Re: [Linux-uvc-devel] Fusion Resolution

[michel X. <mx...@ma...>]

Le Samedi 25 Février 2006 01:37, Luc Saillard a écrit :
> On Fri, Feb 24, 2006 at 04:55:18PM -0500, Gabriel A. Devenyi wrote:
> > uvccapture is really setup just to create JPEGs by using the MJPEG
> > frames. Since its built on the luvcview core, the YUYV capture is present
> > in the code, but I've not implemented a method to get it out. I'll dig
> > through and see if I can add a YUYV dump, but I'm not even sure of the
> > file formatting, so I'll have to do a little research. At the very least
> > I'll disallow
>
> The format is very simple. For each pixel you have two bytes (even: Y and
> U) or (odd: U and V). So for an image of 4x4, you have 32 bytes
>
>  0: YU YV YU YV
>  8: YU YV YU YV
> 16: YU YV YU YV
> 24: YU YV YU YV
>
> This is very simple but i've not (yet) found a good algorithm when resizing
> and converting to other colorspace. You see vertical line. One line will be
> blue, the other line will be green.
>
> Luc
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Luc,
Maybe try this one, I have set in luvcview to resize the gui part . In 
luvcview i only resize the xaxis as y is a constant, this one may resize the 
two axis.

#define ADDRESSE(x,y,w) (((y)*(w))+(x))

typedef struct YU {
    unsigned char Y0;
    unsigned char U0;
} YU;

/* Each pixels in the resulting figure need to be set. For each one take the 
nearest available in the original surface
If the last Chroma component is U take a V else take U by moving the index in 
the nearest pixel from the left 
This routine only deal with X axis you need to make the original picture with 
the good height */

static int resize(unsigned char *INbuff, unsigned char *OUTbuff,
		  int Owidth, int Oheight, int width, int height)
{
    int rx, ry;
    int xscale,yscale;
    int x, y;
    int Cc, lastCc;
    YU *input = (YU *) INbuff;
    YU *output = (YU *) OUTbuff;
    if (!width || !height)
	return -1;
    /* at start Cc mean a U component so LastCc should be a V */
    lastCc = 1;
    xscale = (Owidth << 16) / width;
    yscale =(Oheight << 16) / height;
    
    for (y = 0; y < height; y++) {
	for (x = 0; x < width; x++) {
	    rx = x * xscale >> 16;
	    ry = y * yscale >> 16;
	    if (((2 * rx + 1) & 0x03) == 3)
		Cc = 1;		// find V component
	    else
		Cc = 0;
	    if (lastCc == Cc) {
		/* no Chroma interleave correct by moving the index */
		rx -= 1;
		Cc = !Cc;
	    }
	    memcpy(output++, &input[ADDRESSE((int) rx, (int) ry, Owidth)],
		   sizeof(YU));
	    lastCc = Cc;
	}
    }
    return 0;
} 

-- 
Michel Xhaard
http://mxhaard.free.fr