A watermark that stays readable on light and dark photos

2026-11-09

White text disappears into a bright sky. Black text disappears into a shadowy street. And a batch rarely contains only one kind of photo — there's always a beach shot next to a night shot. A watermark that only works on half of your images isn't doing its job, so it's worth knowing what our watermark tool does for you automatically and what is left to your choices.

The shadow you don't have to ask for

Every mark is drawn with a soft shadow in the opposite tone. White text gets a dark shadow (black at 45% strength); black text gets a light one (white at 45%). The shadow's blur is a fifth of the letter size, so it scales with the text instead of becoming a hairline on large marks or a smudge on small ones.

The effect is that the outline of every letter has some contrast against whatever is behind it. White text over a pale sky still reads, because each letter carries a faint dark halo; black text over a dark coat still reads, because of its light one. You don't switch this on — it's always there.

One consequence: opacity applies to the whole mark, shadow included. At very low opacity both fade together, and the readability boost fades with them.

Size follows each image's short side

The size setting is a percentage of the image's shorter side, not a fixed number of pixels. At the default 5%, a 6000 × 4000 photo gets text set at a font size of about 200 pixels, and a 1080 × 1080 image about 54 pixels. Both look the same relative to their picture.

That's what makes one setting work across a mixed batch. A fixed pixel size would be tiny on a camera original and enormous on a phone screenshot; a percentage of the short side also treats portrait and landscape photos alike. There's a floor of 10 pixels so the text never becomes unreadably small. The margin from the edges is proportional too — a little over half the font size.

The watermark tool lets you go from 2% to 15%; inside Batch edit the same control reaches 20%.

Picking white or black

There are two colours, and the choice is simpler than it looks:

• White for photos that are mostly mid-tone or dark — interiors, evenings, most outdoor scenes. With its dark shadow it also survives bright patches reasonably well.
• Black for photos that are mostly very bright — snow, white product backgrounds, scanned documents.

One colour applies to the whole batch. If your set is genuinely split between very bright and very dark images, run it twice — once for each group — rather than settling for a colour that half the photos fight against.

Placement and opacity on busy photos

Readability depends more on where the mark sits than on its colour. There are five positions: the four corners and the centre. Pick the one that lands on the calmest part of most photos — a plain wall or sky reads better than foliage or patterned fabric, whatever the colour.

Opacity starts at 55%, a middle ground. Raise it for busy backgrounds or when the goal is to deter reuse; lower it when the mark is a quiet signature and the photo is the point.

Check the result, not the settings

Text isn't shrunk to fit. A long handle at a large size on a narrow portrait image can run past the edge, especially in a corner position. After you type the text, flip through the results with the arrows above the preview — a few seconds per image catches the one photo where the mark sits on a face or runs off the side.

All of this runs in your browser; the photos are never uploaded.

What we deliberately don't do

The tool doesn't choose a colour per photo on its own. Guessing per image would make one batch come out with a mixture of white and black marks, and a watermark that changes from picture to picture looks less like a signature. You choose once; the shadow does the per-pixel work.

The short version

• Every mark gets an automatic opposite-tone shadow, so letters keep an edge on light and dark areas.
• Size is a percentage of each image's short side — one setting fits a mixed batch.
• White for mid-tone and dark photos, black for very bright ones; split the batch if it's truly mixed.
• Position on calm areas, then flip through the previews before saving.