Compression
How to compress images without losing quality
There are two ways to shrink an image, and only one of them touches quality you can actually see. Here is how to get much smaller files that still look identical.
Last updated July 23, 2026
What “without losing quality” actually means
Almost every image can be made dramatically smaller with no visible change — the catch is that “no visible change” and “not a single byte altered” are two different promises. Understanding which one you need is the whole game.
| Type | What it changes | Size drop | Looks the same? |
|---|---|---|---|
| Lossless | Nothing in the pixels — only how they’re stored | Small to moderate | Pixel-for-pixel identical |
| Lossy (visually lossless) | Removes detail the eye can’t detect | Large | Identical to your eye, not to a diff tool |
Lossless: same pixels, tighter packaging
Lossless compression rewrites the file more efficiently without altering a single pixel. A PNG saved straight out of a design tool often carries redundant data; re-optimizing it (the job a tool like OxiPNG does) can shave 10–20% with a guarantee that the image is byte-for-byte identical when decoded.
It’s the right choice when exactness matters — a logo with flat colors, a screenshot with text, a diagram, or anything you might edit again later. The downside: on a detailed photograph there’s little redundancy to remove, so lossless alone rarely gets you a big win.
Lossy, but invisible: where the real savings live
This is the part most people miss. A full-color PNG stores up to 16 million possible colors per pixel — far more than your eye can distinguish in a single image. Color quantization reduces that to a carefully chosen palette (up to 256 colors) and adds subtle dithering, and for most images the result is indistinguishable from the original while being 40–70% smaller.
This is exactly the technique behind popular “tiny” PNG compressors. It’s technically lossy, but tuned so the loss falls below what human vision can pick up. For photographs and rich illustrations, it’s almost always the setting you want.
How to compress in your browser
You don’t need to upload anything to a server to do this. Drop your images into the browser-based compressor and it applies smart lossy compression by default — the same quantization described above — so you get the big size drop automatically. Everything runs on your device.
If you need the exact-pixels guarantee, flip on the Lossless toggle. Ruah hides the quality slider for PNG on purpose: instead of making you guess a number, it gives you the two choices that actually matter — smallest-but-invisible, or perfectly exact.
When to choose lossless anyway
Reach for the Lossless toggle when:
- The image is a logo, icon, or line art with a few flat colors — these are already tiny and lose nothing, so there’s no reason to quantize.
- You have smooth gradients (a sky, a soft shadow) where 256 colors could introduce faint banding.
- The file will be edited further and you don’t want to stack compression passes.
For everything else — photos, screenshots of real scenes, detailed artwork — the default lossy mode gives you a much smaller file that looks the same.
One more free win: strip the metadata
Photos often carry hidden EXIF data — camera model, settings, even GPS coordinates. Removing it shrinks the file a little and, more importantly, protects your privacy. You can do that losslessly with the metadata remover, no re-encoding required.
Try it now — Compress in your browser, nothing uploaded.