Ssim value range

The SSIM values ranges between 0 to 1, 1 means perfect match the reconstruct image with original one. Generally SSIM values 0.97, 0.98, 0.99 for good quallty recontruction techniques.

1. Should SSIM be high or low?
2. What does negative SSIM mean?
3. What is C1 and C2 in SSIM?
4. Why is SSIM better than MSE?

Should SSIM be high or low?

Complex Wavelet SSIM

is a small positive number used for the purposes of function stability. Ideally, it should be zero. Like the SSIM, the CW-SSIM has a maximum value of 1. The maximum value of 1 indicates that the two signals are perfectly structurally similar while a value of 0 indicates no structural similarity.

What does negative SSIM mean?

Because, if this is not the case then my similarity measure will cause problem (it results into values more than 1 when SSIM is negative, which means less similarity compared to the case of SSIM=0).

What is C1 and C2 in SSIM?

C1 = (0.01*L). ^2 , where L is the specified DynamicRange value. C2 = (0.03*L). ^2 , where L is the specified DynamicRange value.

Why is SSIM better than MSE?

MSE will calculate the mean square error between each pixels for the two images we are comparing. Whereas SSIM will do the opposite and look for similarities within pixels; i.e. if the pixels in the two images line up and or have similar pixel density values.