Why are certain layers in my layered image being cropped? Why is white space not added with the Size command?
From the documentation:
The image is scaled to be no larger than "size=." If you specify a normalized size, it is relative to the size of layer 0. If you specify both width and height, the source image is scaled (after crop= is applied) so that neither dimension exceeds the specified size. The aspect ratio of the source rectangle is maintained in all cases.
Compare this command to the width and height commands, which fills the entire area:
If scl= is not specified, the composite image is scaled to fit. If both wid= and hei= are specified, and scl= is not specified, then the image is scaled to fit entirely within the wid/hei rectangle, leaving as little background area exposed as possible. In this case, the image is positioned within the view rectangle according to the align= attribute.
The result of this is that some unexpected cropping can occur if sizing is done on the image used in layer 0.