🎚️ 图片位深度转换（1 / 2 / 4 / 8 / 16 位 PNG）Convert Image Bit Depth (1, 2, 4, 8 or 16-bit PNG)

使用说明与常见问题How-to & FAQ

「图片位深度转换（1 / 2 / 4 / 8 / 16 位 PNG）」是什么？What is the Convert Image Bit Depth (1, 2, 4, 8 or 16-bit PNG) tool?

把图片转换成指定位深度的 PNG：1 位黑白、2 / 4 / 8 位灰度、1 / 2 / 4 / 8 位调色板彩色，或 24 / 32 位真彩色、48 / 64 位（每通道 16 位）。输出文件真正按所选位深度存储，可选 Floyd–Steinberg 抖动减少色带，颜色本来就不多的图片会无损保留。适合嵌入式屏幕、电子墨水屏、打印和减小文件体积，图片只在浏览器本地处理。Convert an image to a PNG with the bit depth you choose: 1-bit black and white, 2, 4 or 8-bit greyscale, 1, 2, 4 or 8-bit palette colour, 24 or 32-bit true colour, or 48 or 64-bit (16 bits per channel). The file is genuinely stored at that depth, optional Floyd–Steinberg dithering reduces banding, and images that already have few enough colours are kept losslessly. Handy for embedded displays, e-ink screens, printing and smaller files — images are processed locally in your browser.

如何使用「图片位深度转换（1 / 2 / 4 / 8 / 16 位 PNG）」？How do I use the Convert Image Bit Depth (1, 2, 4, 8 or 16-bit PNG) tool?

在「图片位深度转换（1 / 2 / 4 / 8 / 16 位 PNG）」中，选择或拖入文件，按需设置「目标位深度」、「抖动」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 Convert Image Bit Depth (1, 2, 4, 8 or 16-bit PNG): Choose or drop your files, set "Target bit depth", "Dithering", then click the Download button next to each result (with several files, "Download all (ZIP)" saves them together).

位深度是什么？会影响画质吗？What is bit depth, and does it affect quality?

位深度是每个像素（或每个颜色通道）用多少位来存储：1 位只有黑白两种，4 位灰度有 16 级，8 位调色板最多 256 种颜色，24 位真彩色约 1678 万色。位深度越低文件越小、颜色越少，照片会出现色带或颗粒；图标、文字、线稿通常用低位深度也看不出差别。Bit depth is how many bits store each pixel (or each colour channel): 1-bit has only black and white, 4-bit greyscale has 16 levels, an 8-bit palette has up to 256 colours and 24-bit true colour has about 16.7 million. Lower depths give smaller files with fewer colours, so photos show banding or grain, while icons, text and line art usually look the same at low depths.

抖动有什么用？What does dithering do?

颜色或灰度级数很少时，抖动（Floyd–Steinberg 误差扩散）用相邻像素的点阵混合出中间色调，减少大块色带，看起来更接近原图；关闭抖动则每个像素直接取最接近的颜色，边缘更干净、文件通常更小，适合图标和像素画。With few colours or grey levels, Floyd–Steinberg dithering mixes neighbouring pixels to suggest in-between tones, reducing banding so the result looks closer to the original. Without it each pixel simply takes the nearest colour, giving cleaner edges and usually smaller files — better for icons and pixel art.

16 位输出能增加细节吗？透明怎么处理？Does 16-bit output add detail, and what about transparency?

不能。浏览器读出的图片是每通道 8 位，转成 48 / 64 位只是按标准把每个值放大（×257），适合需要 16 位文件的软件或流程，画面本身不会变。灰度和 RGB 模式没有透明通道，透明部分会填充为白色；32 / 64 位 RGBA 和调色板模式会保留透明。No. Browsers read images at 8 bits per channel, so 48 or 64-bit output just scales each value the standard way (×257) for software or workflows that need 16-bit files — the picture itself doesn't change. Greyscale and RGB modes have no alpha channel, so transparent areas are filled with white; 32 and 64-bit RGBA and the palette modes keep transparency.

支持哪些图片？会上传吗？Which images work, and are they uploaded?

支持 JPG、PNG、WebP、GIF（静态或动图的第一帧）、BMP、AVIF、HEIC，以及浏览器能打开的 SVG；可一次拖入最多 50 张批量处理，单张最大 60 MB、1 亿像素；多张结果可打包成 ZIP 下载。所有处理都在你的浏览器里完成，图片不会上传，结果中也不会保留 EXIF 等元数据（包括拍摄位置）。JPG, PNG, WebP, GIF (a still or the first frame of an animation), BMP, AVIF, HEIC, and SVG that the browser can open. Drop in up to 50 images at once; each can be up to 60 MB and 100 megapixels, and several results can be downloaded as a ZIP. Everything happens in your browser: images are not uploaded, and EXIF and other metadata (including location) is not kept in the results.

「图片位深度转换（1 / 2 / 4 / 8 / 16 位 PNG）」免费吗？需要注册吗？Is the Convert Image Bit Depth (1, 2, 4, 8 or 16-bit PNG) free? Do I need an account?

「图片位深度转换（1 / 2 / 4 / 8 / 16 位 PNG）」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 Convert Image Bit Depth (1, 2, 4, 8 or 16-bit PNG) is completely free with no sign-up or install and works on phones and desktops; what you enter is processed only in your browser.