Don't increase the DPI when compressing an image

[dly9014]

I see #197 was closed because changing the DPI is not the purpose of this library.

What we are seeing is that this library is actually increasing the DPI to 96 when images are compressed. This behavior seems like it is working against the maximum compression that can be achieved. If we can maintain the source DPI when it is less than 96 as part of the compression process, won't that make the corresponding file size smaller with no change in image quality?

[dly9014]

Possible to get an answer or some sort of status on this? Thanks in advance!