# ProShow/Photopia Equations

Photodex is not exactly forthcoming about some of the inner workings of its star Programs Gold and Producer. But then too, the same thing applies to Photopia. They normalize imported graphics and images and do not tell you how it is done. You have to figure it out on your own. Generally, this involves figuring out how tall or wide the layer is for a specific size.

To make effective use of rotate center, you generally must do some math. From ProShow v4 through v9 and Photopia v1, only a layer-centric rotation center feature is provided. Any rotate/tilt of a layer around a user defined location requires some calculations on your part. If you have no idea how the program does what it does or even where the rotation center values come from, you are looking at a significant expenditure of time and energy to get the rotation point desired.

I am one of a very few who have figured out some of ProShow’s/Photopia’s mysteries, capabilities to which Photodex/Photopia has not directly provided access. I figured out many of them. With respect to rotate center I figured them out and have provided them below. Hopefully you may find them of use. ProShow introduced the Rotate Center in Spring 2010 and to date, the function remains unchanged. I discovered how to make effective use of Rotate Center in June 2011 and originally published my findings around September 2011. You can use the equations given below to develop your own calculation tools or use the one’s I’ve developed here.

These equations deal with Pan, Zoom, Rotation Center, Width, and Height in all ProShow/Photopia Scales. Note that Stretch to Frame effectively converts the layer’s height and width to the screen aspect (and so is not directly referenced). Enjoy … and, Good Luck!

ProShow-Photopia Equations 2018 update 200707

Update
Fixed minor errors with Safe Zone Equations. Adjusted all equations to use a decimal number representation of the Zoom percent value rather than the decimal value of zoom. Therefore, a zoom of 60% is represented as 60 for the value of Z instead of 0.60. This should make it easier to use and understand the equations. This also improves the consistency in how numbers are represented in the equations. Finally, simplified the presentation of the equations.

Update (201805). Added additional relationships. Made some equation simplifications related to Safe Zones. The Zoom value is now assumed as the decimal representation versus the percent representation. The Pan Value is now given as the Effective Pan value.

Update (20181020). Corrected equations to adjust for the fact that zoom values are decimal. This was inadvertently overlooked.