Compressing images without wrecking quality

Resize first when you can

A 4000px phone photo uploaded to a blog that displays at 1200px wastes bytes and often looks no better. Resize to the display width, then compress. Omnipus Image Resizer and Image Compressor are meant to be used in that order. Shrinking dimensions removes more weight than cranking a quality slider alone.

For email attachments, ask what the recipient needs. A receipt for reimbursement rarely needs a 12 megapixel original. A portfolio hero might. Match the compression to the job.

Pick a format on purpose

Photos: JPG or WebP with a quality slider around 0.7–0.85 is usually enough. Graphics with text or sharp edges: PNG or lossless WebP. Transparency: PNG/WebP — JPG will invent a background and ruin cutouts.

Watch the live preview. If type looks muddy, raise quality or switch format. Do not chase the smallest possible file if the subject is a product you sell. A blurry catalog image costs more than a few extra kilobytes.

Local compressors and their limits

Browser compressors re-encode on a canvas. They are great for web and email. They are not a substitute for specialized print RIPs or RAW workflows. Canvas export also typically drops camera EXIF, which is often desirable before sharing but worth knowing if you archive originals separately.

If a site asks you to upload photos to compress them, ask why. Compression does not require their disk — unless they are building a dataset or a funnel.

Batching tip: compress a representative image first and lock settings before running a whole set. Matching quality across a product gallery looks more professional than each photo hitting a different artifact level. Keep originals elsewhere so you can recompress later if a platform rejects the size.

Common mistakes

Recompressing an already heavily compressed JPG again and again multiplies artifacts. Start from the best master you have. Avoid upscaling a small image and then compressing — you spend bytes on invented blur. And do not use PNG for huge photos just because PNG sounds lossless; the file will balloon with little visual benefit over a careful JPG or WebP.

Finally, remember that perceived quality depends on display size. A 1200px image that looks crisp on a phone may show softness on a retina desktop. When the image is a hero above the fold, spend the extra kilobytes. When it is a thumbnail in a long list, compress aggressively. Match effort to how large and how long people will stare.