2
$\begingroup$

I am using Emgu C#.

I acquire images from my cameras.

I know when there is no saturation (ie a grey-tone image) by looking at the average hue channel of the image. If zero then pretty sure picture taken at night time.

I can also detect how bright an image is by checking the average Luminescence channel.

What I would now like to do is a value for the gamma an contrast of an image.

Now, I know it is the interpretation of this hypothetical gamma and contrast that determines its value within the context of how I use it. But what factors can i use to attempt to put a scale on these values?

Should I be looking at a different Color Space?

Thanks

Improve this question
$\endgroup$
2
$\begingroup$

You should take a photograph of an object with known color values, such as Macbeth chart:

enter image description here

By using the lowest row of grayscale colors, you will be able to find out the tone-mapping (sometimes incorrectly called gamma) of your imaging system.

Improve this answer
$\endgroup$
2
  • $\begingroup$ Hi, interesting but how would I apply that to a live stream? I though that gamma is almost like contrast where it is 'highs' and 'lows' of an image that distinguishes its 'intensity'? Would this not server better as saturation correction. Of course, I may not have a clue what I am talking about $\endgroup$ – Andrew Simpson Jan 31 '15 at 16:28
  • 2
    $\begingroup$ en.wikipedia.org/wiki/Tone_mapping - this might clear things out $\endgroup$ – Andrey Rubshtein Jan 31 '15 at 17:19

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.