Clarify in documentation how input width/height and output width/height correlate about smartcrop.js

[valerian]

Thanks @mhulse for your very helpful explanation, this was indeed not obvious at all, and this is the only place where I found some clarification.

However it's still not completely clear: does that mean that the width and height from the options are only there to provide an aspect ratio of the desired crop? Multiplying or dividing them does not seem to affect the result at all.

From experimenting it seems that the minScale and maxScale options, when they have their 1.0 default value, make the crop result always have either 100% of the width or 100% of the height of the original image.
Lowering them allows smartcrop to also try to return potentially smaller crop sizes.

[jwagner]

Based on your input image size, and desired crop area, the resulting relative crop area is (width) and (height) at coordinates (x) and (y). You must crop your image using smartcrop's output width, height, x, y, and then scale up or down to your desired width and height (using tool of choice, like ImageMagick or GraphicsMagick).

This is correct. It seemed obvious to me but I guess it's not. I'll try to add some clarification in the next release. Thanks for sharing this.