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I project a pattern on a reflecting object and I capture the reflected pattern (reflected via the object) using a CCD camera. However, the reflected pattern has a very low contrast (due to volume scattering) as I barely could see the project pattern.

Is there anyway to increase the contrast in this case?

Many thanks in advance for your support or for any suggestion where I can find an answer to my question.

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    $\begingroup$ Volume scattering can be suppressed with time resolved imaging but that requires an ultrafast laser source and a camera with ns aperture width. The principle is, that scattered photons have to take a longer path than those reflected by the object, so they are arriving at the camera at a different time. My guess is, that you may not have that kind of equipment, though? If the scattering is wavelength dependent, choosing an ideal frequency of your light (usually as low as possible) will help. There are also methods like multi-photon excitation for biological deep tissue imaging. $\endgroup$ – CuriousOne Aug 23 '14 at 13:57
  • $\begingroup$ Ultrafast latser source is not possible in my case as I generate the pattern on a monitor (white light source) as well as the camera (I didn't understand what you meant in ns aperture width). Therefore your last solution is not applicable as well because I can't use a monitor with different wavelength unless the projected pattern will still be presented if we use a light converter from white light to infrared (I believe this is not possible). Thank you for your possible solutions and I liked your way of thinking. I would like to get more ideas from you that could help me to find my solution. $\endgroup$ – Jack_111 Aug 25 '14 at 17:11
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    $\begingroup$ Sorry that I couldn't help... volume scattering is a hard problem. Good luck! $\endgroup$ – CuriousOne Aug 25 '14 at 19:41
  • $\begingroup$ Would Photography be a better home for this question? $\endgroup$ – Qmechanic Oct 28 '14 at 15:59
  • $\begingroup$ @Qmechanic I think there's some interesting physics here. CuriousOne's comment shows this: also there is some interesting optics in the problem of volume scattering (principles of confocal and multiphoton microscopy) $\endgroup$ – WetSavannaAnimal Feb 8 '15 at 9:24
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Increasing the contrast on the projected object might help some, as well as changing the lens, but probably the best (easiest and cheapest) way to increase the contrast on the final image is to edit it after the fact, using some image/video manipulation software.

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  • $\begingroup$ You mentioned increasing the contrast on the projected objec, how?! Changing the lens, which specification of the lens do you think will help (Bigger or smaller aperture)? Could you explain it more please? The last solution is not a solution as the manipulation of the scalling of the contrast will scale the noise on the taken image as well and that is what I don't need! Any other suggestions? $\endgroup$ – Jack_111 Aug 25 '14 at 17:12
  • $\begingroup$ To increase the signal-to-noise ratio you could create a HDR image. Take a series of pictures with different exposure times and combine them either manually or use a HDR software. $\endgroup$ – Aziraphale Aug 26 '14 at 7:31
  • $\begingroup$ Of course you have to use the lowest possible sensitivity value of your camera. Usually it is 80 or 100. The higher this value, the higher the noise level will be. $\endgroup$ – Aziraphale Aug 26 '14 at 7:35
  • $\begingroup$ @Aziraphale Why images with different exposure times? The noise could be supressed by taking different images and averaging them and it is not necessary with different exposures. But what is the advantage of different exposure time? Could you please explain more $\endgroup$ – Jack_111 Aug 26 '14 at 12:12
  • $\begingroup$ HDR means that you artificially increase the dynamic range (i.e. the range between over-exposed and under-exposed areas of an image) by combining images taken with different exposure times. Bright areas (e.g. sky, clouds) are well displayed on images with a short exposure time, whereas shadowy areas need longer exposure times to reveal details. The combination will show ALL details. So, if your pattern has darker and brighter areas you can simulate a higher sensitivity with low noise. $\endgroup$ – Aziraphale Aug 26 '14 at 12:44

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