↕️ 位图垂直翻转（上下颠倒 BMP）Flip a Bitmap Vertically
把位图（BMP）或其他图片上下翻转（垂直镜像）：最上面一行像素变成最下面一行，左右不变。逐像素精确，不会模糊或改变颜色。也可以用来修正因为行顺序（自下而上 / 自上而下）处理错误而上下颠倒的 BMP。默认导出 24 位 BMP，也可以导出 PNG，支持批量，图片只在浏览器本地处理。Flip a bitmap (BMP) or any other image upside down (a vertical mirror): the top row of pixels becomes the bottom row, and left and right stay put. It is exact pixel for pixel, with no blurring or colour change. It also fixes BMPs that come out upside down because some code got the row order (bottom-up versus top-down) wrong. The result is a 24-bit BMP by default, or PNG; works in bulk, and images are processed locally in your browser.
使用说明与常见问题How-to & FAQ
「位图垂直翻转（上下颠倒 BMP）」是什么？What is the Flip a Bitmap Vertically tool?
把位图（BMP）或其他图片上下翻转（垂直镜像）：最上面一行像素变成最下面一行，左右不变。逐像素精确，不会模糊或改变颜色。也可以用来修正因为行顺序（自下而上 / 自上而下）处理错误而上下颠倒的 BMP。默认导出 24 位 BMP，也可以导出 PNG，支持批量，图片只在浏览器本地处理。Flip a bitmap (BMP) or any other image upside down (a vertical mirror): the top row of pixels becomes the bottom row, and left and right stay put. It is exact pixel for pixel, with no blurring or colour change. It also fixes BMPs that come out upside down because some code got the row order (bottom-up versus top-down) wrong. The result is a 24-bit BMP by default, or PNG; works in bulk, and images are processed locally in your browser.
如何使用「位图垂直翻转（上下颠倒 BMP）」？How do I use the Flip a Bitmap Vertically tool?
在「位图垂直翻转（上下颠倒 BMP）」中，选择或拖入文件，按需设置「输出格式」等选项，然后点击每个结果旁的「下载」按钮即可；有多个文件时也可以点「全部下载（ZIP）」一次打包下载。In the Flip a Bitmap Vertically: Choose or drop your files, set "Format", then click the Download button next to each result (with several files, "Download all (ZIP)" saves them together).
翻转和旋转有什么区别？How is flipping different from rotating?
垂直翻转是上下镜像：图片里的文字会变成倒影一样的反字；旋转 180° 是上下、左右同时颠倒，文字只是倒过来而不是反字。垂直翻转再水平翻转就等于旋转 180°。A vertical flip mirrors top to bottom, so text looks like its reflection in water. Rotating by 180° turns the picture upside down and left to right at once, so text is upside down but not mirrored. A vertical flip followed by a horizontal flip equals a 180° rotation.
会损失画质吗？Is any quality lost?
不会。翻转只是重新排列像素，每个像素的颜色和透明度都原样保留，导出 BMP 或 PNG 都是无损的；翻转两次就得到和原图完全相同的图片。No. Flipping only rearranges pixels; every pixel keeps its exact colour and transparency, and BMP and PNG are both lossless, so flipping twice gives back an identical image.
导出的 BMP 是什么格式？What kind of BMP is produced?
默认导出 24 位不压缩 BMP（BITMAPINFOHEADER，自下而上存储），Windows 画图、Photoshop、GIMP、Python Pillow 和各种嵌入式工具都能直接打开。BMP 不支持透明，透明部分会填成白色并在结果里提示；需要保留透明请导出 PNG。By default a 24-bit uncompressed BMP (BITMAPINFOHEADER, stored bottom-up), which Windows Paint, Photoshop, GIMP, Python Pillow and embedded tools open directly. BMP has no transparency, so transparent areas are filled with white (the result says so); export PNG to keep transparency.
有哪些选项可以调整？What options can I adjust?
「位图垂直翻转（上下颠倒 BMP）」的设置：「输出格式」可选 BMP、PNG（默认 BMP）；可选文件：常见图片格式（含 HEIC、HEIF、AVIF、WEBP、BMP、JFIF）。改动任一选项后结果会按新设置重新生成。Settings in the Flip a Bitmap Vertically — "Format": BMP, PNG (default BMP); files: common image formats (including HEIC, HEIF, AVIF, WEBP, BMP, JFIF). Changing any option regenerates the result with the new setting.
图片会被上传到服务器吗？Are my images uploaded?
不会。「位图垂直翻转（上下颠倒 BMP）」使用浏览器 Canvas 在本地处理图片，处理后的文件直接从你的浏览器下载。No. The Flip a Bitmap Vertically processes images locally with the browser Canvas API and the result downloads straight from your browser.
「位图垂直翻转（上下颠倒 BMP）」免费吗？需要注册吗？Is the Flip a Bitmap Vertically free? Do I need an account?
「位图垂直翻转（上下颠倒 BMP）」完全免费，无需注册或安装，打开网页即可使用，手机和电脑都能用；输入的内容只在你的浏览器本地处理。The Flip a Bitmap Vertically is completely free with no sign-up or install and works on phones and desktops; what you enter is processed only in your browser.