How to realize film-level color matching of photos

Many movie friends like the color of movies very much, and hope that digital photos can also be colored according to the method of movies, so as to obtain a wider dynamic range of color matching. Nowadays, with the development of technology, through the file mode conversion and software control in Photoshop, you can easily achieve movie-level color matching, so that your photos can get more shocking and advanced color performance.

To achieve film-level color matching of photos, simply put, it is to convert Raw into LOG mode and then load 3D LUT files. The following briefly introduces the technologies and concepts in movies such as LOG mode and 3D LUT, and demonstrates the specific application in Photoshop through cases.

About log mode

The digital negative of a digital SLR camera is a file in Raw format. Although the tolerance of SLR camera Raw is very high, it is presented to users in sRGB/Adobe RGB color space, so the photos taken by Raw are no different from JPG directly from the camera if they are not processed.

By contrast,

Digital video adopts LOG mode, which is a matching format between movie platforms. It uses a flat LOGarithmic curve to represent data, so it is called log because its shape is similar to a logarithmic function. Due to the log

The color space of the camera is very large, and the tolerance is correspondingly increased, which can give full play to the dynamic range of the camera. Now almost all professional cameras use log mode to shoot high-quality images, but the shooting of SLR cameras

Log mode is not supported at present.

Log "flattening" the image information taken by the camera has the characteristics of "full dynamic range" recording. Therefore, the log image will look gray and flat, but it contains and records rich light and dark details. Make good use of it

Log image, which shows the same effect as film, must be colored on the basis of gray image, so log material must be equipped with LUT to display and color film correctly.

Original film shot by SLR camera

Convert to logarithm (the image becomes gray and flat, and the light and dark levels come out)

The effect of loading 3D LUT into color in movie mode.

About 3D LUT

LUT is looking up.

The abbreviation of Table means "lookup table". When you open the LUT file with a text editor, you can see that LUT is just a set of digital tables, which represent the original value of RGB and the target value of mapping.

That is, the color of the original image is mapped to the new color. Essentially, the function of LUT is to convert the input values of each group of RGB into output values, while the data of RBG are independent of each other.

Because the color control function of one-dimensional LUT model combination will still have some limitations, which will only affect gamma, RGB balance (gray scale) and white field, so accurate color control is most often used in three dimensions.

LUT(3D LUT) can accurately convert the input data of each image pixel and give consideration to the simulation of aesthetic quality, so it can realize the control of full stereoscopic color space. Three-dimensional (abbreviation for three dimension)

There are RGB channels in each coordinate direction of LUT, which makes it possible to map and process all color information, and even reach the color gamut that cannot be displayed by film.

How to realize film-level color matching of photos

Through the study and preparation of the color matching technology in the above-mentioned movies, the purpose is to make photos can also be loaded with 3D LUT in Log mode for color matching, so as to realize the color matching of photos in film industry! All these can be realized in Photoshop. Let's explain the steps and methods in detail through a case demonstration.

Usually, the color space of film is LOG logarithmic space, and it can only be displayed correctly if LUT is loaded. Many digital cameras don't have log preset files, even in 3D.

LUT file can't realize so-called movie color matching. Therefore, the premise of digital photo simulation film color matching is to convert the digital negative in Raw format into Log mode. The conversion from Raw to LOG is

Convert the color matching method of camera photos into the color matching method of movies. After Raw is converted to LOG mode, Photoshop can also load 3D.

LUT has entered the film-level industrial color matching process!

first step

Before we begin, we need to find the digital classroom of mass photography from www.gogoup.com, and then download the materials to find the "VisionLOG" folder, which contains some camera LOG.dcp files. Unzip to get the "VisionLOG" folder.

Second step

Users using Mac OS system, copy this folder to.

HD:/User/your username/Resource Library/Application Support/Adobe/camera raw/camera profiles

Users using Windows system can copy to C:/users/yourusername/appdata/roaming/Adobe/cameraraw/camerafiles.

Third step

Select a picture file in Raw format in Bridge. Open it in Camera Raw, and select the color depth as "16 bits/channel" in the workflow window to make the photo have a larger dynamic range.

Fourth step

Under Camera Calibration, in Camera Profile, select the "VisionLOG" just imported. At this time, you will find that the photo becomes very gray and flat, the saturation and contrast are reduced, and the highlights and dark parts have generated a very rich layering. Log format conversion succeeded.

Step five

Click Open Object in Camera Raw to open the photo in Photoshop. Select Color Lookup in the Layers panel Create New Fill or Adjust Layer to open the Color Lookup Properties panel.

Step 6

Select the LUT preset file in the color search 3D LUT file. Photoshop CC20 14 comes with some preset files by default, and you can see different tone effects by switching and selecting.

Step 7

Choose the most suitable 3D LUT preset for this photo to get the final effect. In this way, the Raw format photos loaded with LUT can be colored in the form of movies.

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