在 C# 中转换位图像素格式
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Converting Bitmap PixelFormats in C#
提问by Jono
I need to convert a Bitmap from PixelFormat.Format32bppRgbto PixelFormat.Format32bppArgb.
我需要一个位图从转换PixelFormat.Format32bppRgb到PixelFormat.Format32bppArgb。
I was hoping to use Bitmap.Clone, but it does not seem to be working.
我希望使用 Bitmap.Clone，但它似乎不起作用。
Bitmap orig = new Bitmap("orig.bmp");
Bitmap clone = orig.Clone(new Rectangle(0,0,orig.Width,orig.Height), PixelFormat.Format24bppArgb);
If I run the above code and then check clone.PixelFormat it is set to PixelFormat.Format32bppRgb. What is going on/how do I convert the format?
如果我运行上面的代码然后检查 clone.PixelFormat 它被设置为PixelFormat.Format32bppRgb. 发生了什么/如何转换格式？
采纳答案by Hans Passant
Sloppy, not uncommon for GDI+. This fixes it:
马虎，GDI+ 并不少见。这修复了它：
Bitmap orig = new Bitmap(@"c:\tempbpp.bmp");
Bitmap clone = new Bitmap(orig.Width, orig.Height,
System.Drawing.Imaging.PixelFormat.Format32bppPArgb);
using (Graphics gr = Graphics.FromImage(clone)) {
gr.DrawImage(orig, new Rectangle(0, 0, clone.Width, clone.Height));
}
// Dispose orig as necessary...
回答by Benjamin Podszun
using (var bmp = new Bitmap(width, height, PixelFormat.Format24bppArgb))
using (var g = Graphics.FromImage(bmp)) {
g.DrawImage(..);
}
Should work like that. Maybe you want to set some parameters on gto define the interpolation mode for quality etc.
应该这样工作。也许你想设置一些参数g来定义质量等的插值模式。
回答by Dan7
For some reason if you create a Bitmapfrom a file path, i.e. Bitmap bmp = new Bitmap("myimage.jpg");, and call Clone()on it, the returned Bitmapwill not be converted.
出于某种原因，如果您Bitmap从文件路径创建 aBitmap bmp = new Bitmap("myimage.jpg");并调用Clone()它，则返回的Bitmap将不会被转换。
However if you create another Bitmapfrom your old Bitmap, Clone()will work as intended.
但是，如果您Bitmap从旧的Bitmap. 中创建另一个，Clone()将按预期工作。
Try something like this:
尝试这样的事情：
using (Bitmap oldBmp = new Bitmap("myimage.jpg"))
using (Bitmap newBmp = new Bitmap(oldBmp))
using (Bitmap targetBmp = newBmp.Clone(new Rectangle(0, 0, newBmp.Width, newBmp.Height), PixelFormat.Format32bppArgb))
{
// targetBmp is now in the desired format.
}
