How to resize a photo without stretching it

You need a photo at an exact size, say 1080 × 1080, but your photo is a wide landscape. If you type both numbers into a careless tool, the picture squeezes into the square and everyone in it looks flattened. That distortion has a simple cause, and three honest ways around it.

Why stretching happens

Every photo has an aspect ratio: its width divided by its height. A landscape phone photo is usually 4:3, and a square is 1:1. As long as width and height scale by the same factor, the shape is untouched and nothing looks odd.

Halve both sides of a 4,000 × 3,000 photo and you get 2,000 × 1,500. The ratio is still 4:3. Now force that photo to 1,000 × 1,000, and the width shrinks to a quarter while the height shrinks to a third. The picture is squashed sideways. Circles become ovals and people look thin.

Resizing that keeps the shape

If you only care about size, and not about an exact shape, set one number and let the other follow. This never distorts.

• By longest side: 1,600 pixels means the larger side becomes 1,600 and the other adjusts.
• By width or height: fix one side and the other scales to match.
• By percentage: 50 percent halves both sides.

Longest side is a good habit for batches, because portrait and landscape photos both end up no bigger than the number you set.

When you need an exact shape

Sometimes the slot has a fixed shape: a square profile picture, a banner, a form that wants 600 × 800. The photo’s own shape does not match, so something has to give. There are three choices.

Crop to fill

Cut away the parts that do not fit and scale what remains to the exact size. Nothing is distorted, but you lose the edges. This suits portraits, profile pictures and anything where the subject is near the middle.

Fit with borders

Shrink the whole photo until it fits inside the frame and fill the leftover space with bars or a color. You keep everything, but the picture is smaller than the frame. This suits product shots, documents and group photos where cutting an edge would lose a person or a corner.

Stretch

Force the photo to the new size and accept the distortion. This is rarely what you want. It is only acceptable for abstract images, such as a texture, where no one can tell.

How the resizer maps to these

The image resizer offers five ways to measure, and they line up with the choices above:

• Longest side, width, height and percentage keep the shape. They are the “resize without changing the shape” case.
• Exact width and height is crop to fill. When the shape differs, it keeps the center of the photo, trims the edges and scales to the exact size. It never stretches.
• Fit with borders is not offered. If you need bars, make the photo fit by its longest side, then place it on a background in an editing app.
• Stretch is not offered either, on purpose.

Because the exact option always takes the center, it cannot choose the part you want. If the person is off to one side, they may be partly cut. In that case crop the photo in your gallery app first to the shape you want, then resize that.

Estimate how much gets cropped

Divide width by height for the photo and for the target. If the two numbers are close, cropping removes very little. A 4:3 photo going to a 1:1 square loses a quarter of its width. A 4:3 photo going to 16:9 loses part of the height. The more different the shapes, the more is trimmed.

Enlarging

Making a photo bigger adds pixels but no new detail. A small increase is fine. A big one looks soft. The resizer will not enlarge a photo until you tick the option for it, so you do not do it by accident. Photos can go up to 8,000 pixels on a side. Useful when a form sets a minimum size, but not a way to sharpen.

Keeping quality

Large photos are reduced in halving steps with smoothing at each one, which keeps fine patterns cleaner than one big jump. JPEG and WebP results are saved at 90 percent quality, and PNG is saved without loss. If the result must also fit a file size, run it through the compressor afterward. For the link between pixels and print sizes, see pixels, DPI and print size.

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