Graphics (Text) Quality in an VRM9 Overlay Bitmap

I am developing an Win32 application that superimposes text over fullscreen video using VMR9AlphaBitmap. One thing I've noticed is that the graphics quality seems to be worse when displaying the bitmap with video than when it is created and displayed on a normal window. In particular, the edges of the characters are jagged, not smooth.

Also, I create shadows and other effects for the text by offsetting by one or more pixels and redrawing, using the system colors COLOR_3DSHADOW, COLOR_3DDKSHADOW, and COLOR_3DLIGHT. This works great on a normal window, but when I do this over video, some of the yellow (the color used for the source key) bleeds through.

Can someone explain to me why I am seeing this and how I can workaround these issues

Thanks...

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Graphics (Text) Quality in an VRM9 Overlay Bitmap

FlashyPants
Did you finish this application
ITJoeB
It sounds like you may be using anti-aliasing or cleartype when drawing the text. When drawing on a solid background color this works well. However with video always changing the aliased pixels may appear as garbage around the character. You may want to try changing the background color used for the bitmap to black (if it is not). This may help with aliasing, otherwise turn off aliasing and see what you get.
monchhib

What is your color key value It may work better with a darker color. It does not matter which function draws the text as anti-aliasing is done in much the same way. Standard is single color and cleartype uses multiple shades. Ultimately it needs to be an alpha overlay where the color key is the video and everything else in the bitmap should be alpha blended. With a quick look I did not see any documentation on how to do it this way.
yamobe
Your description points to anti-aliasing even more. Bleed through of a color key can occur due to anti-aliasing where the background color is used as a reference to blend the edges of the character. This secondary color will be slightly different to the background color and appear as a bleed through. Perhaps on the alternate system the video card does not support anti-aliasing.
Wazoo
Douglas,

Thanks for the response. Yes, you were right. The problem got better when I changed from ClearType to Standard method of smoothing fonts, and cleared up totally when I unchecked font smoothing.

Are there any other options for improving text quality Does using DirectX to draw the text gain me anything

--Bruce
ahmedilyas
Here's a bit more information.

I am actually seeing two problems. One is generally poor quality text output.

The second is the color key leaking through. It seems the darker the text, the worse the problem. White text does not exhibit the problem at all, but black text displays an offset of itself in the key color.

While this problem happens on my system using GeForce 6200oc, I tried it on a different system and there was no problem at all. The text quality was good and I was not seeing the key color leak through.

Could this be a problem with this particular graphics card
Graphics (Text) Quality in an VRM9 Overlay Bitmap

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