[Elphel-support] (no subject)

[201图像所]

Hello,

Thanks for your advice firstly.The pictures of vedio are good now
after adjusting the Lens aperture.

But,i fall in the trouble of vignetting recently.I find you use the
method of Function approximation.I look up some papers,the Function is
f(i,j) = cosh(rx*(x-x0))*cosh(ry*(y-y0)) +c .However,yours is
f(x,y)=p*(x-x0)^2 +q*(y-y0)^2 + c    ----->>    f(x,y)=AX*x^2 + BX*x +
AY*y^2 + BY*y + c.
Could i ask you how to get the Function ,and how to set the initial
value of AX、AY、BX、BY and C?

Song Rui

2014-05-01 2:54 GMT+08:00 Oleg <support-list at support.elphel.com>:
> Hello,
>
>> I have tried the way you suggested.I set the frame rate 25 fps,and the
>> exposure time is 35ms.Then the frame rate is correct,but the picture
>> of vedio is still bad in the natural light not the very low light.When
>> I set the exposure mode to autoexposure,the exposure time is about
>> 400ms.The vedio is normal then.But the frame rate is about 2 fps at
>> that time.
>
>
> What kind/name of lens do you have? Does it have adjustable aperture?
> Check it. With the aperture wide open you should get exposure less than 1ms
> at daytime.
>
>>
>> The camera can get 640*480 in 25fps just using 3M bandwidth,do you use
>> Inter prediction or intra prediction in the camera? Which part is used
>> as Caching the pre-frame?ddr sdram or sdram?
>
>
> There's no inter/intra prediction.
> The pixels from the sensor are buffered into ddr sdram before compression -
> after compressor the image is written into the frame buffer accessed by the
> cpu.
>
> Best regards,
> Oleg Dzhimiev
> Electronics Engineer
> phone: +1 801 783 5555 x124
> Elphel, Inc.