[Elphel-support] 答复: 答复: 答复: 答复: 答复: 答复: sync stereo with lidar

[Tao Zhang]

Hi Andrey,
We now can restore 12 bit as the method you described. But that 12 bit is lossy. We want lossless 12 bit or 10 bit data from camera to verify our algorithm. Can you help give that guide?

Thanks

Tao Zhang
章   涛

发件人: Allen Yin
发送时间: 2018年3月27日 16:34
收件人: Elphel Support <support-list at support.elphel.com>
抄送: Pioneer Li <pioneer.li at blacksesame.com.cn>; Tao Zhang <tao.zhang at blacksesame.com.cn>; Qun Gu <qun.gu at blacksesame.com>; Winston Zhang <winston.zhang at blacksesame.com.cn>
主题: 答复: [Elphel-support] 答复: 答复: 答复: 答复: 答复: sync stereo with lidar

Hi Andrey,

Could we bypass the “gamma” module in the FPGA?  We want the original raw data from sensor.

Thanks,

Allen Yin

发件人: Elphel Support <support-list at support.elphel.com<mailto:support-list at support.elphel.com>>
发送时间: 2018年3月22日, 星期四 23:23
收件人: Allen Yin <allen.yin at blacksesame.com.cn<mailto:allen.yin at blacksesame.com.cn>>; Elphel List <support-list at support.elphel.com<mailto:support-list at support.elphel.com>>
抄送: Pioneer Li <pioneer.li at blacksesame.com.cn<mailto:pioneer.li at blacksesame.com.cn>>; Tao Zhang <tao.zhang at blacksesame.com.cn<mailto:tao.zhang at blacksesame.com.cn>>; Qun Gu <qun.gu at blacksesame.com<mailto:qun.gu at blacksesame.com>>; Winston Zhang <winston.zhang at blacksesame.com.cn<mailto:winston.zhang at blacksesame.com.cn>>
主题: Re: [Elphel-support] 答复: 答复: 答复: 答复: 答复: sync stereo with lidar

Allen,
~/.imagej/Eyesis_Correction.xml is not really needed - it just hides/reveals some experimental buttons on the interface
This is the contents of such file:
<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE properties SYSTEM "http://java.sun.com/dtd/properties.dtd">
<properties>
<comment>last updated Thu Sep 08 14:09:47 MDT 2016</comment>
<entry key="ADVANCED_MODE">False</entry>
<entry key="DCT_MODE">False</entry>
<entry key="MODE_3D">False</entry>
</properties>


result.jpg looks correct. It should be super-contrast as it is linear, so it CAN NOT be saved as JPEG - it needs either 16 bits or 32 bit TIFF as when you save it from imageJ (save as tiff). And it is "monochrome" - each pixel corresponds to the sensor pixel value. For you application I would recommend to use just green subchannel (checkerboard pattern, half of all pixels) - in that case you do not need to have aberration correction.

Your plots for gamma seem correct too, to be sure I need to look into the code again - I wrote that part several years ago.

Gamma is not changed automatically in the camera, but you may change it using one of the interfaces - camvc of just parsedit. In addition to the power (0.57) there is another parameter - dark level - the sensor adjusts its ADC to have output level of 160 (on 4096 scale) or 10(256) for the complete darkness, so-called "fat zero".

Gamma is applied inside the FPGA and parameters are saved in the Exif header, so for processing it is possible to "undo" gamma and restore linear scale.

Andrey

---- On Thu, 22 Mar 2018 00:58:53 -0700 Allen Yin<allen.yin at blacksesame.com.cn<mailto:allen.yin at blacksesame.com.cn>> wrote ----
Hi Andrey,

There seems to be an another error, “2.jpg”.

I have some doubts, could you please help me?


1.     Does gamma value remain unchanged when camera works ?  Who realize this gamma mapping, sensor or ISP?


2.     When gamma0 = gamma1 = gamma2= gamma3 = 0.57, gamma_scale0 = gamma_scale1 = gamma_scale2 = gamma_scale3 = 1024,


gamma mapping  is  Vout = a*Vin^gamma, a = 2.23  gamma = 0.57 , is it right? If not right, could you tell me the right? I use this gamma curve to convert the 12bit raw data, “result.jpg” is the result.




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