{"slug":"ps-curves-part1","title":"PS曲线(上) - 如何用它让照片影调焕然一新","author":"Thomas看看世界","date":"2016-06-05","wechat":"https://mp.weixin.qq.com/s?__biz=MzI4NDA5MzE5NQ==&mid=2247483949&idx=1&sn=fb598e236e375b23820de356092689c7&scene=21#wechat_redirect","blocks":[{"t":"p","x":"如果说前两周讲到的直方图是摄影师的“X光片”，那么曲线工具一定是摄影师的“手术刀”了。","b":false,"xe":"If the histogram from the last two weeks is the photographer's 'X-ray', then the Curves tool must be the photographer's 'scalpel'."},{"t":"p","x":"曲线作为重要的影调和色调调整工具，不仅存在于Photoshop中，在ACR，Lightroom甚至其他很多手机P图软件中都占据着显眼的位置。本篇文章，就将详细谈谈什么是RGB曲线，如何使用提亮压暗、黑白场、对比度，以及局部调整曲线等基本形态，调整一张照片的影调。","b":false,"xe":"As an essential tonal and color adjustment tool, Curves sits prominently not only in Photoshop but also in ACR, Lightroom and even many phone editing apps. This article explains in detail what the RGB curve is, and how to use basic shapes — brighten/darken, black-white point, contrast, and local curves — to adjust a photo's tonality."},{"t":"p","x":"下一周的PS曲线(下)，会继续讲解如何把各种基本曲线形态组合起来，达到胶片、漂白、日系等等更复杂的影调效果。","b":false,"xe":"Next week's PS Curves (Part 2) will continue with how to combine these basic shapes for more complex looks like film, bleach and Japanese styles."},{"t":"img","f":"img-02","w":640,"h":425},{"t":"h","x":"曲线工具在哪？","xe":"Where is the Curves tool?"},{"t":"p","x":"曲线面板在Lightroom和Adobe Camera Raw工具中，都是紧接着基本面板的第二个面板，足以感受到它的重要性。","b":false,"xe":"In both Lightroom and Adobe Camera Raw, the Tone Curve panel is the second panel right after Basic — a hint of its importance."},{"t":"img","f":"img-03","w":560,"h":457},{"t":"p","x":"在Photoshop中，我们一般会使用曲线调整图层来改变曲线。在PS中图层面板的右下角，第四个图标就是“新建调整图层”选项，点击后选择“曲线”，我们就可以新建一个“曲线调整图层”。","b":false,"xe":"In Photoshop we usually use a Curves adjustment layer. At the bottom right of PS's Layers panel, the fourth icon is 'New Adjustment Layer' — click it and choose 'Curves' to create one."},{"t":"img","f":"img-04","w":897,"h":481},{"t":"p","x":"新建调整图层，而不是在原图层上直接改变曲线。优点就是可以让我们方便的撤销/恢复所做的任意调整。","b":false,"xe":"Creating an adjustment layer instead of changing the curve directly on the original layer lets us conveniently undo/redo any adjustment."},{"t":"h","x":"曲线是什么？","xe":"What is a curve?"},{"t":"p","x":"本文将重点讲解RGB通道曲线，它是由红（R）绿（G）蓝（B）三个通道的曲线叠加而成的，可以“近似的”理解成图片的亮度曲线。","b":false,"xe":"This article focuses on the RGB channel curve, formed by overlaying the curves of the Red, Green and Blue channels — it can be 'approximately' understood as the image's brightness curve."},{"t":"h","x":"RGB曲线调整的核心其实就是对原图亮度的变换。","xe":"The core of RGB curve adjustment is transforming the original image's brightness."},{"t":"p","x":"曲线的横轴是原图的亮度分布，从左到右依次是0值纯黑，1-254的中间灰色值，以及最右边255的纯白最亮值。横轴上叠加着一个直方图，显示出原图各个亮度上，分别存在着多少像素。","b":false,"xe":"The curve's horizontal axis is the original image's brightness distribution: from left to right, 0 for pure black, 1-254 for mid-grays, and 255 for the brightest pure white. A histogram is overlaid on the axis, showing how many pixels exist at each brightness."},{"t":"p","x":"曲线的纵轴是目标图（调整后）的亮度，从下到上仍然是0-255的亮度值。","b":false,"xe":"The curve's vertical axis is the target (adjusted) brightness, again 0-255 from bottom to top."},{"t":"p","x":"当中的那根线就是我们的“曲线”。当我们在曲线上任意取一个点，它的“输入值”就是它横轴对应的值，即原图中的亮度，它的“输出值”就是它纵轴中的数值，也就是调整后它的亮度值。","b":false,"xe":"The line in the middle is our 'curve'. Pick any point on it: its 'input value' is its horizontal-axis value — the original brightness; its 'output value' is its vertical-axis value — the adjusted brightness."},{"t":"p","x":"未调整的情况下，图像的曲线会是一条对角线，也就是横轴（原图）和纵轴（目标图）的亮度值相等。比如我在曲线上取了一个点，它的输入和输出值都是193.","b":false,"xe":"Unadjusted, the curve is a diagonal — input (original) and output (target) brightness are equal. Here I picked a point whose input and output are both 193."},{"t":"img","f":"img-05","w":893,"h":506},{"t":"p","x":"如果我把这个点往上移动，可以看到这个点的输出值变成了232.这意味着原图直方图上那些193亮度的点，都被提亮到了更亮的232。","b":false,"xe":"If I move this point up, its output becomes 232 — meaning all pixels at brightness 193 in the original histogram are brightened to 232."},{"t":"p","x":"同时我们可以发现曲线的一个特点，当我们变动一个点的时候，旁边的点也会跟着一起变化，离调整点越远的点变化越小。这样使得曲线调整的图片，大多数情况都比较的平滑自然。","b":false,"xe":"Notice a key trait of curves: when we move one point, neighboring points move along — the further from the adjusted point, the smaller the change. This keeps curve-adjusted images smooth and natural in most cases."},{"t":"img","f":"img-06","w":886,"h":491},{"t":"p","x":"通过在曲线上添加控制点（锚点），我们就可以把曲线变成各种各样的形态，从而达到我们想要的影调效果。接下来我就会通过一些基本的曲线形态，来进一步的解释曲线。","b":false,"xe":"By adding control points (anchors) to the curve, we can bend it into all kinds of shapes to achieve the tonal effect we want. Next I'll explain curves through some basic shapes."},{"t":"img","f":"img-07","w":893,"h":501},{"t":"h","x":"提亮压暗曲线","xe":"Brighten and darken curves"},{"t":"p","x":"提亮和压暗一张图片，并不是我们想象中的对图片中所有点都加大减小同样的亮度值。比如下面这个曲线，就是把图像上所有的点亮度都提高了64。这样造成了2个不好的结果：","b":false,"xe":"Brightening or darkening an image is not adding or subtracting the same brightness value for every point, as you might imagine. The curve below, for instance, raises every pixel's brightness by 64, causing 2 bad results:"},{"t":"p","x":"（1）图片的高光区域直接过曝溢出了","b":false,"xe":"(1) The highlights blow out directly"},{"t":"p","x":"（2）图片的阴影和黑色区域亮度大大提高，使得图片黑场不足，严重发灰。","b":false,"xe":"(2) The shadows and blacks brighten drastically, starving the image of true black and making it seriously gray."},{"t":"img","f":"img-08","w":852,"h":496},{"t":"p","x":"所以我们一般提亮图片都是用如下的曲线，把锚点放在中间调附近往上提。这样照片主要是中间调的亮度大幅提高。高光区域亮度提高较少，防止了过曝。阴影黑色区域提升也不多，较好的维持了图像的对比反差程度。","b":false,"xe":"So we usually brighten with a curve like this: place the anchor near the midtones and lift. The photo's midtones brighten most; highlights rise less, preventing blowout; shadows and blacks rise only slightly, preserving contrast."},{"t":"img","f":"img-09","w":900,"h":496},{"t":"p","x":"同样的，我们要压暗一张图片，也是用锚点下拉图片的中间调。保护阴影区域不欠曝，让高光白色区域维持住对比度。","b":false,"xe":"Likewise, to darken an image we anchor the midtones and pull down — protecting shadows from underexposure and keeping contrast in highlights and whites."},{"t":"img","f":"img-10","w":879,"h":497},{"t":"h","x":"黑白场曲线","xe":"Black-point/white-point curves"},{"t":"p","x":"我们把照片上最暗的点叫做黑场，最亮的点叫做白场，黑白场的差值决定了一张照片的反差程度。","b":true,"xe":"We call the darkest point of a photo the black point and the brightest the white point; the difference between them determines the photo's contrast."},{"t":"h","x":"通过横移和竖移曲线的左右两端，就可以加大和减小照片的黑白场差值。","xe":"By shifting the curve's left and right endpoints horizontally or vertically, we widen or narrow that black-white difference."},{"t":"p","x":"比如下面这张图片就是一张灰蒙蒙的低反差图片，照片最暗的地方也只是亮度高达50多的深灰色，照片最亮的地方也只是200多的浅灰色。照片的黑色和白色区域完全没有像素。","b":false,"xe":"The image below is a grayish, low-contrast picture: its darkest area is only a dark gray above 50, its brightest a light gray just past 200. The black and white regions have no pixels at all."},{"t":"img","f":"img-11","w":881,"h":496},{"t":"p","x":"所以我把曲线最右侧横向左移，此时原来亮度值（输入值）219的像素，全部被提亮到了255（输出值）的纯白色。照片中终于有了亮白的部分。","b":false,"xe":"So I moved the curve's right end leftward horizontally — pixels originally at input 219 all brighten to output 255, pure white. The photo finally has bright white parts."},{"t":"img","f":"img-12","w":901,"h":512},{"t":"p","x":"同样我在曲线最左侧建立一个锚点，横向右拉，此时原来亮度值55的深灰色区域，就全部输出成了亮度为0的纯黑区域。照片中又有了深黑色。通过这两步，我们加大了照片黑白场的差距，照片的反差就大大提高了。","b":false,"xe":"Similarly, I created an anchor at the curve's left end and pulled it right horizontally — the original dark-gray area at 55 all outputs as pure black at 0. The photo regains deep blacks. These two steps widen the black-white gap, greatly increasing contrast."},{"t":"img","f":"img-13","w":906,"h":513},{"t":"p","x":"黑白场差值大的图片一般层次丰富，鲜艳锐利。但是照片的黑白场差值并不是越高越好。一个很大的误区就是照片的黑场一定要是0，白场必须为255。","b":false,"xe":"Images with a large black-white gap are generally rich, vivid and sharp. But bigger isn't always better. A common misconception is that the black point must be 0 and the white point 255."},{"t":"p","x":"实则不然，比如这张照片，照片的黑场是0，照片中有许多深黑区域，显得反差比较大，可能并不是我们想要的效果。","b":false,"xe":"Not really — take this photo: its black point is 0, and the many deep-black areas give strong contrast, which may not be the effect we want."},{"t":"img","f":"img-14","w":852,"h":487},{"t":"p","x":"我在曲线最左侧建立一个锚点，纵向上拉。这样输入值为0的纯黑部分，亮度被提高到了38。照片中不再有纯黑，最暗的部分（也就是黑场）也是亮度38的深灰色，这样的照片看起来更加的朦胧淡雅，符合我们想要的气氛。","b":false,"xe":"I created an anchor at the curve's left end and pulled it up vertically: input 0 (pure black) is lifted to brightness 38. The photo no longer has pure black — the darkest part (the black point) is a dark gray at 38. The photo looks softer and more ethereal, matching the mood we want."},{"t":"img","f":"img-15","w":875,"h":501},{"t":"h","x":"对比度曲线","xe":"Contrast curves"},{"t":"p","x":"对比度曲线，其实就是摄影里几乎人人皆知的S型曲线和反S型曲线了。","b":false,"xe":"Contrast curves are the nearly universal S-curve and inverse-S-curve of photography."},{"t":"img","f":"img-16","w":942,"h":571},{"t":"p","x":"增强对比度曲线（S型曲线），其实就是在高光处建立锚点并提高，在阴影处建立锚点并降低，拉出一个像英语字母S一样的曲线。","b":false,"xe":"The contrast-increasing curve (S-curve) is simply an anchor raised in the highlights and an anchor lowered in the shadows, forming a shape like the letter S."},{"t":"img","f":"img-17","w":915,"h":576},{"t":"p","x":"仔细观察S曲线，或许我们就能理解到其背后的原理。前面的教程我们提到过，一张照片按亮度从低到高分为黑色，阴影，中间调（曝光度），高光和白色5个部分。","b":false,"xe":"Look closely at the S-curve and we can understand the principle behind it. Earlier tutorials mentioned that a photo divides into 5 brightness parts: Blacks, Shadows, Midtones (Exposure), Highlights and Whites."},{"t":"p","x":"其中中间调区域的过渡与细节最为细腻。可以看到S型曲线中间部分，输入和输出值变化很小。所以S曲线在中间调区域的影响并不大，很好的保护了照片细节最丰富的部分。","b":false,"xe":"The midtone region has the finest transitions and detail. In the middle of the S-curve, input and output barely change — so the S-curve barely affects the midtones, protecting the photo's most detail-rich part."},{"t":"p","x":"白色和黑色区域在最两端，S型曲线对这些亮度区域的改变也不大，有效防止了过曝和欠曝溢出。","b":false,"xe":"Whites and Blacks sit at the extreme ends, where the S-curve also changes little — effectively preventing over- and under-exposure clipping."},{"t":"p","x":"S曲线主要是提高了原来照片中高光部分的亮度，降低了阴影部分的亮度，让照片的影调更加偏向硬调。因此S曲线在保护黑白色与中间调细节的前提下，有效的提高了照片的对比度，几乎成为了大部分照片必用的一步。","b":false,"xe":"The S-curve mainly raises the highlights' brightness and lowers the shadows', pushing the photo toward harder gradation. Protecting the black/white points and midtone detail while effectively raising contrast, the S-curve has become an almost mandatory step for most photos."},{"t":"img","f":"img-18","w":600,"h":521},{"t":"p","x":"类似的，如果我们降低高光锚点，提高阴影锚点，形成一个反S的形状。就是降低对比度曲线了。","b":false,"xe":"Similarly, lowering the highlight anchor and raising the shadow anchor forms an inverse-S — the contrast-reducing curve."},{"t":"h","x":"局部调整曲线","xe":"Local adjustment curves"},{"t":"p","x":"前面三个曲线形态都是作用在照片的全局。但数码后期的一个核心思路，就是局部调整照片不同的区域，让每个区域在展现出最好效果的同时不要影响到其他区域。","b":false,"xe":"The three shapes above act on the whole photo. But a core idea of digital post is adjusting different regions locally — letting each area look its best without affecting others."},{"t":"p","x":"比如这张图片，雪山和湖之间的草地一片漆黑，需要提亮。","b":false,"xe":"In this image, for example, the grass between the snow mountain and the lake is pitch black and needs brightening."},{"t":"img","f":"img-19","w":902,"h":506},{"t":"p","x":"如果我直接应用提亮曲线，草地倒是变亮了，但雪山（高光部分）和天空（中间调部分）一下子就过曝了。","b":false,"xe":"Applying a brighten curve directly brightens the grass — but the snow mountain (highlights) and sky (midtones) blow out instantly."},{"t":"img","f":"img-20","w":897,"h":513},{"t":"p","x":"所以我需要建立两个锚点，把提亮的高光和中间调部分重新拉回来。这样这条曲线就只提高了照片阴影部分的亮度。","b":false,"xe":"So I create two anchors to pull the highlight and midtone parts back down. Now the curve only raises the shadows' brightness."},{"t":"img","f":"img-21","w":889,"h":500},{"t":"p","x":"在局部调整曲线时，有一个非常有用的工具。就是圆圈中那个手一样的图标，点击它之后再把鼠标移动到图像里面，鼠标就会变成一个吸管，同时在右边曲线面板里，会实时显示吸管所在点对应在曲线里的位置。","b":false,"xe":"For local curve work there's a very useful tool: the hand-like icon in the circle. Click it, move the mouse into the image, and it becomes an eyedropper — while the curve panel on the right shows in real time where the eyedropper's point maps on the curve."},{"t":"p","x":"单击吸管，吸管所在的点，就会对应成一个锚点记录在直方图上，方便我们调整。","b":false,"xe":"Click with the eyedropper and that point is recorded as an anchor on the histogram for easy adjustment."},{"t":"p","x":"比如这张图，我想降低深色的山体的亮度，同时又保持住白色雾气的亮度。所以我选择“手”图标后，先在红圈1的山体处点一下，曲线中对应建立了1锚点。再在雾气的红圈2处点一下，曲线中就建立了对应的2锚点。","b":false,"xe":"In this image I want to darken the deep-colored mountain while keeping the white mist bright. After selecting the 'hand' icon, I click the mountain at red circle 1 — anchor 1 appears on the curve. Then I click the mist at red circle 2 — anchor 2 appears."},{"t":"img","f":"img-22","w":906,"h":503},{"t":"p","x":"这样我下压1锚点，同时保持住2锚点，就只降低了阴影的山体区域，而高光的雾气则没有被影响。","b":false,"xe":"Now I push anchor 1 down while holding anchor 2 — only the shadowed mountain region darkens; the highlight mist is unaffected."},{"t":"img","f":"img-23","w":855,"h":467},{"t":"h","x":"本周总结/下周预告","xe":"Weekly summary / next week preview"},{"t":"p","x":"本周主要讲了RGB曲线是什么。通过提亮压暗曲线，黑白场曲线，对比度曲线三种基本形态，以及对他们的局部应用，就可以快速的调整一张照片的影调了。","b":false,"xe":"This week covered what the RGB curve is. With three basic shapes — brighten/darken, black-white point, contrast — plus their local application, you can quickly adjust a photo's tonality."},{"t":"p","x":"下个周日的《PS曲线（下）》，将会进一步谈谈如何把这几种基本曲线组合起来，调出复杂的胶片，漂白，日系等等效果。","b":false,"xe":"Next Sunday's 'PS Curves (Part 2)' will further discuss combining these basic curves for complex film, bleach and Japanese-style effects."},{"t":"img","f":"img-24","w":1000,"h":726},{"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-25","w":360,"h":600}],"titleEn":"PS Curves (Part 1): Refresh Your Photo's Tonality with Curves"}