Re: OMAP3 ISP previewer Y10 to UYVY conversion

Chris Whittenburg
2015-04-16T18:05:31Z

On Tue, Apr 7, 2015 at 10:51 AM, Laurent Pinchart
<laurent.pinchart@ideasonboard.com> wrote:
> Black level compensation is applied by the CCDC before writing raw frames to
> memory. If your raw frames are correct BLC is probably not to blame.
>
> The default contrast is x1.0 and the default brightness is +0.0, so I don't
> think those should be blame either.
>
> I suspect the RGB2RGB conversion matrix to be wrong. The default setting is
> supposed to handle fluorescent lighting. You could try setting the RGB2RGB
> matrix to the identity matrix and see if this helps. See
> http://git.ideasonboard.org/omap3-isp-live.git/blob/HEAD:/isp/controls.c#l184
> for sample code.
>
> Another matrix that could be worth being reprogrammed is the RGB2YUV matrix,
> which also defaults to fluorescent lighting. Sample code to reprogram it is
> available in the same location.

I tried changing the rgb2rgb matrx to the identity matrix:

{0x0100, 0x0000, 0x0000},
{0x0000, 0x0100, 0x0000},
{0x0000, 0x0000, 0x0100}

And the csc (rgb2yuv) to this:
{256, 0, 0},
{0, 0, 0},
{0, 0, 0}

But I couldn't see much, if any, difference.

However, when I forced the gamma correction to be bypassed, it seemed to fix it.

Does that make sense? I guess I don't understand it enough to
understand if gamma correction would have compressed all my luma
values.

Thanks,
Chris