Matching a size without losing quality

There are three ways to hit a target size, and each gives something up. Which one to pick depends on whether the original is bigger or smaller than the target, and whether margins are acceptable.

The three places quality goes

There are fewer ways to ruin a photo than people assume: scaling up, re-saving in a lossy format, and downscaling badly. Avoid those three and a photo survives any number of edits at its original sharpness.

1. Why scaling up softens

Going from 720x720 to 1080x1080 means inventing about 270,000 pixels that were never captured. The browser blends neighbours to fill them and edges smear in the process. Detail that was not recorded cannot be recovered by any method. AI upscalers invent plausible pixels; they do not restore what the camera never saw.

Filling a background leaves every original pixel untouched and adds new area around it. The photo itself is bit-for-bit unchanged. When you only need to satisfy a spec, this always wins. A 720x720 photo brought up to 1080x1080 this way gets 180px of background on each side, and the photo is exactly what it was.

2. Re-saving in a lossy format

JPG and WebP compress on every save, even at 100 percent quality. One pass is invisible; edit, save, reopen, edit again and artefacts pile up along letterforms and across smooth areas like sky. If a photo will be touched more than once, save the intermediate steps as PNG and export JPG only at the end.

3. Downscaling is safe, but method matters

Dropping a 6000px photo straight to 1080 makes fine lines and patterns look ragged. More than 30 source pixels collapse into each output pixel, and a naive resize looks at a few of them and discards the rest. Halving repeatedly is much cleaner. CropKit splits the reduction into steps automatically whenever the ratio exceeds 2x.

What "source quality" means

Pick a preset and the output is fixed at that pixel count. Save a 4000x3000 photo as Instagram 1080x1080 and it comes out at a quarter of the original width. Usually that is right — the app would scale it to 1080 anyway.

But if you plan to print it or crop it again later, not shrinking it is better. Source-quality export renders at whatever size keeps every original pixel used in the current edit. Crop the middle 2000x2000 out of a 4000x3000 photo and the result is 2000x2000. Nothing is scaled either way.

Format and quality

• For photographs, JPG at around 90 percent quality is the balance point. 100 percent nearly doubles the file size for a difference that is barely visible.
• For images with a lot of text or flat shapes, PNG is better. JPG leaves artefacts around letterforms.
• WebP is 20 to 30 percent smaller than JPG at matching quality, and it supports transparency, which makes it the best default for the web.
• If you need a transparent background, JPG is out. Transparency saves as white.
• Anything headed for a print shop or another editor should be PNG. It must not be compressed one more time on the way.