合并大型单色 (BW) 图像

Question

我需要处理大型单色图像。我基本上需要将横幅(框架和格式化文本)添加到高分辨率(如 30000x20000 像素)单色图像(2 dpi的 A2+ 绘图)中。

默认PixelFormat是Format1bppIndexed，这使得即使是那些大图片的尺寸也相对较小。但是，使用 .NET GDI+Graphics对象需要未编制索引的位图。

将图像转换为最低的可用未索引PixelFormat.Format16bppGrayscale时：

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

。它变得很大，可以由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，但是我遇到了相同的限制 -SetPixel需要未索引的位图。

有没有办法克服这些问题？

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

Answer 1

最后，我不得不使用逐位操作来做到这一点。效果很好，甚至性能也非常好。

' 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...