注意：再次提供我之前问题的背景，以便在一个来源找到所有相关内容。
我正在从Android移动设备捕获图像，它是JPEG格式的。图像为72X72DPI和24位。当我尝试使用LibTiff.Net将此JPEG图像转换为TIFF并为MinIsWhite设置标签Photometric Interpretation = 0时，图像变为负值（白色变为黑色，黑色变为白色）。环境是Windows 8.1 64位，Visual Studio 2012.标记必须具有值0，其中0 =白色为零。
我绝对必须在图像中使用Photometric.MINISWHITE，所以尝试在将图像数据写入TIFF之前将其反转，如下面的代码所示。但随后压缩变为LZW而不是CCITT4，Photometric从MINISWHITE更改为MINISBLACK，FIllorder标记被删除，PlanarConfig标记被删除，新标记Predictor添加值1，图像再次变为负值。
public partial class Form1 : Form
{
private const TiffTag TIFFTAG_ASCIITAG = (TiffTag)666;
private const TiffTag TIFFTAG_LONGTAG = (TiffTag)667;
private const TiffTag TIFFTAG_SHORTTAG = (TiffTag)668;
private const TiffTag TIFFTAG_RATIONALTAG = (TiffTag)669;
private const TiffTag TIFFTAG_FLOATTAG = (TiffTag)670;
private const TiffTag TIFFTAG_DOUBLETAG = (TiffTag)671;
private const TiffTag TIFFTAG_BYTETAG = (TiffTag)672;
public Form1()
{
InitializeComponent();
}
private void button1_Click(object sender, EventArgs e)
{
using (Bitmap bmp = new Bitmap(@"D:\Projects\ITests\images\IMG_2.jpg"))
{
// convert jpg image to tiff
byte[] tiffBytes = GetTiffImageBytes(bmp, false);
File.WriteAllBytes(@"D:\Projects\ITests\images\output.tif", tiffBytes);
//Invert the tiff image
Bitmap bmpTiff = new Bitmap(@"D:\Projects\ITests\images\output.tif");
Bitmap FBitmap = Transform(bmpTiff);
FBitmap.Save(@"D:\Projects\ITests\images\invOutput1.tif");
}
}
public static byte[] GetTiffImageBytes(Bitmap img, bool byScanlines)
{
try
{
byte[] raster = GetImageRasterBytes(img);
using (MemoryStream ms = new MemoryStream())
{
using (Tiff tif = Tiff.ClientOpen("InMemory", "w", ms, new TiffStream()))
{
if (tif == null)
return null;
tif.SetField(TiffTag.IMAGEWIDTH, img.Width);
tif.SetField(TiffTag.IMAGELENGTH, img.Height);
tif.SetField(TiffTag.COMPRESSION, Compression.CCITTFAX4);
tif.SetField(TiffTag.PHOTOMETRIC, Photometric.MINISWHITE);
tif.SetField(TiffTag.ROWSPERSTRIP, img.Height);
tif.SetField(TiffTag.XRESOLUTION, 200);
tif.SetField(TiffTag.YRESOLUTION, 200);
tif.SetField(TiffTag.SUBFILETYPE, 0);
tif.SetField(TiffTag.BITSPERSAMPLE, 1);
tif.SetField(TiffTag.FILLORDER, FillOrder.LSB2MSB);
tif.SetField(TiffTag.ORIENTATION, BitMiracle.LibTiff.Classic.Orientation.TOPLEFT);
tif.SetField(TiffTag.SAMPLESPERPIXEL, 1);
tif.SetField(TiffTag.RESOLUTIONUNIT, ResUnit.INCH);
tif.SetField(TiffTag.PLANARCONFIG, PlanarConfig.CONTIG);
int tiffStride = tif.ScanlineSize();
int stride = raster.Length / img.Height;
if (byScanlines)
{
// raster stride MAY be bigger than TIFF stride (due to padding in raster bits)
for (int i = 0, offset = 0; i < img.Height; i++)
{
bool res = tif.WriteScanline(raster, offset, i, 0);
if (!res)
return null;
offset += stride;
}
}
else
{
if (tiffStride < stride)
{
// raster stride is bigger than TIFF stride
// this is due to padding in raster bits
// we need to create correct TIFF strip and write it into TIFF
byte[] stripBits = new byte[tiffStride * img.Height];
for (int i = 0, rasterPos = 0, stripPos = 0; i < img.Height; i++)
{
System.Buffer.BlockCopy(raster, rasterPos, stripBits, stripPos, tiffStride);
rasterPos += stride;
stripPos += tiffStride;
}
// Write the information to the file
int n = tif.WriteEncodedStrip(0, stripBits, stripBits.Length);
if (n <= 0)
return null;
}
else
{
// Write the information to the file
int n = tif.WriteEncodedStrip(0, raster, raster.Length);
if (n <= 0)
return null;
}
}
}
return ms.GetBuffer();
}
}
catch (Exception)
{
return null;
}
}
public static byte[] GetImageRasterBytes(Bitmap img)
{
// Specify full image
Rectangle rect = new Rectangle(0, 0, img.Width, img.Height);
Bitmap bmp = img;
byte[] bits = null;
try
{
// Lock the managed memory
if (img.PixelFormat != PixelFormat.Format1bppIndexed)
bmp = convertToBitonal(img);
BitmapData bmpdata = bmp.LockBits(rect, ImageLockMode.ReadOnly, PixelFormat.Format1bppIndexed);
// Declare an array to hold the bytes of the bitmap.
bits = new byte[bmpdata.Stride * bmpdata.Height];
// Copy the sample values into the array.
Marshal.Copy(bmpdata.Scan0, bits, 0, bits.Length);
// Release managed memory
bmp.UnlockBits(bmpdata);
}
finally
{
if (bmp != img)
bmp.Dispose();
}
return bits;
}
private static Bitmap convertToBitonal(Bitmap original)
{
int sourceStride;
byte[] sourceBuffer = extractBytes(original, out sourceStride);
// Create destination bitmap
Bitmap destination = new Bitmap(original.Width, original.Height,
PixelFormat.Format1bppIndexed);
destination.SetResolution(original.HorizontalResolution, original.VerticalResolution);
// Lock destination bitmap in memory
BitmapData destinationData = destination.LockBits(
new Rectangle(0, 0, destination.Width, destination.Height),
ImageLockMode.WriteOnly, PixelFormat.Format1bppIndexed);
// Create buffer for destination bitmap bits
int imageSize = destinationData.Stride * destinationData.Height;
byte[] destinationBuffer = new byte[imageSize];
int sourceIndex = 0;
int destinationIndex = 0;
int pixelTotal = 0;
byte destinationValue = 0;
int pixelValue = 128;
int height = destination.Height;
int width = destination.Width;
int threshold = 500;
for (int y = 0; y < height; y++)
{
sourceIndex = y * sourceStride;
destinationIndex = y * destinationData.Stride;
destinationValue = 0;
pixelValue = 128;
for (int x = 0; x < width; x++)
{
// Compute pixel brightness (i.e. total of Red, Green, and Blue values)
pixelTotal = sourceBuffer[sourceIndex + 1] + sourceBuffer[sourceIndex + 2] +
sourceBuffer[sourceIndex + 3];
if (pixelTotal > threshold)
destinationValue += (byte)pixelValue;
if (pixelValue == 1)
{
destinationBuffer[destinationIndex] = destinationValue;
destinationIndex++;
destinationValue = 0;
pixelValue = 128;
}
else
{
pixelValue >>= 1;
}
sourceIndex += 4;
}
if (pixelValue != 128)
destinationBuffer[destinationIndex] = destinationValue;
}
Marshal.Copy(destinationBuffer, 0, destinationData.Scan0, imageSize);
destination.UnlockBits(destinationData);
return destination;
}
private static byte[] extractBytes(Bitmap original, out int stride)
{
Bitmap source = null;
try
{
// If original bitmap is not already in 32 BPP, ARGB format, then convert
if (original.PixelFormat != PixelFormat.Format32bppArgb)
{
source = new Bitmap(original.Width, original.Height, PixelFormat.Format32bppArgb);
source.SetResolution(original.HorizontalResolution, original.VerticalResolution);
using (Graphics g = Graphics.FromImage(source))
{
g.DrawImageUnscaled(original, 0, 0);
}
}
else
{
source = original;
}
// Lock source bitmap in memory
BitmapData sourceData = source.LockBits(
new Rectangle(0, 0, source.Width, source.Height),
ImageLockMode.ReadOnly, PixelFormat.Format32bppArgb);
// Copy image data to binary array
int imageSize = sourceData.Stride * sourceData.Height;
byte[] sourceBuffer = new byte[imageSize];
Marshal.Copy(sourceData.Scan0, sourceBuffer, 0, imageSize);
// Unlock source bitmap
source.UnlockBits(sourceData);
stride = sourceData.Stride;
return sourceBuffer;
}
finally
{
if (source != original)
source.Dispose();
}
}
public Bitmap Transform(Bitmap bitmapImage)
{
var bitmapRead = bitmapImage.LockBits(new Rectangle(0, 0, bitmapImage.Width, bitmapImage.Height), ImageLockMode.ReadOnly, PixelFormat.Format32bppPArgb);
var bitmapLength = bitmapRead.Stride * bitmapRead.Height;
var bitmapBGRA = new byte[bitmapLength];
Marshal.Copy(bitmapRead.Scan0, bitmapBGRA, 0, bitmapLength);
bitmapImage.UnlockBits(bitmapRead);
for (int i = 0; i < bitmapLength; i += 4)
{
bitmapBGRA[i] = (byte)(255 - bitmapBGRA[i]);
bitmapBGRA[i + 1] = (byte)(255 - bitmapBGRA[i + 1]);
bitmapBGRA[i + 2] = (byte)(255 - bitmapBGRA[i + 2]);
// [i + 3] = ALPHA.
}
var bitmapWrite = bitmapImage.LockBits(new Rectangle(0, 0, bitmapImage.Width, bitmapImage.Height), ImageLockMode.WriteOnly, PixelFormat.Format32bppPArgb);
Marshal.Copy(bitmapBGRA, 0, bitmapWrite.Scan0, bitmapLength);
bitmapImage.UnlockBits(bitmapWrite);
return bitmapImage;
}
}
答案 0 :(得分：0)
在将它们写入TIFF之前，您应该在GetTiffImageBytes方法中反转图像字节。此外，Transform方法将双级图像转换为32bpp，这就是最终获得LZW压缩图像的原因。
所以，添加以下代码
for (int k = 0; k < raster.Length; k++)
raster[k] = (byte)(~raster[k]);
byte[] raster = GetImageRasterBytes(img);方法中GetTiffImageBytes之后。这将反转图像字节。并且不要使用以下代码
//Invert the tiff image
Bitmap bmpTiff = new Bitmap(@"D:\Projects\ITests\images\output.tif");
Bitmap FBitmap = Transform(bmpTiff);
FBitmap.Save(@"D:\Projects\ITests\images\invOutput1.tif");