);

                    byte[] pixels = new byte[tile.PixelHeight * stride];
                    tile.CopyPixels(pixels, stride, 0);

                    tiff.WriteEncodedTile(tileC++, pixels, pixels.Length);
                }
            }

            tiff.WriteDirectory();
        }
    }

生成的文件大小为 6.47GB.我用一个叫做vliv"的小工具查看了它vilv下载

The resulted file will be 6,47GB in size. I viewed it with a small tool called "vliv" vilv download

推荐答案

包括 2.4.500.0 在内的所有 LibTiff.Net 版本都基于原始 libtiff 的 3.x 分支.

All LibTiff.Net versions including 2.4.500.0 are based on 3.x branch of the original libtiff.

在原始 libtiff 的 4.x 分支中引入了对 BigTIFF 的支持.因此，目前没有 LibTiff.Net 版本旨在处理磁盘上超过 4GB 的 BigTiff 文件/文件.

Support for BigTIFF was introduced in 4.x branch of the original libtiff. Thus, at this time there are no LibTiff.Net versions designed to handle BigTiff files / files over 4GB on disk.

LibTiff.Net 2.4.508 添加了对 BigTiff 的支持.

LibTiff.Net 2.4.508 adds support for BigTiff.

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