How to make PDF v1.6 files comprisable in LaTeX?

 This issue may concern when you are using TeX Live distribution of dvipdfmx.

It is a common problem that PDF v1.6 files are not comprisable in LaTeX sources to produce PDF outputs using dvipdfmx. This problem occurs due to a line at the beginning of a file dvipdfmx.cfg that reads

V 5

which specify the output PDF version to be 1.5. The problem is fixed by just replacing this line by

V 6

The file dvipdfmx.cfg is placed in <distribution>/texlive/<version>/texmf-config/dvipdfmx for typical cases of TeX Live distributions.

I encountered this problem in TeXShop with ptex2pdf for Japanese writing and found the file in the directory with <distribution> = /usr/local and <version> = 2013.