常见问题Frequently asked questions
关于隐私、水印写法、尺寸与打印的疑问，都在这里。Everything about privacy, watermark wording, sizes and printing.
这个网站会把我的图片上传到服务器吗？Will this website upload my images to a server?
不会。加水印、打码、导出全部在你的浏览器里用 Canvas 完成，图片不会离开你的设备，也没有任何上传请求。你可以断开网络后再试一次来验证。No. Watermarking, masking and export all run locally with Canvas in your browser, so your images never leave the device and no upload request is made. You can switch off your network to verify it.
我的图片会被保存下来吗？Are my images stored anywhere?
只保存在浏览器内存中，不写入服务器，也不写入 IndexedDB。刷新或关闭页面即消失；页面切到后台（切换标签页 / 最小化）持续 1 分钟会自动清空，30 分钟内没有任何操作同样会清空所有缓存内容，你也可以随时点「彻底清除」。They only live in browser memory — not on a server, not in IndexedDB. They disappear when you refresh or close the page; the page hidden in the background (tab switch / minimise) auto-clears after 1 minute, and 30 minutes of inactivity clears all cached content too, and you can press "Erase everything" at any time.
证件水印应该写什么内容？What should an ID-document watermark say?
建议写清「用途 + 限定 + 日期」，例如「仅供办理手机号实名使用 他用无效 2026-09-03」。避免只写「仅供参考」这类无效声明，也不要遮挡姓名、证件号、照片五官等关键信息。Use "purpose + restriction + date", for example "For mobile SIM verification only · void for other use · 2026-09-03". Avoid vague notes like "sample only", and never cover the name, ID number or your face.
水印加在什么位置最安全？Where is the safest place to put the watermark?
斜向平铺、以半透明方式压住证件空白处与背景，并让部分文字压到证件边框（但不遮挡关键信息）是最稳的：裁剪掉边角也会留下痕迹。A semi-transparent diagonal tile over the empty areas and background, letting some text cross the card border (without covering key data), works best: cropping the corners still leaves visible traces.
导出 PDF 和在线打印能保证实际尺寸吗？Do PDF export and printing keep real-world size?
能。导出按你设定的毫米尺寸计算，PDF 直接以毫米换算成磅值（1mm = 2.8346pt）。打印时请在打印对话框里选择「实际大小 / 无边距」并关闭「适合页面」，再用尺子核对一次即可。Yes. Exports use the millimetre size you set, and the PDF converts millimetres to points (1mm = 2.8346pt). In the print dialog pick "Actual size / no margins", turn off "Fit to page", then verify once with a ruler.
手机可以用吗？Can I use it on a phone?
可以。所有工具都做了移动端适配：支持相册选图、长按粘贴、双指滚动预览，面板在窄屏下会自动堆叠到画布下方。iOS 建议使用 Safari，Android 建议使用 Chrome。Yes. Every tool is responsive: pick from the gallery, long-press to paste, and the panels stack under the canvas on narrow screens. Use Safari on iOS and Chrome on Android.
支持哪些图片格式？大小有限制吗？Which image formats and sizes are supported?
JPG、PNG、WebP、BMP、GIF 等浏览器能解码的格式都可以，单文件不超过 40MB。超过 7000 像素的图片会自动等比降采样，以保证手机也能流畅处理。Any format your browser can decode — JPG, PNG, WebP, BMP, GIF — with a hard limit of 40MB per file. Images wider than 7000px are downsampled so phones stay smooth.
可以一次处理很多张图片吗？Can I process many images at once?
批量模式支持一次拖入多张图片，共用同一套水印参数，逐张下载或一键打包成 ZIP，也可导出成一份 PDF。Yes. Batch mode accepts many images at once, applies one shared watermark setup and lets you download files individually or as a ZIP, or export one combined PDF.
为什么导出 JPEG 后透明底变白？Why does the background turn white after exporting JPEG?
JPEG 不支持透明通道，导出时会按打印习惯自动铺一层白底。需要保留透明背景请使用 PNG。JPEG has no transparency, so a white background is applied on export (which is what printing wants). Use PNG when you need transparency.
水印字体的中文显示成方框怎么办？What if Chinese watermark glyphs render as boxes?
水印用的是你设备已安装的字体，因此导出结果与你系统里安装的字体一致。若某个字体缺少中文字形，切换到「系统默认」「黑体」或「宋体」即可。Watermarks use the fonts installed on your device, so exports match your system. If a font lacks Chinese glyphs, switch to System default, Hei or Song.
这个工具收费吗？会不会有水印角标？Is the tool free? Will you add your own logo?
完全免费，不注册、不限次数、不加任何官方角标或压缩。你可以自由用于个人和办公场景。Completely free: no sign-up, no limits, and no injected logo or extra compression. Use it for personal and office work.
身份证正反面怎么合成一页？How do I merge the front and back of an ID card onto one page?
在「图片加水印」工具里分别上传正面、反面两张图，各自加水印与打码后，选择「导出 PDF」即可把多张证件合并成一个文件。In the "Photo watermark" tool, upload the front and back as two images, watermark and mask each, then choose "Export PDF" to combine them into one file.