Problem with pdf files

  1. I have some documents which have been recorded in pdf format
    When I open the pdf file the picture is very good

When I convert the pdf file to a Tif file with PDF Extract Tif software, I got a Tif file which is very light like surexposed and has lost details
(the result is the same even when I play with the settings)

For example:

This picture is a screen copy from the pdf file (I have lost some resolution already, which is normal, the pdf file been better)

This picture is a TIF one coming from the PDF to TIF converter
(you can see it is a lot lighter and I have lost details)
Furthermore it is impossible to play with brightness and so on )

  1. furthermore, when I put the 2 pictures here they look good both !!!
    Where is this coming from ?