Adobe Photoshop CS3 User Manual
Page 603
PHOTOSHOP CS3
User Guide
596
Remove stack rendering
❖
Choose Layers > Smart Objects > Stack Mode > None to remove any rendering from an image stack and convert
it back to a regular Smart Object.
Edit an image stack
Because an image stack is a Smart Object, you can edit the original images that make up the stack layers at any time.
❖
Choose Layer > Smart Objects > Edit Contents, or double-click the layer thumbnail. After you save the edited
Smart Object, the stack is automatically rendered with the last rendering option applied to the stack.
Convert an image stack
To preserve rendering effects on an image stack, convert the Smart Object to a regular layer. (You may want to copy
the Smart Object before converting, in case you want to later re-render the image stack.)
❖
Choose Layer > Smart Objects > Rasterize.
Rendering plug-in name
Result
Comments
Entropy
entropy = - sum( (probability of value) * log2( prob-
ability of value) )
Probability of value = (number of occurrences of
value) / (total number of non-transparent pixels)
The binary entropy (or zero order entropy) defines
a lower bound on how many bits would be neces-
sary to losslessly encode the information in a set.
Kurtosis
kurtosis = ( sum( (value - mean)
4
) over non-trans-
parent pixels ) / ( ( number of non-transparent
pixels - 1 ) * (standard deviation)
4
).
A measure of peakedness or flatness compared to
a normal distribution. The kurtosis for a standard
normal distribution is 3.0. Kurtosis greater than 3
indicates a peaked distribution, and kurtosis less
than 3 indicates a flat distribution (compared to a
normal distribution).
Maximum
The maximum channel values for all non-trans-
parent pixels
Mean
The mean channel values for all non-transparent
pixels
Effective for noise reduction
Median
The median channel values for all non-transparent
pixels
Effective for noise reduction and removal of
unwanted content from the image
Minimum
The minimum channel values for all non-trans-
parent pixels
Range
Maximum minus the minimum of the non-trans-
parent pixel values
Skewness
skewness = (sum( (value - mean)
3
) over non-trans-
parent pixels ) / ( ( number of non-transparent
pixels - 1 ) * (standard deviation)
3
)
Skewness is a measure of symmetry or asymmetry
around the statistical mean
Standard Deviation
standard deviation = Square Root(variance)
Summation
The sum channel values for all non-transparent
pixels
Variance
variance = (sum( (value-mean)
2
) over non-trans-
parent pixels ) / ( number of non-transparent pixels
- 1)