{"slug":"protect-image-quality","title":"如何在后期时最大限度的保护画质？","author":"Thomas看看世界","date":"2017-01-02","wechat":"https://mp.weixin.qq.com/s?__biz=MzI4NDA5MzE5NQ==&mid=2247484810&idx=1&sn=ea56ea9ddffed57c441e491020da9ce1&chksm=eb81fbeedcf672f86dd7fb96712bef1216469558b83709689e558f217c3998624067476423ad&scene=21#wechat_redirect","blocks":[{"t":"p","x":"如何在后期时最大限度的减少噪点，提升细节，增强色彩？","b":false,"xe":"How can we minimize noise, maximize detail, and strengthen color in post-processing?"},{"t":"p","x":"本文会分享托马斯在风光后期实践中注意到的，对画质影响较多的6大板块：","b":false,"xe":"This article shares the six areas Thomas has found to matter most for image quality in his landscape post-processing practice:"},{"t":"p","x":"1. 增加前期记录的信息","b":false,"xe":"1. Capture more information in the field"},{"t":"p","x":"2. 锐化和降噪的顺序","b":false,"xe":"2. The order of sharpening and noise reduction"},{"t":"p","x":"3. 多步少量原则","b":false,"xe":"3. The \"many small steps\" principle"},{"t":"p","x":"4. 非破坏性调整","b":false,"xe":"4. Non-destructive adjustments"},{"t":"p","x":"5. 局部应用调整","b":false,"xe":"5. Apply adjustments locally"},{"t":"p","x":"6. 使用最新技术以及专业插件","b":false,"xe":"6. Use the latest technology and professional plugins"},{"t":"h","x":"1","xe":"1"},{"t":"h","x":"增加前期记录的信息","xe":"Capture More Information in the Field"},{"t":"p","x":"虽然本文标题是后期，但是后期指导前期，后期依赖前期。","b":false,"xe":"Although this article is about post-processing, post guides the capture — and depends on it."},{"t":"h","x":"后期中对画质改观最强大的一些武器，都需要前期拍摄时的支持。","xe":"The most powerful weapons for transforming image quality in post all rely on support from the field."},{"t":"p","x":"比如大家经常听说的使用raw格式拍摄，相机设置AdobeRGB色彩空间，和使用14bit色彩深度记录等等，本质上就是增加前期纪录信息的质量和数量。","b":true,"xe":"For example, the often-heard advice — shoot raw, set the camera to the Adobe RGB color space, record in 14-bit depth — is essentially about increasing the quality and quantity of information captured in the field."},{"t":"p","x":"又比如现代风光摄影中，","b":false,"xe":"Or consider modern landscape photography:"},{"t":"p","x":"让画面噪点最少的方式，是堆栈降噪，以及适当向右曝光再拉回，都依赖前期的拍摄。","b":false,"xe":"the way to minimize noise is stacking for noise reduction, plus exposing to the right and pulling back — both depend on how you shoot."},{"t":"p","x":"让暗部亮部细节最自然的办法，是曝光合成，需要前期的包围曝光拍摄。","b":false,"xe":"The most natural way to hold highlight and shadow detail is exposure blending, which requires bracketed shooting in the field."},{"t":"p","x":"让画面从前景一直锐到背景的武器，是景深合成，更离不开前期了。","b":false,"xe":"And the weapon that keeps a scene sharp from foreground to background — focus stacking — is even more dependent on field technique."},{"t":"p","x":"现代摄影，不再局限于单张照片有限的信息，而是基于几张十几张 raw格式文件的海量优质原始数据，各种后期武器的精度都是指数级的提高！","b":true,"xe":"Modern photography is no longer limited to the finite information of a single frame; it's built on massive, high-quality raw data from several or a dozen-plus frames, and the precision of every post-processing weapon improves exponentially!"},{"t":"p","x":"以星空摄影为例，如果你单张ISO3200，拍出来地面和星空的噪点肯定很多。基于单张照片有限的信息，各种降噪算法在细节和噪点中间也总是难以完美平衡，一旦强拉暗部，噪点更是非常恐怖！","b":false,"xe":"Take astrophotography: a single frame at ISO 3200 will be full of noise in both the ground and the sky. With the limited information of one frame, noise-reduction algorithms always struggle to balance detail against noise — lift the shadows hard, and the noise is horrific!"},{"t":"img","f":"img-02","w":1000,"h":661},{"t":"p","x":"但如果前期连续拍摄5张照片，后期用平均值或者中间值堆栈降噪方式的话，噪点就可以被大幅度的减少，而且细节同时没有被损失。","b":false,"xe":"But shoot five consecutive frames in the field and stack them in post with mean or median noise reduction, and noise drops dramatically — with no loss of detail."},{"t":"p","x":"下面的上图是单张效果，下图是5张中间值堆栈后：","b":false,"xe":"Below: the top image is a single frame; the bottom is the median stack of five frames."},{"t":"img","f":"img-03","w":549,"h":800},{"t":"p","x":"关于如何对星空和地面分开堆栈降噪，具体步骤我已经写在教程《如何用普通单反拍出低噪点的银河星空》之中了。","b":false,"xe":"I've written the exact steps for stacking the sky and ground separately in the tutorial \"How to Shoot Low-Noise Milky Way Photos with an Ordinary DSLR.\""},{"t":"p","x":"当然，上面是5张降噪，如果你时间充裕、电脑给力的话，基于更多原片进行堆栈肯定降噪更强力（当然提升效应会不断减弱）。","b":false,"xe":"That's five frames for noise reduction; with ample time and a capable computer, stacking even more source frames is stronger still (with diminishing returns, of course)."},{"t":"img","f":"img-04","w":1000,"h":607},{"t":"p","x":"多张拍摄，是一种增加原始数据的办法。但是还有其他的前期方法。","b":false,"xe":"Multi-frame shooting is one way to increase your raw data — but there are other field methods."},{"t":"p","x":"比如星空，使用便携赤道仪抵消地球自转的话，可以长曝光10分钟，ISO降低到800一下，这个画质提升就更大了。","b":false,"xe":"For the starry sky, a portable star tracker counteracts Earth's rotation, allowing 10-minute exposures at ISO 800 or below — an even bigger jump in quality."},{"t":"img","f":"img-05","w":1000,"h":574},{"t":"p","x":"再说星空照片的地景，晚上黑不溜秋的，就算拍100张收集到的光线信息也比较有限。不如直接使用人工补光，光线质量指数级飞跃。","b":false,"xe":"Then there's the foreground of a night shot: pitch black at night, so even 100 frames gather limited light information. Better to add artificial lighting for an exponential leap in light quality."},{"t":"img","f":"img-06","w":1000,"h":668},{"t":"p","x":"当然还有一种很流行的强力办法，就是天还没黑时拍摄地景，保持机位不动晚上再拍摄星空进行叠加，地景参数ISO 200。。。画质就跟白天一模一样了。。。","b":false,"xe":"Another popular power move: shoot the foreground before dark, keep the camera position fixed, and shoot the sky later that night, blending the two. Foreground at ISO 200... the quality matches daylight exactly..."},{"t":"img","f":"img-07","w":1000,"h":668},{"t":"p","x":"所以说前期拍摄出高质量的原片，收集到更多的数据信息，对后期的帮助是最大的。","b":false,"xe":"So capturing high-quality source frames and gathering more data in the field helps post-processing the most."},{"t":"h","x":"2","xe":"2"},{"t":"h","x":"锐化和降噪的顺序","xe":"The Order of Sharpening and Noise Reduction"},{"t":"p","x":"降噪主要在第一步做，锐化主要在最后一步做。","b":false,"xe":"Noise reduction mainly happens in the first step; sharpening mainly in the last."},{"t":"p","x":"因为ACR和Lightroom中的调整，顺序是无所谓的。所以一般我会在ACR最后的时候，给照片初步降噪。","b":false,"xe":"Since the order of adjustments inside ACR and Lightroom doesn't matter, I usually do a preliminary noise reduction at the end of the ACR stage."},{"t":"img","f":"img-08","w":1000,"h":767},{"t":"p","x":"进入PS后，第一步就是用Nik Dfine插件，对照片进一步降噪。","b":false,"xe":"Once in Photoshop, the first step is further noise reduction with the Nik Dfine plugin."},{"t":"img","f":"img-09","w":823,"h":800},{"t":"p","x":"有时在PS中进行更多调整之后，原来不明显的噪点凸显了出来，这时输出前还可以降噪一次。因此我前面说降噪“主要”在第一步做。（关于降噪，请阅读《三步降噪法，打造完美照片》）","b":false,"xe":"Sometimes, after more editing in PS, previously invisible noise becomes prominent — so one more round of noise reduction may be needed before output. That's why I said noise reduction happens \"mainly\" in the first step. (For more, read \"Three-Step Noise Reduction for Perfect Photos.\")"},{"t":"p","x":"锐化的话，对画面破坏比较大，而且主要是输出锐化，根据展示媒介和大小，锐化量天差地别，因此主要是最后一步做。","b":false,"xe":"Sharpening is more destructive to the image and is primarily output sharpening — the amount varies wildly with the display medium and size — so it mainly happens in the last step."},{"t":"h","x":"3","xe":"3"},{"t":"h","x":"多步少量原则","xe":"The \"Many Small Steps\" Principle"},{"t":"h","x":"宁可分多步骤每步少量调整，也不要尝试一次到位。因为：","xe":"Better to adjust in many small steps than to try landing it in one go, because:"},{"t":"p","x":"1）后期很多时候是主观感觉，很难一次精准到位。调的不够，后面再加就是了。但是如果不小心调过了，比如把饱和度一下改变太多，加了又减损失更大。","b":false,"xe":"1) Post-processing is often a subjective judgment, hard to nail precisely in one pass. If it's not enough, add more later. But overshoot — say, pushing saturation too far — and backing it off costs you more."},{"t":"p","x":"2）不同工具和步骤之间是互相影响的。比如在RAW文件中，如果饱和度调的太高，后面加曲线、对比等等调整又会增加不少饱和度，再做一些可选颜色，可能红色就直接过饱和溢出了。。。","b":false,"xe":"2) Tools and steps interact. In a raw file, for instance, if saturation is set too high, later curves and contrast adjustments add yet more saturation; a round of Selective Color on top might push the reds straight into clipping..."},{"t":"p","x":"所以开始的时候对比度，饱和度，清晰度这些都不要调太猛。微微处理一下即可，后面再一步一步优化。","b":false,"xe":"So at the start, go easy on contrast, saturation, and clarity — a light touch is enough. Optimize step by step afterward."},{"t":"h","x":"4","xe":"4"},{"t":"h","x":"尽量使用非破坏性调整","xe":"Use Non-Destructive Adjustments Wherever Possible"},{"t":"p","x":"凡是只记录结果像素的修改，都是破坏性调整，要尽量避免、或者放到比较靠后的步骤。","b":false,"xe":"Any edit that records only the resulting pixels is destructive — avoid it, or push it to the later stages."},{"t":"p","x":"比如你直接在背景图层上增加100对比度，就是破坏性的调整，后面觉得不好，就只能在图层上又减少对比度，这就是非常伤画质的动作。","b":false,"xe":"For example, adding +100 contrast directly on the background layer is destructive; if you later dislike it, your only option is reducing contrast on that same layer — a very quality-damaging move."},{"t":"p","x":"更好的方式是用调整图层或者智能对象，这样你的对比度调整结果，是以原始数据+调整过程的形式储存的，觉得不好直接撤销中间的调整过程就可以了。","b":false,"xe":"The better way is adjustment layers or smart objects, where your contrast change is stored as original data plus an adjustment process; if you dislike it, simply undo that intermediate step."},{"t":"p","x":"以下都是非破坏性调整的形式：","b":false,"xe":"The following are all forms of non-destructive adjustment:"},{"t":"p","x":"1）Adobe Camera Raw、Lightroom中的调整，都是非破坏性的。","b":false,"xe":"1) Adjustments in Adobe Camera Raw and Lightroom are non-destructive."},{"t":"p","x":"2）智能对象上的调整和变形。","b":false,"xe":"2) Adjustments and transforms applied to smart objects."},{"t":"p","x":"所以ACR进PS的时候，最好按住Shift键以智能对象，而不是背景图层的方式打开。多个图像合成的时候，最好把这些图层用智能对象封装起来，而不是用盖印图层。。","b":false,"xe":"So when bringing a file from ACR into PS, hold Shift to open it as a smart object rather than a background layer. And when compositing multiple images, wrap those layers in smart objects instead of stamping visible layers."},{"t":"p","x":"3）智能对象上的智能滤镜，都是非破坏的。","b":false,"xe":"3) Smart Filters on smart objects are all non-destructive."},{"t":"p","x":"比如要用Nik 插件，最好就以智能滤镜的形式应用。这样后面要重新单独调整某个滤镜的参数，都是可以的。","b":false,"xe":"If you use Nik plugins, for instance, apply them as Smart Filters — then you can go back and re-tweak any filter's settings individually."},{"t":"p","x":"4）非破坏性裁剪。剪裁图像的时候，最好不要勾选“删除裁剪的像素”。","b":false,"xe":"4) Non-destructive cropping. When cropping, leave \"Delete Cropped Pixels\" unchecked."},{"t":"p","x":"5）调整图层。要改变饱和度、对比度、颜色，最好使用调整图层，而不是直接在原图层调整。","b":false,"xe":"5) Adjustment layers. To change saturation, contrast, or color, use adjustment layers rather than editing the original layer directly."},{"t":"p","x":"6）空白、中灰辅助图层。要仿制图章、污点清除、加深减淡等等，也要尽量在新图层而不是原始图层上操作。","b":false,"xe":"6) Blank and 50%-grey helper layers. Clone stamping, spot healing, dodging and burning — do these on new layers too, not on the original."},{"t":"h","x":"5","xe":"5"},{"t":"h","x":"局部应用调整","xe":"Apply Adjustments Locally"},{"t":"p","x":"把调整限制在局部，而不是全局作用、影响到无关的区域，也可以大大提高画质。","b":false,"xe":"Confining adjustments to local areas — rather than applying them globally and affecting unrelated regions — also greatly improves image quality."},{"t":"p","x":"比如ACR中的锐化，一定要打开蒙板，不要锐化天空、水面等大块纯色区域。","b":false,"xe":"With ACR sharpening, for example, always hold Alt and use the Masking slider — don't sharpen large flat areas like sky and water."},{"t":"img","f":"img-10","w":1000,"h":625},{"t":"p","x":"降噪则反之，可以使用蒙版遮罩，只对细节少的局部降噪。","b":false,"xe":"Noise reduction is the opposite: use a mask so it only affects low-detail areas."},{"t":"img","f":"img-11","w":1000,"h":671},{"t":"img","f":"img-12","w":1000,"h":685},{"t":"h","x":"6","xe":"6"},{"t":"h","x":"使用最新技术以及专业插件","xe":"Use the Latest Technology and Professional Plugins"},{"t":"p","x":"最新技术以及专业插件，肯定算法更优异，更推荐使用。","b":false,"xe":"The latest technology and professional plugins simply have better algorithms and are recommended."},{"t":"p","x":"比如降噪，可以使用Nik Dfine 2 或者 Topaz Denoise插件，甚至ACR的降噪功能，都比PS自带的降噪滤镜要强大。","b":false,"xe":"For noise reduction, for instance, Nik Dfine 2 or Topaz DeNoise — even ACR's built-in noise reduction — all outperform Photoshop's own noise filter."},{"t":"h","x":"总结","xe":"Summary"},{"t":"p","x":"1. 前期记录更多更高质量的信息","b":false,"xe":"1. Capture more, higher-quality information in the field"},{"t":"p","x":"2. 降噪主要第一步，锐化主要输出前","b":false,"xe":"2. Noise reduction mainly first; sharpening mainly before output"},{"t":"p","x":"3. 多步少量原则","b":false,"xe":"3. The \"many small steps\" principle"},{"t":"p","x":"4. 非破坏性调整","b":false,"xe":"4. Non-destructive adjustments"},{"t":"p","x":"5. 局部应用调整","b":false,"xe":"5. Apply adjustments locally"},{"t":"p","x":"6. 使用最新技术以及专业插件","b":false,"xe":"6. Use the latest technology and professional plugins"},{"t":"p","x":"欢迎关注@Thomas看看世界，每周学会一个摄影技能。","b":false,"xe":"Follow @Thomas Chu Photo, and learn one photography skill every week."},{"t":"img","f":"img-13","w":640,"h":313}],"titleEn":"How to Preserve Maximum Image Quality Throughout Post-Processing"}