一張影像拍攝的成功與否最重要的觀察點是影像的亮暗分佈及細節而非色彩，也就是由最暗到最亮部分的灰階是否平滑及呈現細節，然後由安裝在相機感光裝置上的彩色濾片依光現亮暗的程度轉換成彩色影像，因此一張漂亮的照片須從正確的曝光獲得，也就是能呈現愈多的由暗到亮完整的灰階。

We see a pretty photo that amaze us is because of its tonal value i.e. it’s bright and dark map but not its colors, that is the displaying of the dark to the bright zones have a smooth steps and details, and the color which we see is coming out from the color filters in front of the camera sensor according to the tonal value captured by the camera. But a pretty color photo will not only come from a more zones of bright and dark tonal value during the camera capture but also the  color consistency .

最近在整理一些我過去幾年旅遊的影像包括北美和挪威北極等地區，主要整理一些風景的影像，將這些影像以一種更細緻的風貌呈現，過去在Lightroom的後製修飾其實已有很多功能可運用，使影像呈現更多元更藝術化的內容，來彌補拍攝時相機記錄的不足(包括曝光、色彩、白平衡等)，Adobe Lightroom 是 Adobe公司發展的軟體提供職業攝影師以簡潔、快速的程式來達到處理大量影像的目的，最新版本更提供不同的筆刷局部修飾功能，使攝影師發揮創意修飾出更吸引人的影像，Adobe Lightroom是對整張影像的修飾有其速成的效果，但影像內個別”畫素”(Pixel)的顏色深淺和光線強弱、對比等等只能做一種總和式的調整，其中如色彩的調整無可避免的會影響亮暗對比，相同的如光線亮暗的調整也會影響色彩的飽和等，因此在整理過去影像的過程中，發現有些影像畫面應能更進一步展現其拍攝當時視覺上的實際色彩和明暗狀況，此時就須思考對影像中每個畫素(Pixel)的修飾，因此本篇的內容將說明以Adobe Photoshop 的Lab色彩模式即”色彩及明暗分離“的方法來修飾，展現出更精緻美麗的影像內容，其中的技巧包括Lab色域、色彩混和合器、圖層混合器及亮度/色彩圖層混和器等。

Recently I worked on some images that I took  some years ago during my travels, they are mainly the landscape images, to give those photos more delicate appearance, although the post processing in Lightroom make them already turning out to be in a good form which compensates the deficit from the camera capture (such as exposure、colors and white balance etc.),  Lightroom is an image fixing software of Adobe which can be easily managing a great amount of images in a short time, including category and development of the images adapted by many professional photographers, the current edition Lightroom CC providing some advanced function like radial graduating and local adjusting brushes, that photographer can be more creative in the post processing work flow. For already proper exposure images it will be quick and easy to adjust and fix, becoming more effectively in handling great amount of images, but for the tonal value and color contrast between pixels, the adjustment in the Lightroom can run into an interfere between tonal value and color contrast, for example when adjusting tonal value might increase or decrease the color contrast, on the contrary, when adjusting color contrast will also interfere the tonal value become darker or lighter, for a better enhancing those images which can be more reflecting the true tonal value and color contrast on the scene, we need to improve them by pixels in Photoshop, now I would like to explain in this blog about how to use Photoshop “Lab” trick to separate the tonal value and color contrast when enhancing, it includes” Lab color mode”、”channel mixer”、”layer blending modes” and” layer style blending option”etc..