{"slug":"acr-lens-correction","title":"不要让畸变毁了你的照片 - ACR/Lightroom基本校正","author":"Thomas看看世界","date":"2016-08-28","wechat":"https://mp.weixin.qq.com/s?__biz=MzI4NDA5MzE5NQ==&mid=2247484265&idx=1&sn=649de5d044b350f22b5f85190b521051&scene=21#wechat_redirect","blocks":[{"t":"p","x":"摄影中很容易犯的一个错误，就是过于关注照片的曝光和色彩，而忽视了畸变、色差、污点给照片带来的巨大破坏。","b":false,"xe":"A common mistake in photography is focusing too much on exposure and color while overlooking the huge damage that distortion, aberration and spots do to a photo."},{"t":"p","x":"在ACR/Lightroom中后期处理的第一步，其实就是镜头校正，水平和透视校正，以及污点去除，纠正前期拍摄带来的问题。托马斯今天就会分享一下，如何在ACR或者Lightroom中进行这些基本校正。","b":false,"xe":"In ACR/Lightroom, the first step of post-processing is actually lens corrections, level & perspective corrections, and spot removal — fixing problems from the capture stage. Today Thomas shares how to perform these basic corrections in ACR or Lightroom."},{"t":"p","x":"知识点：桶形畸变、枕形畸变、透视畸变、晕影、色差、污点","b":false,"xe":"Topics: barrel distortion, pincushion distortion, perspective distortion, vignetting, chromatic aberration, spots"},{"t":"p","x":"阅读本文需要约11分钟","b":false,"xe":"Reading time: about 11 minutes"},{"t":"img","f":"img-02","w":900,"h":649},{"t":"p","x":"下面这张照片是一张典型的未校正照片。初一看我们会觉得色彩，以及长曝光带来的游船痕迹，都是很不错的。但照片总是有点不对劲的地方。","b":false,"xe":"The photo below is a typical uncorrected photo. At first glance the colors and the long-exposure boat trails look nice. But something about the photo feels off."},{"t":"p","x":"城市里的高楼大厦，在我们脑海中都是笔直、坚固的形象。但照片中的建筑群却因为透视畸变而东倒西歪，仿佛随时要向两边塌下去一样，给观者很不好的感觉。","b":false,"xe":"In our minds, city high-rises are straight and solid. Yet the buildings in this photo lean every which way due to perspective distortion, as if about to collapse sideways — an unpleasant feeling for viewers."},{"t":"img","f":"img-03","w":640,"h":427},{"t":"p","x":"上面这张照片的失误之处，就在于忽略了后期中重要的“基本校正”这一步。我们知道摄影分为前期拍摄和后期处理。在拍摄的时候，因为器材和拍摄环境的原因，我们的照片中会出现镜头畸变、晕影、色差、透视畸变、污点等等各种各样的前期问题。","b":false,"xe":"The flaw of the photo above is ignoring the important 'basic correction' step in post. Photography divides into capture and post-processing. During capture, equipment and environment introduce lens distortion, vignetting, chromatic aberration, perspective distortion, spots and other problems."},{"t":"p","x":"而后期处理的第一步，就是要进行“基本校正”，修复前期拍摄中的问题。决不能忽视这些问题，让他们在进一步的处理中不断放大，最终破坏我们的成片效果。","b":false,"xe":"The first step of post is 'basic correction' — fixing capture-stage problems. Never ignore them and let them amplify through further processing, ultimately ruining the final image."},{"t":"img","f":"img-04","w":640,"h":427},{"t":"h","x":"1","xe":"1"},{"t":"h","x":"镜头校正","xe":"Lens corrections"},{"t":"p","x":"当我们在ACR/Lightroom中打开一张图片，第一步最好不要直接就开始处理曝光和色彩。","b":false,"xe":"When opening an image in ACR/Lightroom, it's best not to start directly with exposure and color."},{"t":"img","f":"img-05","w":640,"h":373},{"t":"p","x":"而是应该打开面板列表中的第六个面板“镜头校正”，修复镜头带来的畸变、晕影和色差。","b":false,"xe":"Instead, open the sixth panel — 'Lens Corrections' — and fix the distortion, vignetting and chromatic aberration introduced by the lens."},{"t":"img","f":"img-06","w":640,"h":381},{"t":"p","x":"首先需要修复的是镜头带来的畸变。","b":false,"xe":"First to fix is lens distortion."},{"t":"p","x":"我们知道镜头内部是由一系列凸透镜和凹透镜组成的。这样不可避免的就带来了枕形和桶形这两种形状的畸变。","b":false,"xe":"A lens is made of a series of convex and concave elements, which inevitably produce pincushion and barrel distortion."},{"t":"p","x":"枕形畸变一般出现在长焦镜头中，物体本来的直线会向中间收缩，如同枕头一般。桶形畸变一般发生在广角端，画面边缘的直线向外膨胀，形成桶状。","b":false,"xe":"Pincushion distortion usually appears in telephoto lenses: straight lines contract toward the center, like a pillow. Barrel distortion usually occurs at wide angles: straight lines at the frame edges bulge outward, forming a barrel shape."},{"t":"img","f":"img-07","w":640,"h":325},{"t":"p","x":"仔细看这张广角拍摄的教堂内部，红圈圈出来的窗户和墙壁上，原本应该是笔直的线条，都不同程度的向外弯曲。这就是桶形畸变的表现。","b":false,"xe":"Look closely at this wide-angle church interior: the windows and walls circled in red, which should be perfectly straight lines, all bend outward to varying degrees. That's barrel distortion."},{"t":"img","f":"img-08","w":640,"h":425},{"t":"p","x":"除了畸变外，“晕影”也是镜头内部复杂结构所带来的。晕影又称为“暗角”，顾名思义就是照片周围会比中心暗一些。在大光圈的情况下，这种晕影尤其明显。（下图是35mm 1.8镜头，在不同光圈F值下的晕影表现）。有的时候晕影会给照片带来不错的画面效果，但更多时候我们还是需要矫正它。","b":false,"xe":"Besides distortion, 'vignetting' also comes from the lens's complex structure. Vignetting, also called 'dark corners', means the photo's edges are darker than the center. It's especially obvious at wide apertures. (Below: a 35mm f/1.8 lens's vignetting at various f-stops.) Sometimes vignetting adds a nice effect, but more often we need to correct it."},{"t":"img","f":"img-09","w":600,"h":400},{"t":"p","x":"矫正镜头畸变和晕影很简单，在镜头矫正-配置文件面板中，勾选“启用配置文件校正”即可。勾选之后，立马旁边窗户边缘变直了，同时四角也变亮了一些。","b":false,"xe":"Correcting lens distortion and vignetting is simple: in the Lens Corrections - Profile panel, tick 'Enable Profile Corrections'. Immediately the window edges straighten and the corners brighten."},{"t":"img","f":"img-10","w":640,"h":337},{"t":"p","x":"勾选“启用配置文件校正”之后，下面的镜头配置文件和校正量区域也被激活了。","b":false,"xe":"After ticking 'Enable Profile Corrections', the Lens Profile and Amount areas below activate."},{"t":"p","x":"镜头配置文件会自动探测照片的EXIF，识别出所用的镜头和相机，从而匹配相应的预设文件。当然我们也可以手动改变成其他的配置文件。","b":false,"xe":"The lens profile automatically reads the photo's EXIF, identifies the lens and camera, and matches the corresponding preset. Of course we can also manually switch to another profile."},{"t":"p","x":"校正量则显示了现在扭曲度和晕影的校正量，默认情况下是100%。如果我觉得原来桶形畸变的效果挺好的，那我可以把扭曲度滑块左移，降低扭曲度的校正量。","b":false,"xe":"The Amount section shows the current correction levels for distortion and vignetting — 100% by default. If I like the original barrel distortion, I can move the Distortion slider left to reduce the correction."},{"t":"img","f":"img-11","w":640,"h":361},{"t":"p","x":"如果我觉得畸变校正的还不够，我还可以提高扭曲度的校正量。可以看到本图扭曲度校正量提高到200%后，照片边缘从桶形畸变变成了枕形畸变，过犹不及。","b":false,"xe":"If I feel the distortion correction isn't enough, I can increase it. Below, with Distortion at 200%, the frame edges go from barrel to pincushion distortion — too much of a good thing."},{"t":"p","x":"同理的，我们也可以移动晕影滑块，来控制晕影的校正程度。","b":false,"xe":"Similarly, we can move the Vignetting slider to control the vignette correction."},{"t":"img","f":"img-12","w":640,"h":339},{"t":"p","x":"除了畸变和晕影，镜头常常还会出现色差。色差表现为照片中高光与暗部交界处，呈现出带有绿色或者紫色的边缘。比如放大教堂图片的窗户部分，可以看到亮光与玻璃框交界的地方，出现了绿色和紫色的边缘，这些就是色差。","b":false,"xe":"Besides distortion and vignetting, lenses often show chromatic aberration: green or purple fringes where highlights meet dark areas. Zooming into the church window, you can see green and purple fringes where bright light meets the frame — that's chromatic aberration."},{"t":"img","f":"img-13","w":640,"h":437},{"t":"p","x":"消除色差也非常的简单，在“启用配置文件校正”的上面，还有一个“删除色差”的选项。勾选“删除色差”，Adobe Camera Raw软件就会自动检测照片中的明暗交界处，删除掉绿色和紫色的色边。","b":false,"xe":"Removing chromatic aberration is also very simple: above 'Enable Profile Corrections' there's a 'Remove Chromatic Aberration' option. Tick it and Adobe Camera Raw automatically detects light-dark boundaries and removes the green and purple fringes."},{"t":"img","f":"img-14","w":640,"h":356},{"t":"p","x":"只要勾选了镜头校正-配置文件面板里的这两个选项，99.99%的镜头畸变、晕影和色差问题都可以完全解决掉，不需要再做任何其他工作。极少数不能解决的情况，还有镜头校正-手动面板，可以手动调整照片的扭曲度、去色差程度和晕影程度。","b":false,"xe":"With these two options in the Lens Corrections - Profile panel ticked, 99.99% of lens distortion, vignetting and chromatic aberration problems are completely solved — no other work needed. For the rare unsolved cases, there's the Lens Corrections - Manual panel for manual adjustment of distortion, defringe and vignetting."},{"t":"img","f":"img-15","w":440,"h":640},{"t":"p","x":"以上就是镜头校正的部分，只要轻松的勾选上“镜头校正-配置文件”面板中的两个选项，桶形畸变、枕形畸变、晕影、色差就统统一扫而光啦。","b":false,"xe":"That's the lens correction part — just tick the two options in the 'Lens Corrections - Profile' panel, and barrel/pincushion distortion, vignetting and chromatic aberration are all swept away."},{"t":"h","x":"2","xe":"2"},{"t":"h","x":"水平和透视校正","xe":"Level and perspective correction"},{"t":"p","x":"我们知道物体看起来都是近大远小的。我们有时为了拍到建筑的全貌，镜头不得不向上仰，这样就会出现下大上小的情况，原本平行的线条变成了汇聚的斜线。这种畸变我们成为透视畸变。","b":false,"xe":"We know objects appear near-big and far-small. Sometimes, to capture a whole building, we have to tilt the camera up — creating a big-bottom-small-top effect where parallel lines become converging diagonals. This distortion is called perspective distortion."},{"t":"img","f":"img-16","w":640,"h":472},{"t":"p","x":"有的时候我们相机拿的不平，照片中应该水平的线条如海平面等并不水平，这种问题我们称为水平线问题。水平线和透视畸变也是可以在ACR中轻松校正的。","b":false,"xe":"Sometimes we hold the camera unlevel, so lines that should be horizontal — like the sea horizon — aren't. We call this the horizon problem. Both horizon and perspective issues are easily corrected in ACR."},{"t":"p","x":"水平和透视校正工具，在早期的ACR版本中也是在镜头校正面板下的。但在最新的ACR软件中，你会看到这句提示“Upright已移动至Transform工具”，也就是说这些工具被移动到了箭头所指的Transform工具面板中（图标为一个梯形网格）。（Adobe的这个移动是有道理的，因为水平线和透视问题并不是镜头本身带来的，而是拍摄角度所致。）","b":false,"xe":"In early ACR versions, the level and perspective tools lived under Lens Corrections. In the latest ACR you'll see the note 'Upright has moved to the Transform tool' — these tools moved to the Transform panel (icon: a trapezoid grid). (Adobe's move makes sense: horizon and perspective problems come not from the lens itself but from shooting angle.)"},{"t":"img","f":"img-17","w":640,"h":375},{"t":"p","x":"点击“Transform变换”图标，ACR右侧就出现了变换面板。上面1、2、3、4、5、6所标的是我们最常用的6个按钮。下面还有7个手动滑块，99.999%的情况都不会用到。","b":false,"xe":"Click the 'Transform' icon and the Transform panel appears on ACR's right. Marks 1-6 are the 6 buttons we use most; the 7 manual sliders below are needed in 0.001% of cases."},{"t":"img","f":"img-18","w":640,"h":449},{"t":"p","x":"进入变换面板，默认选择的就是这个“圆中间一根斜线”的图标，表示没有进行任何水平和透视校正。","b":false,"xe":"Entering the Transform panel, the default selection is the 'circle with a diagonal line' icon — no level or perspective correction applied."},{"t":"img","f":"img-19","w":640,"h":345},{"t":"p","x":"后面的那个A图标，代表了Auto（自动）校正，点击之后ACR软件会自动分析图片，应用相应的水平和透视校正。这是非常智能的一个按钮，60%的情况下都可以准确的做出校正。","b":false,"xe":"The next icon, 'A', is Auto correction: click it and ACR automatically analyzes the image and applies level and perspective correction. A very smart button — accurate about 60% of the time."},{"t":"img","f":"img-20","w":640,"h":355},{"t":"p","x":"3号按钮（图标是正方形中间一根横线），表示只进行水平校正，也就是调整水平线。比如下面这张图，没有透视问题，只是海平面歪了。","b":false,"xe":"Button 3 (icon: a square with a horizontal line) applies level correction only — adjusting the horizon. Take the image below: no perspective problem, just a tilted sea level."},{"t":"img","f":"img-21","w":640,"h":435},{"t":"p","x":"点击3号“水平”按钮，瞬间ACR软件已经把海平面变平了。“水平”按钮其实就是ACR会自动检测出照片中的水平线，然后旋转照片把图像恢复成水平。","b":false,"xe":"Click button 3 'Level' and ACR instantly flattens the horizon. The 'Level' button makes ACR auto-detect horizontal lines in the photo and rotate the image back to level."},{"t":"img","f":"img-22","w":640,"h":340},{"t":"p","x":"下面这张照片，除了水平线问题外，还有纵向透视的问题。箭头所标的3条建筑上的直线，本来应该都是垂直于地面，互相平行的。但是现在这3条线却呈现出发散状。","b":false,"xe":"The photo below has vertical perspective problems on top of the horizon issue. The 3 straight building lines marked by arrows should be vertical to the ground and parallel to each other, but now they diverge."},{"t":"img","f":"img-23","w":640,"h":427},{"t":"p","x":"点击变换面板中的4号按钮（图标为正方形中3条竖线），就可以应用“水平和纵向透视校正”，也就是先纠正水平线，然后纠正纵向的透视问题。","b":false,"xe":"Click button 4 in the Transform panel (icon: a square with 3 vertical lines) to apply 'level + vertical perspective correction' — first fix the horizon, then the vertical perspective."},{"t":"img","f":"img-24","w":640,"h":351},{"t":"p","x":"5号按钮叫“水平、横向和纵向透视校正”（图标为正方形中既有横线又有竖线），也就是除了4号按钮校正的水平线和纵向透视外，还会尝试纠正横向的透视（也就是想把横向的物体都拉回一个平面）。这个按钮很少应用，一般反而会让照片产生如图所示的不良效果。。。","b":false,"xe":"Button 5 is 'level, horizontal and vertical perspective correction' (icon: a square with both horizontal and vertical lines) — beyond button 4's corrections, it also tries to fix horizontal perspective (pulling horizontal elements onto one plane). This button is rarely used and often produces the bad effect shown..."},{"t":"img","f":"img-25","w":640,"h":332},{"t":"p","x":"对于大部分照片，我们只需要挨个试下2-5这4个按钮，看看ACR自动处理的效果就行了。但是有时软件并不能很好的分析出照片中的透视情况，比如这张教堂的图片，在我选了2号按钮（A自动校正）的情况下，窗户还是斜的，桌子也是歪的。","b":false,"xe":"For most photos, we only need to try buttons 2-5 one by one and see ACR's automatic results. But sometimes the software can't analyze the perspective well — for this church image, with button 2 (Auto) applied, the windows are still tilted and the table is crooked."},{"t":"img","f":"img-26","w":640,"h":333},{"t":"p","x":"这个时候就需要用到终极武器 - 指导线校正了（6号按钮，图标为交叉的2条水平线和2条垂直线）。（老版的ACR软件中没有这个终极武器，赶快更新吧）","b":false,"xe":"That's when we need the ultimate weapon — Guided correction (button 6, icon: 2 crossed horizontal and 2 vertical lines). (Older ACR versions lack this weapon — update now!)"},{"t":"img","f":"img-27","w":640,"h":354},{"t":"p","x":"选了这个按钮后，我们可以拖动鼠标在图像中画出2-4条指导线。指导线要画在照片里实际上应该水平或者竖直的地方。一般先画2条竖直方向的指导线，纠正透视畸变。","b":false,"xe":"With this button selected, we drag the mouse to draw 2-4 guide lines in the image. Guide lines should be drawn along features that should actually be horizontal or vertical. Usually draw 2 vertical guides first to fix perspective distortion."},{"t":"p","x":"比如左边的窗户边缘，本来应该是竖直的，我就沿着窗户边缘拖动鼠标，画出第一条指导线。（这个时候画面没有变化，因为ACR需要至少2条指导线才能分析图片。）","b":false,"xe":"For example, the left window edge should be vertical, so I drag along it to draw the first guide line. (Nothing changes yet — ACR needs at least 2 guides to analyze.)"},{"t":"img","f":"img-28","w":640,"h":432},{"t":"p","x":"右边的墙壁上，也有本来应该垂直的线条，在这也拉一根指导线。（备注：在透视校正前一定要先进行镜头校正，不然这儿的墙壁线条还是桶形畸变弯曲的。。。）","b":false,"xe":"On the right wall there's another line that should be vertical — draw a guide there too. (Note: always do lens correction before perspective correction, or the wall lines here are still bent by barrel distortion...)"},{"t":"img","f":"img-29","w":640,"h":428},{"t":"p","x":"画出第二条线后松开鼠标，奇迹出现，两条指导线所在的线条都变得垂直于地面。不过这个时候桌子还是歪的。","b":false,"xe":"Release the mouse after the second line — a miracle: both guided lines become perpendicular to the ground. But the table is still crooked."},{"t":"img","f":"img-30","w":640,"h":349},{"t":"p","x":"所以再水平画一条指导线，标出水品面，这里我沿着桌子上缘画了一条。","b":false,"xe":"So draw one more horizontal guide to mark the level plane — here along the table's top edge."},{"t":"img","f":"img-31","w":640,"h":432},{"t":"p","x":"松开鼠标，桌子变成了水平，同时窗户和墙壁也继续保持垂直状态。","b":false,"xe":"Release the mouse — the table becomes level while the windows and walls stay vertical."},{"t":"img","f":"img-32","w":640,"h":343},{"t":"p","x":"当当当，看一下前后对比图吧，下面横平竖直的教堂是不是更加庄严肃穆了呢？","b":false,"xe":"Ta-da — check the before/after: doesn't the perfectly squared church below look more solemn and majestic?"},{"t":"img","f":"img-33","w":482,"h":640},{"t":"p","x":"下面这张树木的照片也是几个自动按钮无法校正的，树木像要往中间倒了一般。只能运用“指导线”神器。","b":false,"xe":"This photo of trees below also defeats the auto buttons — the trees seem to fall toward the center. Only the 'Guided' tool can save it."},{"t":"img","f":"img-34","w":640,"h":335},{"t":"p","x":"沿着2颗树画两条竖直方向指导线，沿着建筑水平面画一条横向指导线，横平竖直的画面就回来了。","b":false,"xe":"Draw two vertical guides along the two trees and one horizontal guide along the building's level plane — the squared-up frame returns."},{"t":"img","f":"img-35","w":640,"h":343},{"t":"p","x":"裁剪后比较一下前后效果，校正的威力不言而喻。","b":false,"xe":"Compare before and after cropping — the power of correction speaks for itself."},{"t":"img","f":"img-36","w":546,"h":640},{"t":"p","x":"竖直方向的指导线一般选在画面边缘的位置比较好，因为画面边缘比中心的畸变更加明显。","b":false,"xe":"Vertical guide lines are best placed near the frame edges, where distortion is more pronounced than at the center."},{"t":"img","f":"img-37","w":640,"h":429},{"t":"p","x":"一般来说一条水平指导线就够了，可以让画面恢复水平。如果画面有横向透视畸变的话，我们还可以画第二条水平指导线，纠正横向畸变。","b":false,"xe":"Generally one horizontal guide is enough to restore level. If the frame has horizontal perspective distortion, draw a second horizontal guide to correct it."},{"t":"p","x":"比如这张勃兰登堡门的照片，左右两边的建筑应该是一样大的，但是由于水平透视的关系，右边的建筑比左边还大。","b":false,"xe":"In this Brandenburg Gate photo, the buildings on the left and right should be the same size, but due to horizontal perspective, the right one is larger than the left."},{"t":"img","f":"img-38","w":640,"h":345},{"t":"p","x":"所以这张照片我画了4条指导线，2条横向2条纵向，在解决水平线和纵向透视畸变的同时，还解决了横向的透视畸变。","b":false,"xe":"So for this photo I drew 4 guides — 2 horizontal and 2 vertical — fixing horizon and vertical perspective plus the horizontal perspective distortion."},{"t":"img","f":"img-39","w":640,"h":369},{"t":"h","x":"3","xe":"3"},{"t":"h","x":"污点去除","xe":"Spot removal"},{"t":"p","x":"消除了镜头带来的畸变和色差，解决了拍摄方向带来的透视问题，前期还有一个薄弱环节就是相机感光芯片上的脏点问题了。在换镜头的时候有时会有灰尘进入相机，在照片上留下一些脏点污点。","b":false,"xe":"With lens distortion and aberration eliminated and perspective fixed, one remaining capture-stage weakness is dust on the camera sensor. Dust can enter when changing lenses, leaving dirty spots on photos."},{"t":"p","x":"擦除污点很简单，选择ACR上方的“污点去除”工具（笔刷加十字星的图标），鼠标再移动到画面里的时候就会变成画笔形状。改变画笔大小，涂抹在有污点的地方，ACR就会自动寻找相似纹理把这些污点区域覆盖起来啦。","b":false,"xe":"Removing spots is simple: select the 'Spot Removal' tool at the top of ACR (the brush-with-sparkle icon); the mouse becomes a brush in the image. Adjust the brush size and paint over spots — ACR automatically finds similar texture to cover them."},{"t":"img","f":"img-40","w":640,"h":375},{"t":"h","x":"本周总结","xe":"Weekly summary"},{"t":"quote","x":"1. 后期处理的第一步就是基本校正，分为镜头校正，水平和透视校正，以及污点去除三步。 2. 勾选镜头校正-配置文件面板中的2个选项，就可以轻松解决镜头带来的桶形/枕形畸变、晕影和色差了 。 3. 在Transform变换工具中，可以校正照片的水平线和透视畸变问题。一般情况应用第2-5个按钮，就可以让软件自动分析并修正问题。否则我们可以用第6个（指导线）按钮，通过在图像中画出竖直和水平的指导线来帮助软件进行校正。 4. 用污点清除工具的画笔，涂抹在照片污点处，就可以除去照片的污点 。","xe":"1. The first step of post is basic correction: lens corrections, level & perspective corrections, and spot removal. 2. Tick the 2 options in Lens Corrections - Profile to easily fix barrel/pincushion distortion, vignetting and chromatic aberration. 3. In the Transform tool you can correct horizon and perspective problems — usually buttons 2-5 let the software auto-analyze and fix; otherwise use button 6 (Guided) to draw vertical and horizontal guides. 4. Paint over spots with the Spot Removal brush to erase them."},{"t":"p","x":"我是@Thomas看看世界，每个周日晚上，分享一篇原创摄影干货。","b":false,"xe":"I'm @Thomas Chu Photo — every Sunday evening I share an original piece of photography know-how."},{"t":"img","f":"img-41","w":640,"h":313}],"titleEn":"Don't Let Distortion Ruin Your Photos: Basic Corrections in ACR/Lightroom"}