||Include Images as JPEG: When checked, PStill will compress raster (gray and color) images using the JPEG compression method, resulting in much smaller output files with some loss of image quality. You can set the quality level with the slider: slide to the left for lower quality/higher compression and to the right for higher quality/lower compression.|
Downsample Images: If checked, then images are downsampled to the DPI in the fields. One field is for color or grayscale images and the other is for monochrome images.
Typically, if you’re creating PDF for the web, you want 72 dpi for color, and 150 dpi for B&W.
If you’re creating PDF for standard printers, 300 DPI is usually adequate.
For lossless preservation of image quality, uncheck "Downsample Images".
Images can be included as compressed JPEG's with or without downsampling.