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Canon 7D noise pattern

Discussion in 'Help Team' started by BrianWall, Aug 4, 2012.

  1. BrianWall

    BrianWall Well-Known Member

    I have noticed that when using Lightroom 4 to lift slightly underexposed shadows, it reveals an odd pattern of noise consisting of vertical fuzzy lines. This screen grab from LR with the view at 1:1 shows this with shadow slider to max to better show the effect. When set to the correct level with just a bit of detail in the shadows, the pattern is visible in A4 prints.

    I am most puzzled by the very distinct vertical lines. Is this something to do with the Bayesian filter or similar?

    The camera is a fairly new 7D and this effect occurs on all shots to some extent. This particular image was a studio twin flash setup at 1/200th at f16 ISO 200 and the image was just a tad underexposed.

  2. daft_biker

    daft_biker Action Man!

    Does it do the same in DPP?
  3. beejaybee

    beejaybee Marvin

    It looks to me like the readout noise is varying across pixel columns. Probably caused by trying to read the sensor too fast. (Which is why video mode is a Bad Idea to have on a still camera.)

    If the pattern is consistent, you should be able to get rid of it by making a flat frame (an image of an evenly illuminated white screen like a light panel, or an empty window on a computer display) with the same lens, at the same aperture & same ISO setting, and the same focus distance set. (The panel will be out of focus but this doesn't matter since there is no detail in the target anyway). Then apply flat frame calibration. The same technique cancels out corner fall off due to lens vignetting & dust specks on the sensor.
  4. BrianWall

    BrianWall Well-Known Member

    I haven't got DPP installed at present Andrew. Interesting to see if this is a Lightroom/ACR artifact. The idea of creating a mask is good but should it be necessary??
  5. PeteRob

    PeteRob Well-Known Member

    For you I hope it is an artifact, for me, ... was just going to buy lightroom this weekend as have to do some selective editing that cannot be done in DPP.. might wait now :)
  6. P_Stoddart

    P_Stoddart Well-Known Member

    I would assum you can export from DPP at 16bit per pixel for use in Lightroom. Thus not losing any information.
  7. BrianWall

    BrianWall Well-Known Member

    I've installed DPP (for the first time ever as I've always used LR!!) and tried to adjust it in the same manner as in LR although DPP has no shadow adjustment. Still, DPP seems to give a cleaner result with the noise less obviously vertical lines.

  8. PeteRob

    PeteRob Well-Known Member

    If you installed DPP that came with your camera it can be updated. There are shadow and highlight controls now. Looks like the vertical banding is still there. This is 100% view?

    PS update go to canon uk home page and follow software updates
  9. BrianWall

    BrianWall Well-Known Member

    I installed the original then updated it but missed the shadow adjustment! Tried it again but the adjustment made little difference to the effect. My workflow is set up for LR so I'll continue to use it, but I am interested if other canon DSLR users have noticed this. It may just be a 'feature' of the sensor. Adjusting noise in LR removes it at about 50% with 50% detail and low noise contrast. Sharpness was about 25% and didn't seems to accentuate it oddly.
  10. daft_biker

    daft_biker Action Man!

    Aye, it looks like it's quite a few verions old.

    Each time Canon release a new camera that shoots RAW there's an update to DPP to support it. Any other new features or improvements they've made seem to be bundled in with releases to support new cameras.

    I couldn't find one that supports the M but the one for the 650D (on windows) is here.
  11. PeteRob

    PeteRob Well-Known Member

    I did get lightroom (my goodness it is complicated cf DPP !) and I have blown up some shadow areas to maximum shadows boost from a 5D (no video) and a 1D IV (has video) but there is no banding like your shot I am afraid.

    I should have noticed you had updated DPP because the /ALO on the NR tab is not so old. If you feel inclined to test the newer still lens optimizer(sic) tool under the lens tab be warned it doubles the size of the raw file (basically I think it makes an internal copy) and the lens data needs to be downloaded. Previously, limited lens data (for perspective and vignetting control) was bundled.

    As noted DPP gets updated frequently. The list of supported cameras is given in the change description. It says always to update the EOS utility (for direct connection of camera to computer) to go with the DPP but this is not always backward compatible. The utility update install will (well it did in my case) copy the version needed for my 5D to a subfolder of itself but I had some interesting moments until I realised. The indiividual camera page on canon uk will have the latest compatible versions for that camera and they do maintain the pages for old models.
    Last edited: Aug 5, 2012
  12. daft_biker

    daft_biker Action Man!

    Same here....it's me that's a wee bit out of date with that:eek:

    How hard would it be to make DPP check for compatible updates though. I never used to trust them to update all the cameras on the Canon site but it looks like they do keep things up to date now....perhaps they've had to since they stopped supporting some old cameras in new versions of DPP.
  13. PeteRob

    PeteRob Well-Known Member

    yes that would be useful, but by same measure continous autoupdates get annoying too. I think all cameras are still supported. I did a spot check on the D60 and its page lists the latest version.

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