Auto image square trimmer

The smallest square that holds the whole subject

An app icon, an avatar, a favicon, a product in a shop’s grid: all of them ask for a square, and most pictures are not one. Cropping a square by hand cuts into the subject or leaves it small in a corner. Here the subject itself decides the square.

• The empty space around the subject, transparent or of one plain color, is found on every side, exactly as the auto image trimmer finds it.
• The square’s side is the subject’s longer side: a wide subject touches the left and right edges, a tall one the top and the bottom.
• On the other two sides it is centered, with the same space on each.

So the subject is as large as a square can show it. Nothing of it is cut, and nothing is stretched or resampled.

Where the square is made of new background

A wide logo in a short picture has no room above and below it for a square. The missing bands are made of the picture’s own background: transparency stays transparent, a plain color is continued in that same color.

A margin, in pixels or as a share of the subject’s longer side, adds the same room on all four sides; the result is still a square.

A set of pictures that sit alike

Trimmed this way, logos or products all behave the same in a grid: each fills its square from edge to edge on its longer side and is centered on the other, whatever empty space its file carried. Drop as many as you like: each is read with the same settings and its own background, and they download together as a ZIP.

The tolerance says how far from the background a pixel must be to count as subject: the starting value, 4%, reads through the noise of a JPG and keeps a soft shadow on transparency whole, and a higher one cuts faint shadows as well. On a scan, “Ignore specks” keeps a dot of dust from holding the square open.

What comes out

The file keeps its format when your browser can write it (PNG, JPG, WebP, AVIF). Its side in pixels is the subject’s longer side, plus the margin if you set one. A JPG, a WebP or an AVIF is written again at high quality; choose PNG to stop the loss there. What the camera wrote into the file (place, date, device) is not carried over.

To choose by hand which part of a photo a square keeps, use the square crop; to change a picture’s format, the image converter.