When you crop an image scaling it inside a dummy placeholder, the only variable that the system can use to accomplish this operation is to vary the DPI.

The crop area determine how many pixel from the image have to fit the final size (width or height).

Let's use few simple examples, where the crop marks an area width of 150 pixel and you want to print it in the box of following width:

•1 inch: the DPI of the output image will be 150 DPI.

•2 inches: the DPI of the output image will be 75 DPI

•A half inch box: the DPI of the output image will be 300 DPI,

Conclusion: it's not possible to scale a cropped image without changing its DPI value.