Adobe 13102498 User Guide - Page 603

PHOTOSHOP CS3 596 User Guide Rendering plug-in name Entropy Kurtosis Maximum Mean Median Minimum Range Skewness Standard Deviation Summation Variance Result Comments entropy = - sum( (probability of value) * log2( prob- The binary entropy (or zero order entropy) defines ability of value) ) a lower bound on how many bits would be neces- sary to losslessly encode the information in a set. Probability of value = (number of occurrences of value) / (total number of non-transparent pixels) kurtosis = ( sum( (value - mean)4 ) over non-transparent 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). The maximum channel values for all non-transparent pixels The mean channel values for all non-transparent Effective for noise reduction pixels The median channel values for all non-transparent Effective for noise reduction and removal of pixels unwanted content from the image The minimum channel values for all non-transparent pixels Maximum minus the minimum of the non-transparent pixel values skewness = (sum( (value - mean)3 ) over non-trans- Skewness is a measure of symmetry or asymmetry parent pixels ) / ( ( number of non-transparent around the statistical mean pixels - 1 ) * (standard deviation)3 ) standard deviation = Square Root(variance) The sum channel values for all non-transparent pixels variance = (sum( (value-mean)2 ) over non-transparent pixels ) / ( number of non-transparent pixels - 1) 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.