Are you really using Gimp 2.8? For any version of Gimp.
Gimp by default will open a PDF with a resolution of 100 ppi.
Open the PDF with a resolution of 300 ppi, which is commonly equated to photo quality.
Sceenshot of what to look for here: https://www.gimp-forum.net/Thread-PDF-fi...6#pid13176
Of course still depends on the PDF. If a low quality image is embedded then no amount of adjustment will improve it.
edit: You know, posting the same question on multiple sites does not really improve your chances of getting an answer, especially a question that has been asked before. A search might have got you an answer straight away.
Gimp by default will open a PDF with a resolution of 100 ppi.
Open the PDF with a resolution of 300 ppi, which is commonly equated to photo quality.
Sceenshot of what to look for here: https://www.gimp-forum.net/Thread-PDF-fi...6#pid13176
Of course still depends on the PDF. If a low quality image is embedded then no amount of adjustment will improve it.
edit: You know, posting the same question on multiple sites does not really improve your chances of getting an answer, especially a question that has been asked before. A search might have got you an answer straight away.