Re: What decides the Mono LCD gray scale?
From: cool_harber (cool_harber_at_hotmail.com)
Date: 12/30/04
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Date: Thu, 30 Dec 2004 20:42:27 +0800
3x,I have tested the palette as you said,but the display is also bad,
Maybe my lcd just can be used in 4bpp.
A few days ago,Someone told me another palette in newsgroup,here is the
code:
// RGB to YUV conversion is defined by CCIR 601 Standard as
// Y = 0.299*R + 0.587*G + 0.114 B
// Implementation :
// scale= 15
// Gray = (Red*299 + Green*587 + Blue*114)*scale/(1000*255);
By the way,I use v_pPaletteBuffer->palette[ 0xFF - i ] to inverted palette.
"voidcoder" <voidcoder@yahoo.com> 写入消息新闻:ebnNysa7EHA.3820@TK2MSFTNGP11.phx.gbl...
> 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.
>> >>
>> >>
>> >
>> >
>>
>>
>
>
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