{"slug":"sky-banding-solutions","title":"照片天空有奇怪色带？后期色彩断层的预防和解决方法 (视频教程)","author":"Thomas看看世界","date":"2021-10-03","wechat":"https://mp.weixin.qq.com/s?__biz=MzI4NDA5MzE5NQ==&mid=2247494032&idx=1&sn=903d64b6b64223db9c41b56feb82a627&chksm=eb8217f4dcf59ee2ff0e4d2a22fe972de8290663520ce6fc6c7884c975a5c3ec56ee87112a74&scene=21#wechat_redirect","blocks":[{"t":"h","x":"Thomas看看世界","xe":"Thomas Chu Photo"},{"t":"p","x":"色彩断层在人像拍摄（纯色背景）和风光后期（渐变天空）中都经常发生，明明应该细腻的颜色，却变成了一块一块的奇怪色带，简直让人崩溃。","b":false,"xe":"Color banding happens often in portrait shooting (solid-color backdrops) and landscape post-processing (gradient skies): what should be silky color turns into strange, blocky bands — enough to drive you mad."},{"t":"p","x":"本视频将在文章《不要让色彩断层毁了你的照片》的基础上，进一步谈谈色彩断层的成因，4种非常容易产生色彩断层的后期操作，以及2种弱化色彩断层现象的后期技术。","b":false,"xe":"Building on the article \"Don't Let Color Banding Ruin Your Photos,\" this video goes further into the causes of banding, the 4 post-processing operations most likely to produce it, and 2 techniques for minimizing it."},{"t":"h","x":"视频教程","xe":"Video Tutorial"},{"t":"bili","bv":"BV1Lv411G7Tt","bpic":"bili-1","bt":"不要让色彩断层毁了你的照片! 摄影后期色阶断带的避免和处理~"},{"t":"p","x":"这一篇是上面视频的图文整理版。Thomas 把 11 分钟口播里的内容全部落成文字，并配上视频关键帧截图：什么是色彩断层、为什么渐变天空最容易出现色带、四种极易引发断层的后期操作（8-bit 编辑、HSL 大幅度调整、降噪、动感模糊），以及两种原理性解法——提高色彩深度与仿色，最后手把手演示「50% 灰叠加图层 + 添加杂点」的救急流程。","xe":"This is the illustrated companion to the video above. Thomas turned the 11-minute walkthrough into text and paired it with keyframe screenshots: what color banding is, why gradient skies suffer most, four post-processing moves that easily trigger banding (8-bit editing, heavy HSL adjustments, noise reduction, and motion blur), plus two fundamental fixes — higher bit depth and dithering — ending with a hands-on \"50% gray overlay layer + Add Noise\" rescue workflow."},{"t":"img","f":"v01","w":852,"h":480},{"t":"p","x":"先看总览。上面这张要点页截自视频 2:14 处，列出了四种极易产生色彩断层的后期操作——在 8-bit 环境下进行后期、HSL 大幅度调整、降噪和动感模糊。下文先讲清断层的成因，再逐一展开这四条红线和对应的解决方案。","xe":"Start with the overview: this summary slide, captured at 2:14 in the video, lists the four post-processing moves most likely to cause banding — editing in 8-bit, heavy HSL adjustments, noise reduction, and motion blur. Below, we first unpack what banding actually is, then go through these four red lines and their fixes one by one."},{"t":"h","x":"01 什么是色彩断层","xe":"01 What Is Color Banding"},{"t":"p","x":"自然界的色彩是连续而细腻的，但电脑显示的颜色有数量限制。常用的 8-bit 图像每个通道只有 2 的 8 次方，也就是 256 种亮度等级——颜色不够用时，本该平滑的渐变只能「一级一级」往下跳，形成一条一条肉眼可见的色带。这正是日出日落、蓝调时刻的天空照片里最常见的崩溃现场（视频 0:29 处）。","xe":"Colors in nature are continuous and subtle, but a computer can only display a limited number of them. A common 8-bit image holds just 2 to the 8th power — 256 levels — per channel. When the colors run out, what should be a smooth gradient steps down level by level, producing visible bands. It is the classic heartbreak in sunset and blue-hour sky photos (at 0:29 in the video)."},{"t":"img","f":"v02","w":852,"h":480},{"t":"p","x":"上面 0:45 处的对比卡非常直观：同样的红色渐变，8-bit 版本已经断成一圈一圈的同心色带，而 24-bit 版本依旧平滑。色彩断层并不是所有照片都会有，它最爱出现在「大块的纯色渐变区域」：一是冷暖或明暗过渡的渐变天空；二是看起来纯色、实际带着微弱明暗变化的整片天空；三是 ND 镜长曝光或动感模糊雾化后的水面——面积大、颜色统一、又带渐变，三条全中（视频 1:00-2:00 处）。","xe":"The comparison card at 0:45 makes it instantly clear: in the same red gradient, the 8-bit version breaks into concentric rings while the 24-bit version stays smooth. Banding does not threaten every photo — it targets \"large areas of near-pure gradient color\": gradient skies transitioning between warm and cool or bright and dark; whole skies that look flat but carry subtle brightness shifts; and water turned to mist by ND long exposures or motion blur — large, uniform, and gradated, hitting all three criteria (at 1:00-2:00 in the video)."},{"t":"h","x":"02 四种极易产生断层的操作","xe":"02 Four Moves That Trigger Banding"},{"t":"p","x":"第一条红线，是在 8-bit 环境下做后期。从 Camera Raw 或 Lightroom 进入 PS 之前，一定要在底部的工作流程设置里把色彩深度选成 16 位（视频 2:14 处）；判断当前文件是几位的，看标题栏文件名后面 RGB 右边的数字——RGB/8 就是 8 位，RGB/16 才是 16 位。即使编辑的是一张 8-bit 的 JPG，也要在 PS 里通过「图像 → 模式」先转成 16 位再动手，编辑时产生的色带和断层会明显更少（视频 2:55-3:06 处）。","xe":"The first red line is editing in an 8-bit environment. Before entering Photoshop from Camera Raw or Lightroom, set the color depth to 16 bits/ channel in the workflow options at the bottom (at 2:14 in the video). To check the current file, look at the number right of RGB after the filename in the title bar — RGB/8 means 8-bit, RGB/16 means 16-bit. Even when editing an 8-bit JPG, convert it via Image → Mode → 16 Bits/Channel first; editing then produces far fewer bands (at 2:55-3:06 in the video)."},{"t":"img","f":"v03","w":852,"h":480},{"t":"p","x":"第二条红线是 HSL 的大幅度调整。以一张晚霞渐变天空为例：想把某块红色加强，如果在 HSL 里把红色饱和度拉到 100，天空立刻出现非常夸张、非常突兀的色带（视频 3:50 处，上面 3:52 的截图中水面倒影部分已经被拉出一团红色断层）。","xe":"The second red line is large HSL moves. Take a sunset gradient sky: if you push red saturation to 100 in the HSL panel, brutal, jarring bands appear immediately (at 3:50 in the video — in the 3:52 screenshot above, the reflection in the water already shows a blotch of red banding)."},{"t":"img","f":"v04","w":852,"h":480},{"t":"p","x":"正确的做法是换工具：用径向滤镜框住想提亮的区域，把饱和度整体提高（视频 4:07 处），或者用局部处理工具、选区套索把这块单独选出来再做整体饱和度提升。这样红色、橙色、黄色以及周边过渡的紫色会同时提升，渐变过渡保持完整，而不是只突兀地拉红一个通道（视频 4:15-4:33 处）。","xe":"The right move is to switch tools: frame the area with a Radial Filter and raise its overall saturation (at 4:07 in the video), or select it with a local adjustment tool or the lasso before boosting saturation. That way red, orange, yellow and the surrounding transitional purples rise together, keeping the gradient intact instead of yanking one channel alone (at 4:15-4:33 in the video)."},{"t":"img","f":"v05","w":852,"h":480},{"t":"p","x":"第三条红线最反直觉：降噪。照片里如果有纯色天空，降噪反而可能帮倒忙。案例这张照片 100% 放大时天空噪点明显，于是在 Camera Raw 滤镜里把「细节 → 减少杂色」直接拉到 100%（视频 5:36 处）——放大看天空确实一点噪点都没有、非常纯净；但一缩小，一条一条的色彩带就全出来了（视频 5:50-5:58 处）。所以降噪只能对细节区域做，一定不要对纯色天空做：先复制一个图层再降噪，降噪完成后把天空部分抠出来填上黑色蒙板，让降噪只作用于地面（视频 6:01-6:29 处）。","xe":"The third red line is the most counterintuitive: noise reduction. If the photo contains a flat sky, denoising can backfire. In the example, the sky is clearly noisy at 100% zoom, so the Details → Noise Reduction slider in the Camera Raw filter gets dragged straight to 100% (at 5:36 in the video) — zoomed in, the sky is spotless; zoom out, and rows of color bands appear (at 5:50-5:58 in the video). Denoise detail areas only, never flat skies: duplicate the layer first, denoise it, then mask the sky out with black so the denoise only touches the ground (at 6:01-6:29 in the video)."},{"t":"img","f":"v06","w":852,"h":480},{"t":"img","f":"v07","w":852,"h":480},{"t":"p","x":"第四条红线是动感模糊。正常水面本来有很多细碎的细节和噪点，它们恰好把色彩断层掩盖住了；一旦施加动感模糊，水面被抹成一块纯色渐变区，断层立刻原形毕露（视频 6:41-7:02 处）。这种断层没法靠常规手段挽回，只能用后面说的加噪点方法来掩盖。","xe":"The fourth red line is motion blur. A normal water surface is full of fine texture and noise that conveniently mask any banding; once motion blur smooths the water into a pure gradient area, the bands stand exposed (at 6:41-7:02 in the video). This kind of banding cannot be fixed by conventional means — only the add-noise technique covered later can hide it."},{"t":"img","f":"v08","w":852,"h":480},{"t":"h","x":"03 两种原理性解法：色深与仿色","xe":"03 Two Fundamental Fixes: Bit Depth and Dithering"},{"t":"p","x":"消除色彩断层，原理上只有两条路。第一条是增加色彩深度：反复强调过，编辑时一定要用 16 位色深——它足够安全；至于 32 位，很多 PS 滤镜和操作并不支持，反而不实用（视频 7:11-7:33 处）。","xe":"Fundamentally there are only two ways to eliminate banding. The first is to increase the color depth: as repeated throughout the video, always edit at 16-bit — it is the safe sweet spot; go to 32-bit and many Photoshop filters and operations stop working, so it is impractical anyway (at 7:11-7:33 in the video)."},{"t":"img","f":"v09","w":852,"h":480},{"t":"p","x":"第二条是仿色（Dithering）。上面 7:39 处的 PPT 解释了它的原理：左边的大卫像其实只有黑白两种颜色，但靠着黑白点的疏密排列，乍一看居然有了灰色；同理，一个只有四种灰色的色带，如果中间加入抖动的杂点，看起来就变成了柔和的过渡——颜色没有变多，是「噪点」骗过了眼睛（视频 7:36-8:35 处）。PS 里拉渐变时勾上「仿色」选项，就能自动应用这套算法，避免渐变本身产生断层（视频 8:43-9:01 处）。","xe":"The second is dithering. The slide at 7:39 explains the principle: the statue of David on the left contains only two colors, black and white, yet the varying density of dots fakes convincing grays. Likewise, a banded gradient of just four grays turns into what looks like a smooth transition once dithered noise dots are interspersed — no new colors were added; the noise simply fools the eye (at 7:36-8:35 in the video). In Photoshop, checking the \"Dither\" box while dragging a gradient applies this algorithm automatically and keeps the gradient itself band-free (at 8:43-9:01 in the video)."},{"t":"img","f":"v10","w":852,"h":480},{"t":"h","x":"04 加噪点实操：50%灰叠加图层","xe":"04 Hands-On: the 50% Gray Overlay Noise Layer"},{"t":"p","x":"如果照片里已经产生了断层——比如为了雾化效果对水面做了动感模糊——唯一的解决方法就是加噪点，用噪点模拟仿色的效果，部分掩盖断层（视频 9:15-9:25 处）。做法：新建一个图层，执行「编辑 → 填充」，填充 50% 灰色，再把混合模式改成叠加——50% 灰在叠加模式下不可见，只有黑白杂点会显示出来（视频 9:28-9:46 处）。","xe":"If banding already exists — say you applied motion blur to the water for a misty look — the only fix is to add noise, letting it emulate dithering and partially mask the bands (at 9:15-9:25 in the video). The recipe: create a new layer, run Edit → Fill with 50% gray, then set the blend mode to Overlay — 50% gray is invisible in Overlay mode, so only the black-and-white noise specks show (at 9:28-9:46 in the video)."},{"t":"img","f":"v11","w":852,"h":480},{"t":"p","x":"接着执行「滤镜 → 杂色 → 添加杂色」：分布选平均分布或高斯分布都可以，数量一般在 1%-5% 之间，关键是勾选「单色」，否则加进来的会是彩色噪点（视频 9:47-10:08 处，上面 9:55 截图即该对话框）。加完之后再给这个图层加一点模糊——高斯模糊半径 0.5 像素左右，把杂点稍稍揉柔和一点（视频 10:22-10:35 处）。","xe":"Next run Filter → Noise → Add Noise: Uniform or Gaussian distribution both work, Amount generally between 1% and 5%, and critically check \"Monochromatic\" — otherwise the added grain will be colored (at 9:47-10:08 in the video; the dialog is captured at 9:55 above). Finish by blurring the layer slightly — a Gaussian blur of about 0.5 pixels softens the specks (at 10:22-10:35 in the video)."},{"t":"img","f":"v12","w":852,"h":480},{"t":"p","x":"效果立竿见影：视频 10:44 处的前后对比里，之前断层很猛的水面和天空，加噪点之后明显干净了很多（上面两张截图分别是 10:48 的断层特写与 10:52 加噪后的效果）。最后用图层蒙板控制范围：只把断层特别明显的水面和天空过渡区域用白色蒙板刷出来，让加噪点操作不影响其他区域的画质（视频 10:53-11:18 处）。","xe":"The effect is immediate: in the before/after at 10:44 in the video, the water and sky that banded badly look far cleaner after the noise was added (the two screenshots above show the banded close-up at 10:48 and the result at 10:52). Finally, control the scope with a layer mask: paint white only over the water and sky-transition areas where banding is worst, so the noise layer never touches the rest of the image quality (at 10:53-11:18 in the video)."},{"t":"img","f":"v13","w":852,"h":480},{"t":"img","f":"v14","w":852,"h":480},{"t":"quote","x":"1. 色彩断层源于 8-bit 每通道 256 级的颜色上限，渐变天空、近似纯色天空和雾化水面是重灾区；2. 预防四条红线：16 位色深编辑、HSL 不拉大幅值（用径向滤镜或选区整体提饱和）、纯色天空不降噪（黑色蒙板隔离）、慎用动感模糊；3. 原理性解法只有两个：提高色彩深度，以及用仿色/噪点骗过眼睛；4. 已有断层时，新建 50% 灰叠加图层，添加 1%-5% 单色杂点再 0.5 像素高斯模糊，白色蒙板只刷断层区域。","xe":"1. Banding comes from the 8-bit limit of 256 levels per channel; gradient skies, near-flat skies, and misty water are the disaster zones. 2. Four prevention red lines: edit at 16-bit, avoid extreme HSL moves (use a radial filter or a selection to raise saturation overall), never denoise flat skies (isolate them with a black mask), and be careful with motion blur. 3. Only two fundamental cures exist: raise the color depth, or use dithering/noise to fool the eye. 4. For existing banding, add a 50% gray Overlay layer, apply 1%-5% monochromatic noise, soften with a 0.5-pixel Gaussian blur, and paint it in with a white mask only where banding shows."},{"t":"h","x":"PPT","xe":"PPT"},{"t":"img","f":"img-02","w":960,"h":600},{"t":"img","f":"img-03","w":960,"h":600},{"t":"img","f":"img-04","w":960,"h":600},{"t":"img","f":"img-05","w":960,"h":600},{"t":"img","f":"img-06","w":960,"h":600},{"t":"img","f":"img-07","w":960,"h":600},{"t":"img","f":"img-08","w":960,"h":600},{"t":"h","x":"欢迎关注@Thomas看看世界","xe":"Follow @Thomas Chu Photo,"},{"t":"h","x":"每周学会一个摄影技能","xe":"and learn one photography skill every week."}],"titleEn":"Strange Bands in Your Sky? Preventing and Fixing Color Banding in Post"}