📐 位图缩放（调整 BMP 尺寸）Resize a Bitmap

使用说明与常见问题How-to & FAQ

「位图缩放（调整 BMP 尺寸）」是什么？What is the Resize a Bitmap tool?

把位图（BMP）或其他图片缩放到指定尺寸：按像素填写宽度和/或高度（只填一个时按比例计算另一个），或按百分比缩放；可以锁定宽高比，也可以拉伸到精确尺寸。缩放方式可选“平滑”（高质量插值，适合照片）或“最近邻”（像素保持方块、边缘锐利，适合像素画、图标和单片机屏幕素材，按整数倍放大时完全不失真）。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。Resize a bitmap (BMP) or any other image: enter a width and/or height in pixels (fill in one and the other follows the aspect ratio) or scale by a percentage; keep the aspect ratio or stretch to an exact size. Choose Smooth (high-quality interpolation, for photos) or Nearest neighbour (pixels stay square with crisp edges — for pixel art, icons and microcontroller-screen assets; whole-number enlargements are perfectly lossless). 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「位图缩放（调整 BMP 尺寸）」？How do I use the Resize a Bitmap tool?

在「位图缩放（调整 BMP 尺寸）」中，选择或拖入文件，按需设置「单位」、「宽度」、「高度」、「缩放方式」、「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 Resize a Bitmap: Choose or drop your files, set "Units", "Width", "Height", "Method", "Format", then click the Download button next to each result (with several files, "Download all (ZIP)" saves them together).

“平滑”和“最近邻”怎么选？Smooth or nearest neighbour?

照片、截图缩小时选“平滑”，工具会分步高质量缩小，避免锯齿和摩尔纹；像素画、图标、游戏精灵、字体点阵等需要保持方块像素的图片选“最近邻”，每个输出像素直接取最近的原像素，不产生新颜色，放大 2 倍、3 倍等整数倍时完全不失真。For photos and screenshots choose Smooth: the image is reduced in high-quality steps to avoid jagged edges and moiré. For pixel art, icons, game sprites and bitmap fonts that must keep square pixels choose Nearest neighbour: each output pixel copies the nearest source pixel, no new colours appear, and enlarging by 2×, 3× and other whole numbers is perfectly lossless.

宽高比怎么处理？How is the aspect ratio handled?

只填宽度或只填高度时，另一边按原图比例自动计算。两个都填并勾选“保持宽高比”时，图片会缩放到能放进这个尺寸的最大大小（不变形）；取消勾选则拉伸到正好是填写的宽高。单位选“百分比”时，宽高按原图的百分比计算，适合批量处理尺寸不同的图片。Fill in only the width or only the height and the other side follows the original proportions. Fill in both with Keep aspect ratio and the image is scaled to the largest size that fits inside that box without distortion; untick it to stretch to exactly that width and height. In Percent units the values are percentages of the original size — handy for batches of different-sized images.

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?

「位图缩放（调整 BMP 尺寸）」的设置：「单位」可选 像素、百分比（默认 像素）；「宽度」可留空；「高度」可留空；「缩放方式」可选 平滑（照片）、最近邻（像素画）（默认 平滑（照片））；「输出格式」可选 BMP、PNG（默认 BMP）；可勾选：「保持宽高比」（默认勾选）；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 Resize a Bitmap — "Units": Pixels, Percent (default Pixels); "Width" optional; "Height" optional; "Method": Smooth (photos), Nearest neighbour (pixel art) (default Smooth (photos)); "Format": BMP, PNG (default BMP); tick boxes: "Keep aspect ratio" (on by default); 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。「位图缩放（调整 BMP 尺寸）」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 Resize a Bitmap processes images locally with the browser Canvas API and the result downloads straight from your browser.

「位图缩放（调整 BMP 尺寸）」免费吗？需要注册吗？Is the Resize a Bitmap free? Do I need an account?

「位图缩放（调整 BMP 尺寸）」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 Resize a Bitmap is completely free with no sign-up or install and works on phones and desktops; what you enter is processed only in your browser.