Image Compression FAQ

Q: Will image quality degrade after compression?

It depends on how hard you compress. Moderate compression (70-85% quality) is barely noticeable to the naked eye, but pushing below 50% introduces color banding, blur, and jagged edges. TinyPNG and Squoosh both use conservative defaults — you won't ruin anything under normal use. Sure, if you zoom in 500% and pixel-peep, you'll see losses — but who looks at images at 500% magnification in real life?

Q: Are online compression tools safe? Will my images be stored?

TinyPNG officially states they delete your images after processing — as a well-known company, they're unlikely to trash their reputation over this. However, if you're uploading sensitive documents like IDs or contracts, use a local tool (Caesium, ImageOptim) or Squoosh — Squoosh does all processing inside your browser, nothing gets uploaded. Rule of thumb: non-sensitive images are fine with online tools; sensitive ones should stay local.

Q: What's the difference between lossless and lossy compression?

Simply put: Lossless = 100% quality preserved, file size reduced by optimizing encoding structure — typical compression ratio 20-40%. Lossy = sacrifices some imperceptible detail for much greater compression — typically 60-80%. For everyday use (websites, social media), lossy is fine — you won't notice the difference on a phone screen. Use lossless for archiving originals.

Q: Which compresses better — JPEG or PNG?

JPEG is inherently a lossy format, designed for compression from the start, so there's less headroom (it's already compressed). PNG is lossless — it's common to compress a 2MB screenshot down to 300KB, so the potential is huge. Simple rule: photos → JPEG, screenshots/logos/icons → PNG (then compress them).

Q: How do I compress hundreds of images at once?

Use Caesium (cross-platform desktop app). Drag your folder in → set parameters → hit start. It processes in multiple threads, handling hundreds of images in minutes. Don't use online tools for this — uploading one by one is painfully slow and most have per-batch limits. See the Guide for detailed steps.

Q: Can I restore the original image after compression?

Lossy compression = irreversible. Once compressed, there's no going back. So keep a backup of your originals before compressing (hard drives are cheap). Lossless compression is theoretically reversible, but in practice most tools also strip metadata, and that's gone for good. Bottom line: always back up your originals before compressing.

Q: Why did my PNG get bigger after compression?

It's rare but it can happen. Possible reasons: the original was already aggressively compressed, or your compression settings are weaker than the original's. Try a different tool, or convert to another format first. For example, if a PNG is too large, convert it to WebP — WebP compression is much more efficient than PNG.

Q: Are mobile image compression apps reliable?

There are image compression apps for both iOS and Android, but quality varies wildly. Many have poor compression, are stuffed with ads, and some even secretly upload your images. If you need to compress on mobile, I recommend opening Squoosh.app in your browser (it supports PWA and works offline). Way more reliable than those sketchy apps.

Q: Does image compression help with SEO?

Absolutely. Google uses page load speed as a ranking factor, and images typically account for 60%+ of a page's total size. After compression: pages load faster → lower bounce rates → better Core Web Vitals scores → higher rankings. Google's PageSpeed Insights will even flag which images need compression. Doing SEO without compressing images is like running in flip-flops — you can do it, but it's not comfortable.