Blending text and graphics for display

Abstract

Text and graphics elements may be alpha blended in a way to reduce flicker when the text or graphics are display by a processor-based television receiver. The alpha values are used to intelligently smooth pixels adjacent the element to create television text and graphics.

1. A method comprising:
 acquiring a graphics primitive to be displayed on a television receiver; and  
 selectively adjusting the transparency of portions of the primitive relative to a background to reduce flicker when the primitive is displayed on a television receiver by smoothing the horizontal edges of the primitive based on the color of the primitive and the color of the background.  
 
     
     
       2. The method of  claim 1  including acquiring the primitive from a library. 
     
     
       3. The method of  claim 1  including forming a bit map of the primitive for overlaying on said background. 
     
     
       4. The method of  claim 1  wherein selectively adjusting involves adjusting only a horizontal portion of said primitive. 
     
     
       5. The method of  claim 4  further including selecting at least two alpha values for a horizontal portion of said primitive and adjusting the depiction of said primitive in two stages. 
     
     
       6. The method of  claim 5 , wherein selectively adjusting includes modifying at least one row of pixels adjacent horizontal portions of the element. 
     
     
       7. The method of  claim 1  wherein selectively adjusting includes using alpha blending. 
     
     
       8. The method of  claim 7 , wherein selectively adjusting includes subtracting the color value of the primitive from the color value of the background color and multiplying the difference by an alpha value. 
     
     
       9. An article comprising a medium for storing instructions that enable a processor-based system to:
 acquire a graphics primitive to be displayed on a television receiver; and  
 selectively adjust the transparency of the primitive relative to a background to reduce flicker when said primitive is displayed on a television receiver by smoothing the horizontal edges of the primitive based on the color of the primitive and the color of the background.  
 
     
     
       10. The article of  claim 9  further storing instructions that cause a processor-based system to multiply an alpha value times the difference of a color value for the background color and the color value for the graphical primitive and to add the color value of the primitive. 
     
     
       11. The article of  claim 10  further storing instructions that cause a processor-based system to acquire a font and an alpha value from a database. 
     
     
       12. The article of  claim 9  further storing instructions that cause a processor-based system to alpha blend the horizontal edges of a graphical primitive. 
     
     
       13. The article of  claim 12  further storing instructions that cause a processor-based system to alpha blend the edges of a graphical primitive in at least two stages. 
     
     
       14. An apparatus to reduce flicker comprising:
 a processor; and  
 a storage coupled to said processor, said storage storing instructions to enable a graphics primitive to be acquired for display on a television receiver and to selectively adjust the transparency of the primitive relative to the background to reduce flicker by smoothing the horizontal edges of the primitive based on the color of the primitive and the color of the background.  
 
     
     
       15. The apparatus of  claim 14  including a tuner card coupled to said processor. 
     
     
       16. The apparatus of  claim 15  including a television receiver coupled to said processor. 
     
     
       17. The apparatus of  claim 16  wherein said storage includes a font database associated with alpha values that reduce flicker. 
     
     
       18. The apparatus of  claim 17  wherein said storage includes instructions to cause an alpha value to be multiplied by the difference of the color values of a background and primitive and to add the color value of the primitive. 
     
     
       19. A method comprising:
   acquiring a graphics primitive to be displayed; and        selectively adjusting the transparency of portions of the primitive relative to a background to reduce flicker when the primitive is displayed by smoothing horizontal edges of the primitive based on the color of the element and the color of the background.      
     
     
       20. The method of  claim 19  including acquiring the primitive from a library.  
     
     
       21. The method of  claim 19  including forming a bit map of the primitive for overlaying on said background.  
     
     
       22. The method of  claim 19  wherein selectively adjusting involves adjusting only a horizontal portion of said primitive.  
     
     
       23. The method of  claim 22  further including selecting at least two alpha values for a horizontal portion of said primitive and adjusting the depiction of said primitive in two stages.  
     
     
       24. The method of  claim 23 , wherein selectively adjusting includes modifying at least on row of pixels adjacent horizontal portions of the element.  
     
     
       25. The method of  claim 19  wherein selectively adjusting includes using alpha blending.  
     
     
       26. The method of  claim 25 , wherein selectively adjusting includes subtracting the color value of the primitive from the color value of the background color and multiplying the difference by an alpha value.  
     
     
       27. An article comprising a medium for storing instructions that cause a processor- based system to:      acquire a graphics primitive to be displayed; and        selectively adjust the transparency of the primitive relative to background to reduce flicker when said primitive is displayed by smoothing horizontal edges of the primitive based on the color of the element and the color of the background.      
     
     
       28. The article of  claim 27  further storing instructions that cause a processor- based system to multiply an alpha value times the difference of a color value for the background color and the color value for the graphical primitive and to add to the color value of the primitive.    
     
     
       29. The article of  claim 28  further storing instructions that cause a processor- based system to acquire a font and an alpha value from a database.    
     
     
       30. The article of  claim 27  further storing instructions that cause a processor- based system to acquire a font and an alpha value from a database.    
     
     
       31. The article of  claim 27  further storing instructions that cause a processor- based system to alpha blend the edges of a graphical primitive in at least two stages.    
     
     
       32. An apparatus to reduce flicker compromising:
   a processor;        a storage coupled to said processor, said storage storing instructions to cause a graphics primitive to be acquired for display and to selectively adjust the transparency of the primitive relative to a background to reduce flicker by smoothing horizontal edges of the primitive based on the color of the element and the color of the background.      
     
     
       33. The apparatus of  claim 32  including a tuner card coupled to said processor.  
     
     
       34. The apparatus of  claim 33  including a television receiver coupled to said tuner card.  
     
     
       35. The apparatus of  claim 34  wherein said storage includes a font database associated with alpha values that reduce flicker.  
     
     
       36. The apparatus of  claim 35  wherein said storage includes instructions to cause an alpha value to be multiplied by the difference of the color values of a background and primitive and to add to the color value of the primitive.