JPG vs PNG vs WebP for merged images

Updated 15 June 2026

Once you've combined your photos, the format you save in decides two things: how sharp the result looks and how big the file is. Most people never think about it and just accept whatever they're given — but for merged images, the choice genuinely matters, especially where two photos meet. Here's a plain-English breakdown of JPG, PNG, and WebP so you can pick the right one.

The 30-second answer

• PNG — lossless and pixel-perfect. Best for screenshots, text, sharp edges, and anything you'll edit again. Larger files. This is what StitchPic exports.
• JPG — small files, great for photographs, but it's lossy and can smudge crisp edges and seams. No transparency.
• WebP — modern format that's smaller than both at similar quality, supports transparency, and is ideal for the web. Slightly less universal in old software.

How they actually differ

Why merged images are a special case

When you stitch two images together, you create a hard seam where they meet — often a sharp transition between very different colours. JPG's lossy compression struggles exactly at high-contrast edges, producing faint “mosquito noise” or blocky artefacts around the seam and any text. That's why StitchPic exports a PNG: it keeps the seam clean and every pixel intact, which matters most for screenshots, diagrams, and side-by-side comparisons.

When you should convert to something smaller

PNG is the safe master copy, but it can be heavy. Convert after merging if:

• It's a photo collage with no text and the PNG is several megabytes — a high-quality JPG (around 80–90% quality) will look nearly identical at a fraction of the size.
• You're publishing to the web — WebP gives you the smallest file with excellent quality and is supported by all current browsers.
• A platform has an upload limit — compress the PNG to JPG or WebP to fit under it.

Keep the original PNG as your archive copy and make smaller versions from it as needed — never re-compress a JPG into another JPG, as quality drops each time.

A simple rule of thumb

Merge and export as PNG (the default). If the file is too big and the image is mostly photographic with no fine text, make a JPG or WebP copy for sharing. If it has screenshots, diagrams, or crisp edges, keep the PNG.