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Author Topic: 10D image problems - horizontal lines at high ISO  (Read 9412 times)
neil
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« on: July 29, 2003, 01:24:01 PM »
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That's a 1000 pixel wide JPEG.  They are perceptible in the lower third of the image.  Try a better monitor.
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JJP
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« Reply #1 on: July 29, 2003, 06:10:29 PM »
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Neil,
I can see them with my laptop monitor.  But like the rest who responded, I don't know what the cause is.  
Were you using some kind of graduated but defective Cokin filter or the like?
Jules
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drew
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« Reply #2 on: August 08, 2003, 09:49:37 AM »
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Neil,
Camera is faulty, pure and simple. It is not a shutter fault and nor is it moire.
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« Reply #3 on: August 11, 2003, 11:43:01 AM »
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jjp,
Sorry, could'nt resist a cheap laugh at your expense, probably 'cause I am a cheap person.
dvl,
Sorry, this does not look like the same problem, or even if it is a problem at all. It is the context that concerns me. The image that started this thread clearly shows a fault, but I am not so sure that yours does.
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Bartone
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« Reply #4 on: August 11, 2003, 11:02:48 PM »
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this looks like an exposure 'wave' that compounds against the shutter - a flourescent issue using a particular shutter speed, and/ or ISO. There's a particular frequency to it, and I'd bet it's measureable to a timing of the 60 mHZ of the electricity of the light. Didn't use a strobe, or natural light, huh?

What do I win if I'm right? ;-)

bartone
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neil
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« Reply #5 on: July 29, 2003, 10:31:32 AM »
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here's one image as an example.  Its shot under florescent light with a window to the right, AWB, ISO 800, 1/400s, f2.8, 50mm1.4 used.  
  
  The bands should be noticable in this large an image.  The bands do not always occur, or else I'm not always percieving them.  This image has the contrast boosted after a R+G channel mix to get the B+W tonality.  The bands are strongest in the RED channel.  The camera preferences were on one 'level' boost for sharpen and one level reduction for contrast.  JPEG smooth.  Can't think of anything else.
  
  Any ideas what this is?  Its very distracting to the image.  Is there any way to filter them out? or is this something that needs to go back to canon?
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Rainer SLP
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« Reply #6 on: July 29, 2003, 02:34:07 PM »
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Hi Neil,

I have been looking at that and frankly it is quite hard to make up my mind what it could be.

Why do you not make some test shots by increasing the iso and see if it comes up.

I do not have a 10D but a 1Ds but up to now never got something similar.

Was the camera warm or cold?

Have you changed the Flash Card?

But it mostly looks similar to a scan where you increase the shadows a lot and then get the lines, which I interprete as a difference in the sensor, but here you do not scan linewise you have for each pixel a sensor and so you should not get lines.

Can you put somewhere the RAW file so I could experiment with it and see if by working on this image I get the same lines or bands?
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regards Rainer

please visit www.rsfotografia.com


Thank You
neil
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« Reply #7 on: July 29, 2003, 03:29:05 PM »
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Quote
Was the camera warm or cold?

Have you changed the Flash Card?

But it mostly looks similar to a scan where you increase the shadows a lot and then get the lines, which I interprete as a difference in the sensor, but here you do not scan linewise you have for each pixel a sensor and so you should not get lines.

Can you put somewhere the RAW file so I could experiment with it and see if by working on this image I get the same lines or bands?  

Camera warm.  Shooting heavy, 1frame a second or so.  Files before and after this the same effect happens irregularly.



This is the 'raw'(no levels adjust) red channel.  The image was shot in JPEG smooth.  The lines are not in the other channels.  I found the lines in a semingly random number of files.  Not a high number, but enough to be concerned.  I thought it might be some result of moire, but I found the same effect in a shot of a bride's back - an expanse of smooth skin (there in the red channel as well).  

If you want I'll e-mail you the original JPEG.
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sergio
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« Reply #8 on: July 29, 2003, 06:55:47 PM »
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I tried the following with my 1Ds : made a shot of a dark night sky with a very shy moon. It was a couple second exposure. After I had it in PS I moved the levels slider aggresively to one side and the image posterized (normal) but some very strange vertical banding appeared in the unusable posterized image. I repeated the test and it happened again. Unfortunately I don't have the image anymore. Check iy out for yourself.
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X-Re
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« Reply #9 on: July 30, 2003, 08:52:17 AM »
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It's grain of salt time - I'm considering buying a 10D, but haven't had a chance to play with one extensively, or anything....

     What you have here is not a moire effect or something like that - you might expect to see moire in the bride's vail (notice how *sharp* the patterning is, there... wow, neat  As I understand moire, it tends to happen in "high frequency" areas of the image - (excuse my lame attempt at explanation) ie areas with lots of lines next to each other or something like that. Test targets are a good example, for instance...

     Also, notice how the frequency of the lines increases towards the bottom of the picture? Then there's sort of a break (just above the pendant on her necklace), and then a few more lines?? Do the other pictures you see this problem with exhibit the same pattern?? Can you post a red channel from one of those, just for comparison's sake??

     To me, it looks like some kind of interference pattern, or processing artifact. Having never debugged this sort of situation before, I'd tend to suspect something in the realm of: faulty sensor, faulty in-camera processing algorithms, or maybe a little of both. If it's in firmware, it could theoretically be fixed w/ a firmware update.

     Have you thought about running a couple of examples past Canon, and see what they say?? This doesn't appear to be normal to me (again, remember that salt!

     Oh, BTW, nice shot!!! I've come back a couple of times to this thread to look at your picture

     Dave
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neil
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« Reply #10 on: July 30, 2003, 09:26:03 AM »
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I'll be on the phone with Canon today.  It might just be the excuse I need to buy the third camera...  If you're still on the fence about the 10D don't let this hold you back.  I love these images and I think its only happening in one of my cameras.

I'm Mac impowered so Neat image is not an option.  If you want me to e-mail you the file you're welcome to try it...
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Jeff Donald
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« Reply #11 on: July 30, 2003, 10:13:52 PM »
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I've seen similar effects in DV that I've attributed to 8 bit rounding errors that lead to posterization.  Adding a little noise breaks up the pattern and the banding disappears.
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gabrielma
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« Reply #12 on: August 07, 2003, 09:23:43 PM »
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I tried to reply earlier, but there is an obvious JavaScript bug with the posting system in this forum.  This is my first post here, btw.  (and this is a copy and paste job from my notepad)

I have seen this kind of effect before, and it was with my very first Canon body: the EOS 630.  The veridict was it needed a new shutter curtain.  The effect, though, was the inverse of what I see in your shot:  hardly any image on top, darker on the bottom, gradually, yet not linearly (as in, pseudo-exponentially).

You may have a damaged shutter curtain.  Sorry

---Gabriel
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---Gabriel MA
drew
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« Reply #13 on: August 08, 2003, 09:51:36 AM »
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Attractive bride attractively shot BTW
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Andrew Richards My Webpage
dvl
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« Reply #14 on: August 09, 2003, 12:44:37 PM »
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I hav enoticed the horizontal lines too. I am not sure they are a CCD defect, as this is a planar array and these artifacts are clearly linear. It could be a clock issue, or more likely a filtering issue.

It's not really an issue in most photographs- I see it only with extreme color corrections that are far beyond what one would use in practice.

My lines look a little different than the ones originally posted. Here is a small sample.

I have used channel mixer and contrast to enhance these lines. It's also been resized to 25%.

I have seen worse cases than this but I can't seem to find any right now.



There is not much practical consequence to these lines (so far, anyway) but I suppose I will give Canon a call.
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cw
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« Reply #15 on: August 11, 2003, 11:52:32 AM »
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After further analysis of some more of my images, I am pretty sure that my camera has the same artifact.  It is minor, though, and imperceptible in almost all cases, and I cannot find an example that is as eggregious as the one that started the thread.  Later today I will shoot some flat field tests to see if I can duplicate it better.

watts
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cw
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« Reply #16 on: August 11, 2003, 07:43:18 PM »
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Yes I will try to do it tonight. Unfortunately I don't own most of the images that I've taken with this camera (retained by the client) but I will figure something out!

chris
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cw
keith smith
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« Reply #17 on: August 12, 2003, 02:19:59 AM »
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I wonder if this is more a mechanical problem.

The image was taken at 1/400.  the problem is only in the lower part of the image, so it might start at about where the first shutter curtain stops, possibly causing some judder in the second curtain which will be at about where the lines start.  

Just a thought.

keith
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JJP
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« Reply #18 on: July 29, 2003, 12:07:31 PM »
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Where are the "bands" located in your image?
Jules
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JJ
Joe Hardesty
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« Reply #19 on: July 29, 2003, 02:35:17 PM »
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I can certainly see the bands in your image, but don't have a clue what they are--never seen anything like it.

Just a guess, but is it possible it has something to do with the combination of light source and shutter speed, sort of like the old problem of phtographing a TV picture?
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Thanks for the memories!
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