Lumix GX7 Black / Dead Pixels

Discussion in 'Panasonic Cameras' started by SC489, Oct 11, 2014.

  1. SC489

    SC489 Mu-43 Rookie

    19
    Aug 2, 2014
    I've noticed a few black / dead pixels in evenly lit areas e.g. sky. These are only visible at high (400%) magnification. I tried the Pixel Refresh and Sensor Cleaning functions but they are still there.

    I'm wondering if this is normal and I should just accept the dead pixels or whether I should request a replacement since the camera is only 2 months old. I can see looking back over the images that the dead pixels have been there since the camera was new.

    I thought the Pixel Refresh function might solve the problem but the manual (p60) only refers to correcting 'bright spots'.
     
  2. seadragon

    seadragon Mu-43 Regular

    52
    Jan 3, 2013
    The pixel refresh is only for "hot" or "stuck" pixels. The ones that are always on.

    However, as far as dead pixels go, it's normal to have a few on any pixel based technology. It usually only becomes an issue if they are all clumped together in one spot.

    If only visible at 400%, I wouldn't even worry about it. I only view things at a max of 100%. Anything more is surely bound to disappoint in any camera.

    Enjoy your GX7, it rocks!
     
  3. Tinderbox (UK)

    Tinderbox (UK) Mu-43 Regular

  4. seadragon

    seadragon Mu-43 Regular

    52
    Jan 3, 2013
    Interesting...

    The GX7 manual just mentions bright pixels:

    "Imaging device and image processing is optimized when the camera is purchased. Use this
    function when bright spots that do not exist in the subject get recorded."
     
  5. SC489

    SC489 Mu-43 Rookie

    19
    Aug 2, 2014
    I've now done some more research on this and the plot thickens:

    1. I don't see any dead pixels viewing a JPG image taken under the same conditions.

    2. Using DXO Optics Pro 9 as the RAW converter with no processing, I see a coloured cross. See the enclosed screenshot at 400% magnification.




    DXO Optics Pro 9 Screenshot

    The dead pixel is removed if I enable Noise Reduction and use a Dead Pixel setting higher than 6.

    3. Using ACDSee Pro 7 as the RAW converter with no processing, I see a single black pixel. See the enclosed screenshot at 400% magnification.




    ACDSee Pro 7 Screenshot

    The dead pixel is removed if ACDSee noise reduction is enabled.

    4. I don't see any dead pixels using Silkypix (supplied with the camera) or Windows Photo Viewer. I don't know how to disable noise reduction in Silkypix to see is this reveals any dead pixels.

    Please advise:

    1. I have about 6 of these dead pixels spread over the image. Should I be concerned about returning the camera since they are obviously easily removed by JPG and RAW noise processing?

    2. Why does DXO Optics Pro 9 show a magenta cross with no RAW processing applied, wheres ACDSee shows a single dead pixel?

    3. I don't have Lightroom. How does it handle RAW processing of dead pixels?
     
  6. Tinderbox (UK)

    Tinderbox (UK) Mu-43 Regular

    You could try heating up the sensor by recording video for a few minutes and then as fast as you can do a pixel mapping while the sensor is still warm, I don't know if this will do anything it might make it worse, the risk is yours but it would make it easier to get a replacement.

    John.

    dead-pixels_zpsedbd1650.
     
  7. SC489

    SC489 Mu-43 Rookie

    19
    Aug 2, 2014
    I've had a reply from DXO stating:

    Dead pixels processing in Optics Pro reduces or eliminates “dead” pixels camera sensor elements that for whatever reason fail to record the incident light correctly and show up as bright spots in the image. This happens mostly at high ISO settings, in dark images, and in long-exposure shots, though it can also happen at lower ISO settings. Optics Pro is designed to mark these pixels for easy reference using a magenta cross, as you noted, whereas ACDSee uses a different method of marking. Optics Pro does a thorough analysis of the image to try to identify as many dead pixels in the image as is possible.


    I've also analysed the whole GX7 image for 'dead' pixels and enclose a file showing all pixels marked by DXO Optics Pro as 'dead' pixels. I've inserted X above each DXO Optics Pro magenta cross so you can see where they are.

    I GX7 Dark Pixels Mapped.

    Please advise:

    1. Are these detections by DXO Optics Pro really dead pixels or just pixels flagged by the RAW processing algorithm for specific analysis?

    2. Is this level of dead pixel defects typical for a new GX7?

    I'm not too concerned since I don't see these dead pixels in JPG images nor in some other RAW convertors (e.g. Silkypix supplied with the camera). They are also removed as soon as I enable the DXO dead pixel function