Z-Scores and Pearson Correlation: If we have scores that are expressed as standardized scores -- Z-Scores with a mean of zero and a variance of one -- then the formula for the Pearson Correlation becomes particularly simple.
PNG Formats. .PNG files in logo design and when you should use them. PNG is an acronym for Portable Network Graphics. PNGs are bitmpapped (raster/pixel based) image formats that can be used instead of GIF images or JPGs. PNG logo images are superior to other pixel based formats as they employ a âlosslessâ data compression system.
PNG files offer alpha transparency, meaning you can have areas of your images that are either fully transparent or even use a range of alpha transparency. For example, a drop shadow uses a range of transparency effects and would be suitable for a PNG (or you may just end us using CSS shadows instead).