pdfSetJPEGQuality
Set the JPEG quality level.
void pdfSetJPEGQuality(PDFHandle pdf, int quality)
This function sets the JPEG quality factor, which is a number from 0
to 100. 0 is the lowest quality and highest compression; 100 is the
highest quality and lowest compression. You will generally want to use
values in the 50-95 range. The default value is 75.
This parameter is only relevant when pdfWritePageBitmap or
pdfWriteRegionBitmap is called with pdfImageFileJPEG.
The pdfResetBitmapParams function resets JPEG quality to the
default value of 75.
C:
pdfSetJPEGQuality(pdf, 85);