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questions about practical use of Neat Image
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Traciatim

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Post by Traciatim »

I'm having a real problem getting a clean image off of my monitor for building a noise profile. I have an Olympus C5050 taking pictures at the highest res. My problem seems to present itself as I increase the sensitivity of the CCD (Through ISO setting) the shudder speed needs to be increased so as to get a good clear picture of the test pattern without it being incredibly bright and not well balanced. Here is the issue:

ISO 64: No Problem Shudder at 1/30
ISO 100: Shudder must be at 1/40+ and then picks up the VSync on my monitor as a band in the picture.
ISO 200-400: Shudder must be 1/60+ which has same issue.

I've tried adjusting the frequency of the monitor. Though at 1600x1200 the monitor goes only up to 85Hz. If I decrease my resolution to something like 800x600 to have a refresh of 120Hz I find I get a really nasty moiré pattern when I take the shot. Almost like the camera is picking up a strange pattern in the pixels, which I would assume will ruin the noise profile. I havn't tried resolutions in between, I assume each of them will have the same issue to a lesser degree.

Any idea on how to build profiles for the higher sensitivity settings?
NITeam
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Post by NITeam »

You can print the calibration target on a sheet of paper and then shot it. This will eliminate banding.
Regarding the changing shutter speed, you can then vary the power of light, which illuminates the paper, the to get different shutter speed.

Hope this helps.

Vlad
Traciatim
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Location: Saint John, NB
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Is it just me being picky?

Post by Traciatim »

I'm not too sure if it's me being picky, or maybe I'm doing something wrong. When I print this on paper on the lighter colours I'm getting paper grain able to be seen through the ink and also because of the method my printer usues to print images I'm also getting dithering patterns in the ink which could be mistaken by software looking for patterns of noise.

I was under the impression that in order to get a representation of what noise actually comes from the camera and it's various steps to making an image that you would want to remove as many possible other factors in order to achieve a clean (well, clean noise) result? Will having the shot slightly out of focus remove any possibility of interferance from the medium which the image was captured?
NITeam
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Post by NITeam »

You are right, taking an out-of-focus shot will eliminate unnecessary patterns. This is exactly what we recommend in the profiling instructions:
http://www.neatimage.com/testtarget.html

Hope this helps.

Vlad
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