moderncv - filesize of pdf too big

There is no package makemypdfsmaller.sty which reduces the PDF file size without removing information. However, there are a few things you can do:

Reduce number of images

Do you really need to include eighteen images? Maybe sixteen or twelve is enough.

Reduce image size

You can use imagemagick (or gimp or …) to reduce the image size. You have to experiment which values are acceptable.

convert -geometry 75% input.png output.png

Reduce amount of colours

Especially when the image contains text on white background or just a few colours, like certificates often do, you can significantly reduce the image size. Try different values, e.g. 4, 8, 16

convert -colors 16 input.png output.png

Run optipng on the file

The program optipng can shrink the file about one to four percent more after you have reduced the amount of colours. Not much, but it's lossless. The slowest setting with the highest compression is -o7.

optipng -o7 input.png

Increase PDF compression

Set \pdfcompresslevel9. This also does not help much, but maybe it helps to squeeze it just enough to fit into a file size limit.

Reducing the final PDF

When you already created the PDF or you don't have access to the images any more, you can use ghostscript to reduce the resolution of the final PDF. Use for instance the setting -dPDFSETTINGS=/ebook. Here is an example.

gs \
  -sOutputFile=output_file.pdf    \
  -sDEVICE=pdfwrite               \
  -dNOPAUSE                       \
  -dBATCH                         \
  -dPDFSETTINGS=/ebook            \
  input_file.pdf

/ebook sets the resolution to 150 DPI. Other settings are /screen (75 DPI) or /print (300 DPI).