Re: What decides the Mono LCD gray scale?

From: voidcoder (voidcoder_at_yahoo.com)
Date: 12/29/04 

Date: Wed, 29 Dec 2004 14:35:46 +0100

Nothing special. Don't really sure that it is right, but
I'm using just everage RGB value for grayscale level.

eg.

 for(i=firstEntry;i<end;i++)
 {
       v_pPaletteBuffer->palette[ i ] =
            (((unsigned short)source[i].peBlue + source[i].peGreen +
source[i].peRed) / 3);
}

The better result is using inverted average value, eg

v_pPaletteBuffer->palette[ i ] =
           0x00FF ^ (((unsigned short)source[i].peBlue + source[i].peGreen
+
                            source[i].peRed) / 3);

Please test it and come back with comments (since I think
this is not really right way to calculate grayscale palette).

May be any1 can share some ideas on "how to calculate right
grayscale palette"?

"cool_harber" <cool_harber@hotmail.com> wrote in message
news:OnQDrka7EHA.2124@TK2MSFTNGP15.phx.gbl...
> Thanks,But my lcd display looks so bad,
> the text is more clear than the blurred icon or image!~
> Can you share me your palette source code?
> email:cool_harber@hotmail.com
>
> "voidcoder" <voidcoder@yahoo.com>
写入消息新闻:eLG5VDP7EHA.2316@TK2MSFTNGP15.phx.gbl...
> > If You want to use SA_Lcd driver for that - you are out of luck.
> > There are no support for true 4bpp mode. However you can use
> > 8bpp mode and turn on monochrome mode in the controller.
> > Then just setup your palette with grayscale entries
> > (modify DispDrvrSetPalette function). In this case You will have
> > 8bpp in frame buffer memory, 4bpp output and 16bit lookup palette
> > (where only lower 8bits are grayscale values). And of course
> > You have to setup other LCD contoller settings: timings, clocks etc.
> >
> > At least it works o.k. for me on PXA270.
> >
> >
> >
> > "cool_harber" <cool_harber@hotmail.com> wrote in message
> > news:eN2ZwbO7EHA.3076@TK2MSFTNGP15.phx.gbl...
> >> The mono lcd`s gray scale is decided by lcd controller or lcd itself?
> >> I have a mono lcd with 4 data pins and about 70 Hz frame frequence ,I
> >> want to use PXA255 to controll it.Do I get 256 scale gray?
> >> Any suggestion is appreciated.
> >>
> >>
> >
> >
>
>