Bad text rendering using DrawString on top of transparent pixels

The first output is what you get when you draw black text on a black background, probably Color.Transparent. The 2nd was drawn on an almost-black background. The 3rd was drawn on the same background it is being displayed with.

Anti-aliasing cannot work when on a transparent background. The colors used for the anti-aliasing pixels will not blend the letter shape into the background when the text is displayed with a different background. Those pixels will now become very noticeable and make the text look very bad.

Note that SmoothingMode doesn't affect text output. It will look slightly less bad if you use a lower quality TextRenderingHint and a background color that's grayish with a alpha of zero. Only TextRenderingHint.SingleBitPerPixelGridFit avoids all anti-aliasing troubles.

Getting a perfect fix for this is very difficult. Vista's glass effect on the window title bar uses very subtle shading to give the text a well defined background color. You'd need SysInternals' ZoomIt tool to really see it. DrawThemeTextEx() function with a non-zero iGlowSize.

There is a very simple answer to this...

g.TextRenderingHint = Drawing.Text.TextRenderingHint.AntiAliasGridFit

If you set this before you render your text, it will come out clear. In addition, this methods supports more font sizes (The default only goes up to size 56).

Thanks for reading this post.

The option I used to workaround this problem was:

Graphics graphics = new Graphics();
graphics.TextRenderingHint = System.Drawing.Text.TextRenderingHint.SingleBitPerPixelGridFit;

There are some others useful options in TextRenderingHint

Hope it helps