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。
50KB is the most common photo limit on exam registration and government forms. A photo already at the dimensions the form asks for reaches it comfortably. A full-resolution phone photo usually does not.
The dividing line sits around a million pixels. Images up to roughly 800x1000 reach 50KB at a quality that still looks fine on screen. Above that, quality starts to visibly degrade before the file fits, and past about 3000x2000 the target usually cannot be reached at all. If your form also specifies dimensions, resizing to them first solves both requirements at once.
If the form gives you both a KB limit and a pixel size, do the pixel size first. It is the step that makes the KB limit reachable.
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50KB is large enough to hold a recognisable face at passport dimensions and small enough that a portal handling millions of applications does not run out of storage. That balance is why the same number appears again and again across otherwise unrelated systems: exam boards, provident fund portals, PAN and Aadhaar services, university admissions.
Because the limit is tied to a specific document type, it comes with an implied dimension. A form asking for a 50KB photo almost always also names a pixel or millimetre size. Meeting the dimension first is not extra work, it is the shortcut: at the right dimensions, 50KB stops being a squeeze.
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.