How images are placed on pages
For A4 (210 x 297 mm) and Letter (8.5 x 11 in) pages, each image is scaled to fit inside the printable area left after margins, keeping its aspect ratio and centring it. Small images are never enlarged beyond their natural size at 96 pixels per inch, which avoids blurry upscaling. In fit-to-image mode every page is sized to its picture plus the margin, which is ideal for screenshots and photos you will view on screen.
JPG files are embedded as-is without recompression, so they keep their original quality and the PDF stays compact. PNG files keep transparency. If the PDF is too large for email, run the images through the Image Compressor or Image Resizer first.