Grainy Image

2006-07-25
2013-06-03
  • has anybody else noticed a grainy image off the Elphel 333 model.  I certainly have.  Is there any way to reduce or preferibly eliminate this.  I've tried puting the Jpeg quality to 99% and upping post-processing in mplayer, but no luck.  The grain remains.  thanks.  Also is there a way to grab an uncompressed still image off the camera.

    MIKE

     
    • Any samples of what you mean by "grainy"? what was the exposure duration?

       
      • Did you have the iris full open when filming in dark conditions?

        If not then the long exposure combined with the grain in the lens & the small section of the lens being used would = grain. Add to this the  the small section of the actual sensor (if you are filming at normal HD resolutions).This would equal a less then perfect image. 

        If there is not enough light getting to the sensor your frame rate will = less then the exposure & your frame rate will drop.

        You have to treat the camera in the same way as a movie camera & use a lot of light. 

         
    • 1920x816
      24 fps
      21 ms

      I'm not at home at the momment so I'll have to get a sample probably tomorrow sometime.  It's not horribly bad but is present.   Seems like the more light we use the less apparent it gets.  Kinda looks like some kind of interference or something like that.  Not to sure really.  Should I just email a sample to you then?

      thanks

      mike

       
    • Lots I've light, it does seem to help.  I didn't realize that a lens itself could cause grain.  interesting

       
    • Lots of light I meant to say. he. so how quick of a computer would one need to be able to capture video at 1920x816, 100% JPEG quality, 21ms, at 24fps.  Think a hyper threaded P4 with 2 gigs of RAM could hang with that?

       
      • Latin Andy
        Latin Andy
        2006-08-04

        If you want capture video(dump data to file) - you must have quickly HD. For displaying video with this resolution - you must have accelerated video card(ie ATI Radeon, NVidia). Which OS you uses?
        If you are dumping only - RAM may be 512-1024 MB
        But, which size of picture with 1920x816 100% (I don't have camera here now)? If size of picture are big - network device will not have time to send data during transfer of the full frame video