从RGB图像确定照度 [英] Determine illuminance from RGB image

问题描述

有没有办法使用相机（网络相机或手机相机）作为光度计？手机相机可以抓取图片并获取RGB格式的数据，但任何人都试图确定照度值（在 lux ）？

我知道没有公式来做到这一点（如果我错了，请纠正我），但是是否可以模拟它，并获得照度的近似值？

解决方案

像所有的反光灯一样，你会遇到的问题是，你不能区分一个明亮的光线（高勒克斯） （低勒克斯）发光在轻的对象。换句话说，你得到的是亮度，而不是照明。

第二个问题是，你需要知道放大器增益，曝光设置（光圈值，曝光时间）传递函数（gamma）和其它信息，以能够获得图像中的像素的正确光度解释。但是，如果您有这些信息，您可以忽略像素数据，只需使用曝光信息作为光度计。

图像中的EXIF数据会告诉您您可以累加以获得亮度的曝光值。有关详情，请参见 http://en.wikipedia.org/wiki/APEX_system 。 p>

Is there a way to use camera (web camera or phone camera) as a light meter? Phone camera can grab image and get data in RGB format, but has anyone tried to determine illuminance value (in lux)?

I am aware that there is no formula to do this (correct me if I am wrong), but is it possible to model it, and get an approximate value of illuminance?

解决方案

The problem you would have, as all reflective light meters do, is that you can't tell the difference between a bright light (high lux) shining on a dark object and a dim light (low lux) shining on a light object. In other words, you get luminance, not illumination.

The second problem is that you need to know the amplifier gain, exposure settings (f-stop, exposure time), transfer function (gamma), and other information to be able to get a correct photometric interpretation of the pixels in the image. If you have that information, though, you can just ignore the pixel data and just use the exposure information as a light meter.

The EXIF data in an image will tell you the exposure values which you can add up to get the luminance. See http://en.wikipedia.org/wiki/APEX_system for more details.

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