My logo is a transparent PNG; why does a color show behind it in the PDF, and how do I control it?

What keeping transparency means

PNG files go into Images to PDF as they are, alpha channel included. The transparent area around a logo does not turn white or black; it stays empty, so whatever is underneath on the page shows through. What is underneath is the background color you chose, or nothing if you switched the option off, in which case viewers normally show the page as white.

That is why a white logo on a transparent background can be a shock: on a white page it vanishes completely and the page looks blank, even though the logo is in the file.

Where the color setting is and what it paints

• The Colored page background checkbox starts switched on, with a Background color field next to it set to white.
• Click the color field and choose any color from your device's color picker.
• The color fills the whole page: the margins around the image, the empty space left by fit inside, and anything behind transparent parts of a PNG.
• JPEG images have no transparency, so their own background covers what is underneath and the page color only shows in the margins around them.
• Untick the checkbox and the color field disappears and no background is painted.

Which color suits your logo?

The rule is contrast with whatever sits behind it. A dark or colorful logo looks fine on the default white. A white or pale logo needs a dark background, such as your main brand color or a deep grey. If you have light and dark versions of the logo, use the dark one on white files.

Remember that the color applies to every page in the file. If the same PDF holds a white logo and a photographed document, a dark background will darken the document's margins too. In that case build two files or change one of the images.

When you want no transparency at all

Some recipients print on devices that handle transparency poorly, or simply want the logo on solid white. Convert the PNG to JPEG first with the Image format converter and choose the background color there; the transparent areas are filled with that color inside the image itself. After that, the page color no longer affects what is behind the logo.

A note about edges

Some PNG logos were designed on white and had the background removed afterwards, leaving semi transparent, pale pixels around the letters. On a white page you never notice, but on a dark background they show up as a thin halo around the logo. The fix is in the original design file, not in the PDF settings.