intensity measure has to be high or low for a good image

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chitresh
chitresh 2014-2-19
评论： chitresh 2014-2-22
Hi friends want to know few things about some parameters
1)(mean) the average intensity of the image has to be high or low for a better image?
2)(standard deviation)the spread of intensities across the image has to be high or low for a better image?
3) (skew) the asymmetry in the image’s intensity distribution has to be high or low for a better image?
4)(entropy) a measure of an image’s smoothness in terms of gray-level values has to be high or low for a better image?
5) (energy) the gray-level values are distributed within the image has to be high or low for a better image?
please guide me ... share some links which describe it has to be high or low ?
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chitresh
chitresh 2014-2-21
@David Young : better i mean quality, view, appearance.. if we compare two images then we can say one image is better because its mean, std, skew, entropy and energy is high or low ... hope you get my point
Image Analyst
Image Analyst 2014-2-21
Everyone understood that. We got your point, hence our answers, which remain unchanged despite your replies.

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回答（1 个）

Image Analyst
Image Analyst 2014-2-21
In general, for (1) the mean intensity should be higher for a better image. The more of your available dynamic range you are able to use, the better. For the others it really depends on what is causing the spread in gray levels - noise or the "true" subject. And it really depends on the subject. You can't give a blanket statement that covers all images that the image will be better or worse if those quantities are higher or lower. If you say one thing, you could easily think of an image that is a counterexample to that.
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Image Analyst
Image Analyst 2014-2-21
If you apply contrast stretching methods like you listed, the variation/spread in gray levels will be higher. That may or may not produce a more pleasing or more useful image.
I don't know of a paper that says more light is better. It's just common sense so people don't really write papers on that. You can search the web for it and perhaps find links such as "http://www.gcflearnfree.org/digitalphotography/3/print" that say "Generally, the more light you have, the better your photos will turn out. However, you'll also need to think about the quality of the light, as some types of light are more flattering than others"
If you want the technical reason, look up Poisson Noise and photons and photography. You could also look up shot noise and dark current.
chitresh
chitresh 2014-2-22
k thanks for the answer but may and may not still confusion not exact point...
k can we interpret image is better or worst through histogram reading if yes then please let me know how

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