How to increase contrast of a topography map while converting ps2pdf while using transparency

Dear experts, I made a topography map for my research requirement and i used the transparency in order to see the background topography…while i convert ps to pdf by using the command gmt psconvert -A -P -Tj -S the pdf map doesnot retain original contrast however it fades away.Can anybody suggest how to retain the original contrst in pdf file or does it require to increase some dpi value.

I hope i will get some tips for solving this problem…

Without examples, hard to say anything.

As @Joaquim said – hard to tell without examples but I had a similar problem once and it boiled down to conversion between different color spaces. A directly displayed PostScript file has noticeably different colors than a PostScript file converted to PDF. Maybe have a look in this direction. Wikipedia on color space