jpegQuality

Set the JPEG quality level.
[read/write property] jpegQuality([out, retval] int *quality) jpegQuality([in] int quality)
This property 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 writePageBitmap or writeRegionBitmap is called with imageFileJPEG.

The resetParams function resets JPEG quality to the default value of 75.

VB6:
pdf.jpegQuality = 85
resetParams
writePageBitmap
writeRegionBitmap