Faint horizontal lines on 300D images

Discussion in 'Australia Photography' started by Rowan Crowe, Jul 28, 2004.

  1. Rowan Crowe

    Rowan Crowe Guest

    I noticed some faint horizontal lines on a 300D print yesterday. I had
    seen them on my new CRT monitor previously but I assumed that it was a
    CRT oddity (I'm still getting used to moire after using an LCD for 3-4
    years). At the time of the print I thought that I had a blocked jet,
    but after some more editing just now I've realised that since both the
    CRT and printer display it, the issue appears to be with the camera.

    Is this normal? It shows in areas where there is a fair amount of one
    colour, like sky. I'm hoping it's a normal quirk of the sensor rather
    than something more serious like a half dead multiplexing transistor.

    Here's a sample 1:1 crop of some sky, it's not the best example but
    hopefully the lines are apparent.

    http://media.sensationcontent.com/rowan/300D-horizontal-lines.tif
     
    Rowan Crowe, Jul 28, 2004
    #1
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  2. Rowan Crowe

    k Guest

    k, Jul 28, 2004
    #2
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  3. Rowan Crowe

    Mark M Guest

    It's 259.9KB.
     
    Mark M, Jul 28, 2004
    #3
  4. Rowan Crowe

    Jim Townsend Guest

    The image is 340x247.. It's thumbnail size.. Too small to see
    any detail.

    Try at least 800x600 using JPEG.
     
    Jim Townsend, Jul 28, 2004
    #4
  5. Can't tell from your sample. I have a 300D and sometimes get faint
    horizontal lines from my printer, but never see them on my monitor.
     
    Charles Schuler, Jul 28, 2004
    #5
  6. Rowan Crowe

    scott Guest

    I might be wrong, but I think the detail he wants us to see is quite small.
    Try zooming in on the image and notice the weird lines of 5 or 6 pixels that
    just appear to be wrong. Similar images from my 300D certainly don't have
    that problem. It looks as if something in the software/hardware is wrong.
     
    scott, Jul 28, 2004
    #6
  7. Rowan Crowe

    eawckyegcy Guest

    eawckyegcy, Jul 28, 2004
    #7
  8. Rowan Crowe

    Alfred Molon Guest

    My personal guess is that you shot that image at a high ISO and that the
    camera applied a lot of colour noise reduction. When you apply a lot of
    colour noise reduction you get that effect.
     
    Alfred Molon, Jul 28, 2004
    #8
  9. Rowan Crowe

    sinatraesque Guest

    Rowan,
    Can you go into photoshop and look at the individual red, green, and blue
    channels? You may find one of them is inordinately noisy. But post a full
    size JPG or a crop (at 100%) then maybe we could figure it out.
     
    sinatraesque, Jul 29, 2004
    #9
  10. Rowan Crowe

    Glen F Guest

    My personal guess is that you shot that image at a high ISO and that the
    Sure looks noisy. Even just the interaction of jpeging and noise might
    produce strange artefacts.
     
    Glen F, Jul 29, 2004
    #10
  11. Rowan Crowe

    usenet Guest

    Kibo informs me that (Rowan Crowe) stated
    that:
    The only faults I can see in that crop are lots of fine (5-10 pixel)
    compression artifacts, that look a bit like lots of tiny scratches. If
    that's what you're talking about, the problem is that you're
    over-compressing your images. If you're shooting JPEGs (rather than
    RAW), you should check the image quality settings you're using in both
    the camera & whatever software you're using to process your photos.
     
    usenet, Jul 29, 2004
    #11
  12. Rowan Crowe

    usenet Guest

    Those marks are JPEG compression artifacts. You get them if the JPEG
    quality is set too low in the camera or the editing software. Too many
    open-edit-save cycles images stored in JPEG format can also cause the
    same problem.
     
    usenet, Jul 29, 2004
    #12
  13. Rowan Crowe

    Rowan Crowe Guest

    Actually I shoot in RAW mode, and there is no lossy compression (that
    I am aware of) anywhere in my workflow. I presume those artifacts are
    the result of in-camera sharpening and the de-mosaicing process. I
    tried an ISO100 test shot with a 50mm prime, set all contrast and
    sharpening adjustments etc to neutral/0, and I could still see those
    when I zoomed in.

    As far as the original problem goes, I've looked again and I'm not
    entirely sure it really is the camera. I'll do some more tests with
    prints and another monitor to try to find a conclusive answer.
     
    Rowan Crowe, Jul 29, 2004
    #13
  14. Rowan Crowe

    eawckyegcy Guest

    You aren't making sense. In "raw" mode there is _no_ "in camera
    sharpening" nor a "demosaicing process". All that happens in your
    computer.
    None of those settings have any effect on the "raw" image. (Or they
    shouldn't have any effect if the word "raw" has any meaning.)
    Others can see them on their monitors, so further monitor tests won't
    prove much. Ditto for prints (since you can see them on your monitor,
    why waste paper?) If you want some idle speculation: the Nikon D70
    applies a median filter to its so-called "raw" images. You should
    read this webpage carefully:

    http://astrosurf.com/buil/d70v10d/eval.htm

    It will suggest a far more germane experiment to conduct.
     
    eawckyegcy, Jul 30, 2004
    #14
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