题
有没有人知道一种平滑/快速的方式来消除透明度,例如pngs / tiffs等用白色背景替换它?
基本上我需要的是我需要创建PDF / A兼容图像,根据规范,它可能具有-no-透明度(因此固定的白色背景很好)。
有任何想法/建议吗?
干杯&谢谢, -Jö RG
解决方案
你可以创建一个与png大小相同的位图,绘制一个白色矩形,然后在它上面绘制图像。
void RemTransp(string file) {
Bitmap src = new Bitmap(file);
Bitmap target = new Bitmap(src.Size.Width,src.Size.Height);
Graphics g = Graphics.FromImage(target);
g.DrawRectangle(new Pen(new SolidBrush(Color.White)), 0, 0, target.Width, target.Height);
g.DrawImage(src, 0, 0);
target.Save("Your target path");
}
其他提示
您必须删除Alpha通道。否则你仍然会有一个透明的图像 - 只是没有透明区域。
class Program
{
static void Main(string[] args)
{
//this also works for different file formats
ReplaceTransparency(@"C:\Y\transparent.png", System.Drawing.Color.White).Save(@"C:\Y\no_transparency.png");
ReplaceTransparency(@"C:\Y\transparent.gif", System.Drawing.Color.White).Save(@"C:\Y\no_transparency.gif");
}
public static System.Drawing.Bitmap ReplaceTransparency(string file, System.Drawing.Color background)
{
return ReplaceTransparency(System.Drawing.Image.FromFile(file), background);
}
public static System.Drawing.Bitmap ReplaceTransparency(System.Drawing.Image image, System.Drawing.Color background)
{
return ReplaceTransparency((System.Drawing.Bitmap)image, background);
}
public static System.Drawing.Bitmap ReplaceTransparency(System.Drawing.Bitmap bitmap, System.Drawing.Color background)
{
/* Important: you have to set the PixelFormat to remove the alpha channel.
* Otherwise you'll still have a transparent image - just without transparent areas */
var result = new System.Drawing.Bitmap(bitmap.Size.Width, bitmap.Size.Height, System.Drawing.Imaging.PixelFormat.Format24bppRgb);
var g = System.Drawing.Graphics.FromImage(result);
g.Clear(background);
g.CompositingMode = System.Drawing.Drawing2D.CompositingMode.SourceOver;
g.DrawImage(bitmap, 0, 0);
return result;
}
}
1)创建一个白色背景且尺寸与图像相同的位图 2)加载你的图像并将其绘制在你的“白色”之上。位图结果 3)保存新创建的图像
PNG具有alpha通道,因此简单的重新着色不会。创建相同大小的白色图像,并创建合成图像覆盖图像。
添加到Stormenet的答案;记得用“使用”包装所有的Bitmap和Graphics对象处置非托管资源的声明。
名称空间:
using Microsoft.Win32;
using System.Windows.Media;
using System.Windows.Media.Imaging;
using PdfSharp;
using PdfSharp.Pdf;
using PdfSharp.Drawing;
从File:
创建PNG或TIFF BitmapSourceBitmapSource BitmapSource;
private void OpenFile(Object sender, RoutedEventArgs e)
{
OpenFileDialog OpenFileDialog = new OpenFileDialog();
OpenFileDialog.Filter = "PNG files (*.png)|*.png|TIFF files (*.tif)|*.tif";
if (OpenFileDialog.ShowDialog() == true)
{
try
{
if (OpenFileDialog.OpenFile() != null)
{
String InitialPath = OpenFileDialog.FileName;
FileStream InitialFileStream = new FileStream(InitialPath, FileMode.Open, FileAccess.Read, FileShare.Read);
switch (OpenFileDialog.FilterIndex)
{
case 1:
PngBitmapDecoder PngBitmapDecoder = new PngBitmapDecoder(InitialFileStream, BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.OnLoad);
BitmapSource = PngBitmapDecoder.Frames[0];
InitialFileStream.Close();
break;
case 2:
TiffBitmapDecoder TiffBitmapDecoder = new TiffBitmapDecoder(InitialFileStream, BitmapCreateOptions.PreservePixelFormat, BitmapCacheOption.OnLoad);
BitmapSource = TiffBitmapDecoder.Frames[0];
InitialFileStream.Close();
break;
}
}
}
catch (Exception Exception)
{
MessageBox.Show("Error: Could not read file from disk. Original error: ", Exception.Message, MessageBoxButton.OK, MessageBoxImage.Error);
}
}
}
按钮上的功能点击:
private void ButtonClick(Object sender, RoutedEventArgs e)
{
PixelFormat PixelFormat = BitmapSource.Format;
if (PixelFormat == PixelFormats.Bgra32)
{
try
{
BitmapSource = Bgra32ToBgra24(BitmapSource);
//BitmapSource = Bgra32ToGray8(BitmapSource);
}
catch (Exception Exception)
{
MessageBox.Show("Error: Could not convert BitmapSource. Original error: ", Exception.Message, MessageBoxButton.OK, MessageBoxImage.Error);
}
}
}
功能:
public static BitmapSource Bgra32ToBgr24(BitmapSource BitmapSource)
{
Int32 PixelWidth = BitmapSource.PixelWidth;
Int32 PixelHeight = BitmapSource.PixelHeight;
Double DpiX = BitmapSource.DpiX;
Double DpiY = BitmapSource.DpiY;
PixelFormat InputPixelFormat = BitmapSource.Format;
BitmapPalette InputPalette = BitmapSource.Palette;
Int32 InputBitsPerPixel = BitmapSource.Format.BitsPerPixel;
Int32 InputStride = PixelWidth * InputBitsPerPixel / 8;
Byte[] InputPixelsArray = new Byte[InputStride * PixelHeight];
BitmapSource.CopyPixels(InputPixelsArray, InputStride, 0);
PixelFormat PixelFormat = PixelFormats.Bgr24;
BitmapPalette Palette = null;
Int32 BitsPerPixel = 24;
Int32 Stride = PixelWidth * BitsPerPixel / 8;
Byte[] PixelsArray = new Byte[InputStride * PixelHeight / 4 * 3];
Int32 i = 0; Int32 j = 0; Int32 k = 0;
while (i < InputPixelsArray.Length / 4)
{
PixelsArray[k] = InputPixelsArray[j];
PixelsArray[k + 1] = InputPixelsArray[j + 1];
PixelsArray[k + 2] = InputPixelsArray[j + 2];
i = i + 1;
j = j + 4;
k = k + 3;
}
BitmapSource = BitmapSource.Create(PixelWidth, PixelHeight, DpiX, DpiY, PixelFormat, Palette, PixelsArray, Stride);
return BitmapSource;
}
将频道转换为Gray8 BitmapSource
public static BitmapSource Bgra32ToGray8(BitmapSource BitmapSource)
{
Int32 PixelWidth = BitmapSource.PixelWidth;
Int32 PixelHeight = BitmapSource.PixelHeight;
Double DpiX = BitmapSource.DpiX;
Double DpiY = BitmapSource.DpiY;
PixelFormat InputPixelFormat = BitmapSource.Format;
BitmapPalette InputPalette = BitmapSource.Palette;
Int32 InputBitsPerPixel = BitmapSource.Format.BitsPerPixel;
Int32 InputStride = PixelWidth * InputBitsPerPixel / 8;
Byte[] InputPixelsArray = new Byte[InputStride * PixelHeight];
BitmapSource.CopyPixels(InputPixelsArray, InputStride, 0);
PixelFormat PixelFormat = PixelFormats.Gray8;
BitmapPalette Palette = null;
Int32 BitsPerPixel = 8;
Int32 Stride = PixelWidth * BitsPerPixel / 8;
Byte[] A_PixelsArray = new Byte[InputStride * PixelHeight / 4];
Int32 i = 0; Int32 j = 3;
while (i < InputPixelsArray.Length / 4)
{
A_PixelsArray[i] = InputPixelsArray[j];
i = i + 1;
j = j + 4;
}
BitmapSource = BitmapSource.Create(PixelWidth, PixelHeight, DpiX, DpiY, PixelFormat, Palette, A_PixelsArray, Stride);
return BitmapSource;
}
将BitmapSource保存为PDF:
private void SaveFileAs(Object sender, RoutedEventArgs e)
{
SaveFileDialog SaveFileDialog = new SaveFileDialog();
SaveFileDialog.Filter = "PDF files (*.pdf)|*.pdf";
if (SaveFileDialog.ShowDialog() == true)
{
try
{
if (SaveFileDialog.FileName != null)
{
String DestinationPath = SaveFileDialog.FileName;
FileStream DestinationFileStream = new FileStream(DestinationPath, FileMode.Create, FileAccess.Write, FileShare.Write);
switch (SaveFileDialog.FilterIndex)
{
case 1:
PdfDocument PdfDocument = new PdfDocument();
PdfPage PdfPage = new PdfPage();
PdfDocument.Pages.Add(PdfPage);
XImage Image = XImage.FromBitmapSource(BitmapSource);
XGraphics XGraphic = XGraphics.FromPdfPage(PdfDocument.Pages[0]);
Double VerticalMargin = 20;
Double HorizontalMargin = 20;
Double Ratio = BitmapSource.Height / BitmapSource.Width;
Double ImageWidth = PdfPage.Width - 2 * VerticalMargin;
Double ImageHeight = Ratio * (PdfPage.Width - 2 * HorizontalMargin);
XGraphic.DrawImage(Image, VerticalMargin, HorizontalMargin, ImageWidth, ImageHeight);
PdfDocument.Save(DestinationFileStream);
PdfDocument.Close();
DestinationFileStream.Close();
break;
}
}
}
catch (Exception Exception)
{
MessageBox.Show("Error: Could not write file to disk. Original error: ", Exception.Message, MessageBoxButton.OK, MessageBoxImage.Error);
}
}
}
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