How to convert YCrCb to RGB using FPGA?

[etrobin]

Dear all,

Anyone can show me how to convert YCrCb to RGB by FPGA???
The equation as .............

R = Y + 1.402 (Cr-128)
G = Y - 0.34414 (Cb-128) - 0.71414 (Cr-128)
B = Y + 1.772 (Cb-128)

Thank you for reply!!!

regards,
etrobin

 

[gliss]

ycrcb

That equation may not be quite right. Here is something to get you started.

//---------------------------------------------------------------
// red_pixel_reg = 19(y-16)/16 + 13(cr-128)/8
// grn_pixel_reg = 19(y-16)/16 - 25(cb-128)/64 - 13(cr-128)/16
// blu_pixel_reg = 19(y-16)/16 + 2(cb-128)
//---------------------------------------------------------------

//----------------------------------
// y_term = 19(y-16)/16 
//----------------------------------
always@( y_sub1 )
begin
    y_mult = 5'h13 * y_sub1;
end

//-------------------------------------------------
//   13(cr-128)/8
//   13(cr-128)/16
//-------------------------------------------------
always@( cr_sub1 )
begin
    cr_mult = 4'hd * cr_sub1;
end

//----------------------------------------------------
// add
// grn_pixel_reg = y_term - grn_cr_term - grn_cb_term
//-----------------------------------------------------
always@(grn_cr_term or grn_cb_term )
begin
    grn_term =  -grn_cr_term - grn_cb_term;
end

always@( y_term or grn_term )
begin
    grn_add = y_term + grn_term;
end

You need to register the values, normalize each term, perform two's complement if necessary, find the multiplicand, and perform the multiplication and addition. Not exactly trivial.

 

[hwb]

ycrcb to rgb formula

Hi etrobin,

perhaps a bit late, but Xilinx offers comprehensive information about color space conversion. Appnote xapp283 describes YCrCb to RGB, xapp637 the other way.
I came across this today while evaluating the Xilinx System Generator where they have a Simulink model for RGB to YCrCb.

HTH,
Holger

 

[shawndaking]

rgb to ycrcb

it also depend what is the format of the YCBCR. in most cases you will also
need to do upsampling of the YCBCR data and also some sort of filtering.

 

[Ralph80]

Re: YCrCb to RGB ???

Maybe this color space conversion description will be helpful.