Faint horizontal lines on 300D images

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

 

i'd love to eyeball the pic, but no way I'm going to download a tif of
indeterminate size.. you have a resampled small jpeg or a jpeg crop of the
offending area you could post?

k

 

It's 259.9KB.

 

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

Try at least 800x600 using JPEG.

 

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.

 

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.

 

Zip. Mark up the image (draw some arrows or whatever) to point to
what you see. Otherwise, the only remarkable artifacts in this image
are due to JPEG, which you must already know about.

 

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.

 

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.

 

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.

 

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.

 

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.

 

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.

 

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.