合并大型单色 (BW) 图像

Question

我需要处理大单色图像。我基本上需要向高分辨率（如 30000x20000 像素）单色图像（400dpi 的 A2+ 图）添加横幅（框架和格式化文本）。

默认的PixelFormat是Format1bppIndexed，这使得即使是大图也相对较小。但是，使用 .NET GDI+ Graphics 对象需要 unindexed 位图。

当将图像转换为可用的最低未索引时 PixelFormat.Format16bppGrayscale:

bmpResized = ImgResized.Clone(New System.Drawing.Rectangle(0, 0, ImgResized.Width, ImgResized.Height),
             System.Drawing.Imaging.PixelFormat.Format16bppGrayScale)

...它变得很大，无法由 Image 和 Bitmap 处理（OutOfMemoryExeption: Not enough memory - 在 32GB 机器上）。我尝试单独创建横幅并按像素连接图片，但是我运行遇到了完全相同的限制 - SetPixel 需要未索引的位图。

有什么办法可以克服这些问题吗？

编辑：一个可能的解决方案是创建一个字节数组并根据 [https://social.msdn.microsoft.com/Forums/vstudio/en-US/54a096ff-46f3-45ce-8560-bf5a0618ef75/how-to-set-pixel-into-bitmap-with-pixel-format-of-format8bppindexed-?forum=csharpgeneral][1] 编辑字节。但是我不确定我如何 "shift" 第二个图像字节。

Answer 1

最后我不得不使用位操作来完成它。效果很完美，连性能都很好

' Create byte array for the main ploted TIF image
Dim bmp As New Drawing.Bitmap(Img.Width, Img.Height, Drawing.Imaging.PixelFormat.Format1bppIndexed)
bmp = Img   ' getting bitmap from the default image
Dim data As System.Drawing.Imaging.BitmapData = bmp.LockBits(New Drawing.Rectangle(0, 0, bmp.Width, bmp.Height), Drawing.Imaging.ImageLockMode.[WriteOnly], Drawing.Imaging.PixelFormat.Format1bppIndexed)
Dim bytes As Byte() = New Byte(data.Height * data.Stride - 1) {}
System.Runtime.InteropServices.Marshal.Copy(data.Scan0, bytes, 0, bytes.Length)


' Create byte array for the banner
Dim bmpB As New Drawing.Bitmap(Img.Width, Img.Height, Drawing.Imaging.PixelFormat.Format1bppIndexed)
bmpB = Img.Clone()   ' banner had to be generated in 16bppp unindexed gray scale image to be able to use graphics
Dim dataB As System.Drawing.Imaging.BitmapData = bmpB.LockBits(New Drawing.Rectangle(0, 0, BmpB.Width, BmpB.Height), Drawing.Imaging.ImageLockMode.[WriteOnly], Drawing.Imaging.PixelFormat.Format1bppIndexed)
Dim bytesB As Byte() = New Byte(dataB.Height * dataB.Stride - 1) {}
System.Runtime.InteropServices.Marshal.Copy(dataB.Scan0, bytesB, 0, bytesB.Length)


' Join byte arrays:  Resulting bitmap = plotted TIF + banner
Dim bytesResult((bytes.Length + bytesB.Length) - 1) As Byte
bytesB.CopyTo(bytesResult, 0)
bytes.CopyTo(bytesResult, bytesB.Length)


' Revert resulting byte array back to bitmap and save resulting TIF image
BmpResized = New Bitmap(Img.Width, Img.Height * 2, Drawing.Imaging.PixelFormat.Format1bppIndexed)
Dim dataResult As System.Drawing.Imaging.BitmapData = BmpResized.LockBits(New Drawing.Rectangle(0, 0, BmpResized.Width, BmpResized.Height), Drawing.Imaging.ImageLockMode.[WriteOnly], Drawing.Imaging.PixelFormat.Format1bppIndexed)
System.Runtime.InteropServices.Marshal.Copy(bytesResult, 0, dataResult.Scan0, bytes.Length + bytesB.Length - 0)
Dim exportFileName As String = filenames1(0).Replace(".tif", "_mod.tif")
exportFileName = exportFileName.Replace(".png", "_mod.tif")
BmpResized.Save(exportFileName, Drawing.Imaging.ImageFormat.Tiff)

' Unlock locked bitmaps
bmp.UnlockBits(dataResult)
BmpResized.UnlockBits(dataResult)

' dispose anything not used later...

合并大型单色 (BW) 图像

Merge large monochromatic (BW) images

vb.net

graphics

monochrome

marshalling

pixelformat