+\qquad W Ratio = $\frac{W_f}{W_i}$ \qquad H Ratio = $\frac{H_f}{H_i}$
+
+with $W_f$/$H_f$: final Width and Height; $W_i$/$H_i$: initial Width and Height.
+
+The new canvas size is recalculated based upon a certain factor in the \texttt{W Ratio}, \texttt{H Ratio} fields. A practical use-case: the current resolution is $640 \times 480$, and for some reason you want Width to be 1.33 times bigger. You don't have to calculate what $640 \times1.33$ is; you type 1.33 into the \texttt{Width} input instead, and \CGG{} calculates it for you. W/H Ratio works as a local calculator. Warning: if you vary W/H Ratio without adjusting Display aspect ratio, we may get non-square pixels resulting in anamorphic frame distortion.
+
+\item[Display aspect ratio:] \index{aspect ratio} sets the aspect ratio; this aspect ratio refers to the display aspect ratio (DAR). The aspect ratio is applied to the video output (canvas). It can be convenient to vary the size of the canvas in percentage terms, instead of having to calculate the number of Width x Height pixels. The aspect ratio can be different than the ratio that results from the formula: $\dfrac{h}{v}$ (the number of horizontal pixels divided into the number of vertical pixels). If the aspect ratio differs from the results of the formula above, your output will be in non-square pixels.
+
+\item[Auto aspect ratio:] if this option is checked, the \texttt{Set Format}