[Elphel-support] Questions about the sensor in Elphel353

[Andrey Filippov]

On Tue, Sep 6, 2011 at 12:49 PM, Diana Carrigan
<DianaEJohnson at maxim-ic.com>wrote:

> Hello,****
>
> ** **
>
> We have a couple of questions I’m sure you guys can answer.****
>
> ** **
>
> **1)      **What is the sensor data format defaulted to? (RGB? YUV?)****
>
> **2)      **Does the sensor do an RGB to YUV conversion?
>
Diana,

Sensor data format (if you really mean the 'sensor', not the camera) is
Bayer encoded 12-bit data - you may find more details in the sensor
datasheet on Aptina web site (MT9P031). But if you mean FPGA/camera, than
there are several image formats available. Default is regular JPEG with
YCbCr 4:2:0, in that case the FPGA performs simple (bi-linear) demosaic
combined with RGB->YUV conversion

For higher quality we use JP4 format (explained here -
http://community.elphel.com/jp4/jp4demo.php ), with the compression set to
100% it preserves virtually all the data available from the sensor and
making it possible to fit the sensor output into the transmission/recording
bandwidth of the camera.


> ****
>
> **3)      **Can the Disk Recorder (or some other program) be used to
> create a data file of the video stream of the RAW RGB data (perhaps 5
> seconds worth of video stream)?
>
We have possibility top acquire raw frames from the camera, but that is only
for testing purposes, to make sure the compressed output matches the sensor
data. When compressing the raw data in JP4 format we keep compression errors
below the sensor noise floor, so using the actual raw data does not provide
you with more information. And it is not possible to record full
resolution/frame rate data in the camera in raw format - it would require
higher bandwidth but no image improvement.

JP4 requires post-processing and you may use ImageJ program with our plugin
(
http://elphel.git.sourceforge.net/git/gitweb.cgi?p=elphel/ImageJ-Elphel;a=blob;f=JP46_Reader_camera.java)
that reads the JP4 images (you can split the JP4-based video file into
frames -
http://elphel.git.sourceforge.net/git/gitweb.cgi?p=elphel/miscellaneous;a=blob_plain;f=split_mov.php)
together with Exif data (including custom MakerNote that includes
additional camera settings information) and converts them to raw Bayer
mosaic data un-applying in-camera conversion (such as analog per-channel
gains, gamma correction) and resulting in floating point TIFF images that
can be processed by different programs.

We also have programs to convert JP4 movies into regular ones.

Andrey



> ****
>
> Thanks for your help..****
>
> ** **
>
> Diana Carrigan****
>
>
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