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Old Oct 29, 2004, 4:02 PM   #1
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I am a MSc Biometrics student currently undertaking a project to look into the effects of illumination on a facial recognition system.
I am using a puppet head against the system and testing the influences of lights that hit the dummy head from various positions in order to establish the limitations of the face recognition algorithm.
I am using the Sony DSC-V1 Digital camera and am trying to use the manual settings for the aperture settings and the shutter speed. I am having problems in clearly identifying which values to assign these two variables to give me the best results, as with other cameras that I have used which do not have the manual setting, have compensated in the light quality of the capture therefore providing me with incorrect data. Therefore forcing me to adjust the camera settings manually.
On the pictures I just want to show how the effect of illumination/light increases as I increase the level of light, with the camera providing me with real life pictures, not being altered in any way.

Your advice and assistance would be deaply appreciated.
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Old Oct 30, 2004, 9:10 AM   #2
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$habz wrote:
Quote:
, as with other cameras that I have used which do not have the manual setting, have compensated in the light quality of the capture therefore providing me with incorrect data. Therefore forcing me to adjust the camera settings manually.
On the pictures I just want to show how the effect of illumination/light increases as I increase the level of light, with the camera providing me with real life pictures, not being altered in any way.

IMO, you anwsered your own question already. If you had a definition of what should be a real life picture, then have to find out what setting give you the best response to your recognition algorithm. Picture recorded on film, or CCD, or whatever are altered in a certain way, anyway. The key is what you are looking for, for instance: contours, edge, color transition, contrast area , etc ......

The "best setting" on each camera is given in automatic mode, so you can be inspired by those values. They are displayed in record mode, or you can look at the exif after the shot.

In general, aperture + speed combination give you the correct esposure. Small aperture give you a maximum deep of field. Slow speed tend to give motion blur. High spped allow you to cach movement.

found this, hope that it brings to you some help ...

http://www.shortcourses.com/using/index.htm


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Old Dec 23, 2004, 11:23 AM   #3
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thanks for the link Kcan, it was very helpfull!

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Old Dec 23, 2004, 1:52 PM   #4
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Quote:
On the pictures I just want to show how the effect of illumination/light increases as I increase the level of light, with the camera providing me with real life pictures, not being altered in any way.
The human eye has a much greater ability to adjust to light changes than does a camera. I think you are going to have to use some intervention to get the pictures to show the same thing the eye would see after it adjusts.

If you keep the same camera settings in manual mode you will either get pictures too dark to recognize well in light the eye would have no problem with, or get blown highlights that reduce recognition as you increase the illumination.

Aperture priority is an automatic mode and will meter the shots so they have about the same brightness – maybe not what you want either.


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