Alpha

Transparent backgrounds for pixel sprites

A transparent sprite is a PNG whose empty cells have alpha 0. The checkerboard you see on the dark stage isn't in the file. It's the page showing through. Export small PNG, open it on a different background, and the subject should sit there with no box.

The sprite converter turns on "Drop the corner color" by default. After colors are chosen, it looks at the four corner cells. If at least two of them share a hex, every cell of that hex becomes empty. A product shot on a white sweep usually loses the white. A photo where the person's hair touches every corner loses the hair. Look before you download.

What the sampler does with alpha

If you upload a PNG that's already transparent, cells that are mostly clear stay clear. The average ignores pixels under 4% alpha, so a soft fringe doesn't tint the outline much. A heavily feathered cutout still leaves a dirty rim, because those pixels are partly opaque and they vote. Clean the rim with the brush: pick a swatch, paint, or select the fringe color in the legend and accept that you may repaint a few cells. There's no one-click "magic wand" beyond the corner drop.

JPG can't store transparency. If the original is a JPG, the white is real white pixels. Corner drop is the right tool, not a hope that the converter will guess the subject. SVG logos often already have empty space. They usually convert cleanly. GIF transparency depends on what the browser draws for frame one. If the GIF looks wrong, export a PNG from the app that made it and upload that.

Don't bake the checkerboard

Screenshotting the preview saves the checkerboard and the dark stage as ordinary pixels. You'll not get transparency back from that screenshot without keying it again. Use the Small PNG button. The large PNG also keeps alpha, which is handy for a slide with its own background. A grid, if you checked it, is drawn on top of the large file in the grid color. Those lines are opaque. Leave the grid off for a sprite you'll composite.

The export guide is blunt about this: the game wants the small file. A 32×32 PNG with alpha is the asset. A 400-pixel-wide preview is a picture of the asset.

A 32×32 check

Upload a logo or a photo on a plain background. Set width to 32. Confirm the meta line. Look at the four corners of the preview. If they are empty and the subject is intact, download small PNG. Drop that file into a doc with a red page color, or into the sprite slot of your engine. If you see a white or black box, the corners weren't removed. If you see holes in the subject, the corner color was also a shirt. Uncheck the option and paint only the backdrop cells. Painting is per cell, so a 32×32 backdrop is a one-minute job and it's more accurate than a tolerance slider that eats the outline.

Size and color still apply. Transparency doesn't make a 16×16 face readable. Pair this page with sprite sizes. And if the sprite is headed into a game with a fixed palette, snap colors before you paint, so you're not cleaning edges in colors the game can't display. The main converter has the same corner switch if you would rather start there and set 32 yourself.

Test the PNG on two backgrounds before you call it done: pure black and pure white. A dark fringe that vanished on the site's charcoal stage will show up on white. A pale fringe shows up on black. If you see a halo, those cells are semi-opaque leftovers from a soft cutout. Paint them to empty by choosing a problem color and overwriting the rim, or crop the source tighter and convert again. Two backgrounds catch more mistakes than staring at the checkerboard.

When corner drop is the wrong tool

Turn it off when the backdrop color appears in the subject: blonde on a yellow wall, white shirt on a white sweep. Paint empty cells by hand instead.

Sprite transparency checklist

Small PNG exported. Corners inspected on the preview. Subject intact on black and white backgrounds. Grid lines off for game use. Width matches engine slot. If anything fails, fix in the tab before you import. Re-importing a broken export doubles the work. See sprite sizes for readable silhouettes at tiny grids.

Questions

Keep going

• Sprite converter
• Sprite sizes
• Small PNG vs large PNG
• Main converter

Updated 30 September 2026