Digital Light & Color

The default in Warp is to produce an output image that is the same pixel size as the input image. If Warp is used to rotate/crop image (in ridgid mode) scale factor changes accordingly (which can be adjusted to near 1:1 with Scale slider).

Is there a way of keeping the scale factor to 1:1 without having to pay attention to it when doing cropping/level with Warp?

No there isn't -- but, as you probably know, you can do this using the Crop transformation instead.

The scale factor in Warp is computed as the ratio of the area of output image to the area of the cropping rectangle in the input image.

I added this feature in the latest (8.0.224) release.

Thanks for that!