Re: Measuring image contrast
- From: Chon-Ji <chonjiseed@xxxxxxxxx>
- Date: Mon, 13 Mar 2006 11:29:06 -0500
aslak grinsted wrote:
Hello is there a way to measure the contrast of an
The entire image or specific areas of the image?
I meant to include the following definition in my previous
The variation in the intensity of an image formed by an
system as black and white bars. Image contrast is defined
ofb)/(a + b), where a and b are the illuminance in the images
and dark bars respectively.
Is it possible to get the average contrast of the entire image?
is there a way I could relate contrast to the ambient luminance
we know that luminance could also affect the contrast in the
Basically, I need to test the performance of my system withrespect
to different levels luminance and contrast but not exactly surehow
to present them
I don't know if there is any well defined method. But it seems
you should measure some properties of the distribution of
in your image. I suggest the following measures:
* Median absolute deviation (of image converted to black and white)
as a measure for contrast. Alternatively use the normal standard
* Median as a measure of luminance.
* You could also check the skewness which may give some clues to
If saturated pixels is a common problem then you can try to make an
estimate of how many percent is affected by saturation and trim the
upper and lower x percentiles before analysis. You should keep the
constant though (or the measures wont be comparable between
Is there a way in matlab to compute for this media standard deviation?