In Settings on the PDF Configuration tab, select Files & Format > Output Options > Image Options

DPI value (dots per inch) A measure of screen and printer resolution that is expressed as the number of dots that a device can print or display per linear inch. 

resolution The fineness of detail attained by a printer or a monitor in producing an image. 

transparency In computer graphics the lack of color in a particular region of an image so that the background color of the display shows through. 

interpolate To estimate intermediate values between two known values in a sequence. 

scale To enlarge or reduce a graphic display, such as a drawing or a proportional character font, by adjusting its size proportionally. 

.bmp The filename extension that identifies raster graphics stored in bit map file format. 

.jpg The filename extension that identifies graphic images encoded in the JPEG File Interchange Format.