無損高壓縮比
先進演算法在肉眼無對差的前提下將圖片體積壓縮60～85%，網站載入與儲存成本大幅降低。
Type the size a form asks for and we hit it. Every file is re-encoded to land just under your target — same format, same dimensions — and when a target is physically out of reach we say so instead of quietly handing back something bigger.
We reach a target by lowering encoder quality, not by resizing or converting. That has a floor. A 200x230 ID photo holds 46,000 pixels; a 4000x3000 phone photo holds 12 million. The same 20KB target is trivial for the first and impossible for the second. When we hit that floor we return the smallest result we could produce and tell you the target was missed — we never silently shrink your dimensions or switch your format to fake a success.
Rule of thumb: the smaller the pixel dimensions, the smaller the target you can hit. If a target is out of reach, resize first and then come back.
Each page explains what is actually reachable at that target.
無需專業技術知識，免費快速的線上圖片處理工具，電腦手機全設備均可使用
我們在每個細節都做到極致，用技術保障每一次處理
Upload limits on exam portals, government forms and job applications are almost always written in kilobytes: photo under 50KB, signature between 10KB and 20KB, document under 200KB. Pixel dimensions are sometimes specified as well, but the KB limit is the one that rejects the submission. That is why people search for an image size reducer in KB rather than for an image compressor.
A KB limit is a hard constraint, not a preference. Either the file fits or the form refuses it. So the useful thing a tool can do is not just make the file smaller, but tell you plainly whether your target is reachable at all for the image you have — and what to change when it is not.
We do not resize your image and we do not convert it to a different format. The target is reached by binary-searching the encoder quality: we encode, measure, adjust and encode again until the result lands just under your number. Because this runs server-side with the real encoders (pngquant, cwebp, gifsicle, libjpeg) rather than a browser canvas, it keeps searching further down than an in-browser tool can before giving up. Target mode is available for JPG, PNG, WebP, GIF, HEIC, JXL, JP2 and JXR; other formats fall back to standard quality-based compression.