Constraint proportions in Image resize

System

Hi,

I use MB tasks to resize my images. Currently I am using the "Image Size" transformer to resize a bulk image to different sizes.
However , when I use "constraint proportions" , the image looks proper but it does not resize to the desired size.
Say, for eg,

I have a 934x526 dimension image. When I resize this to 494x248 image(with constraint proportions), it resizes to 440x248.

However , when i resize it , without using constraint proportions , it resizes to the actual size but the image is skewed/stretched.

Is there a workaround this ?