CamCyclopedia
Contents
1. What is Log video?
2. Features of Samsung Log
1) Implementation of Wide Dynamic Range
2) Rich and free color expression
3) Provision of optimized LUT
4) 10bit HEVC codec
3. Samsung Log support details
1. What is Log video?
When light entering the camera lens is detected by the sensor, the amount of light received is digitized and recorded through the image processor. However, cameras and the human eye perceive light differently. Cameras measure the absolute amount of light, while humans perceive the relative amount of light. The human eye can perceive small changes in the dark, but it can only perceive changes in the light when there are larger changes. For example, think about when you light a candle in a dark space and a candle in a bright space, as shown in the picture below.
Cameras use linear calculations to perceive the same amount of change in luminance, but the human eye is nonlinear and perceives luminance changes in dark areas more sensitively than in bright areas, even when the same amount of light changes. If the brightness of the scene detected by the sensor is linearly reflected in the camera pixel values, the dark scene will not show the subtle changes in brightness that humans perceive, and the bright areas will show differences that are barely perceptible to the human eye, resulting in inefficient use of limited data. Log video technology is designed to solve these problems.
Log video is a technology that allows a camera to mimic human visual characteristics. The goal of Log video is to maximize the gradation of dark areas of a video image and reproduce a wider dynamic range. The linear data of light recognized by the camera is converted to a Log scale by applying a gamma correction value. The amount of scarce data in the dark areas is increased and the amount of unnecessary data in the bright areas is reduced. By increasing the data in the dark area, a wider dynamic range can be expressed in the image. However, as the brightness of the dark area increases, the contrast of the image decreases, resulting in a blurred image. This may cause the original image to appear washed out, but this is to provide a high degree of freedom in image editing. For example, a drawing that has been sketched and colored has many limitations in changing the color, but in a drawing with only a light outline, you have much more freedom in expressing your own color and style. Therefore, by using Log video, you can create a video with the colors you want by extensively correcting the colors, exposure, and contrast of the original video.
2. Features of Samsung Log
Samsung Log maximizes the benefits of Log video through the following features.
1) Implementation of Wide Dynamic Range
Samsung Log is designed as a curve that combines the Log function and the S-shape to minimize the loss of contrast in dark areas while simultaneously obtaining rich gradations. In the figure below, you can see that in the top graph, the 10-bit pixel values increase in a Log curve shape as the Scene Reflection increases. The bottom graph shows an S-curve in the dark area, and it is able to express the contrast of the dark area well by preserving the tone gradation in the darkest part.
2) Rich and free color expression
Images shot in Samsung Log have a color space defined in ‘ITU-R Recommendation BT.2020’, a color space standard for broadcast videos established by the International Telecommunication Union (ITU). As you can see from the graph below, videos shot in Samsung Log have a wider color space than sRGB or DCI-P3, which are widely used in TVs and monitors. Since the original data contains many colors, users can express rich colors as they want through lossless data utilization in post-color correction.
Samsung Log provides an optimized LUT (Look-Up Table) to express accurately the colors of images shot in the BT.2020 color space in BT.709, a standard color space developed by ITU-R. With excellent LUTs that require no further editing due to its natural and clear color expression, you can adjust the tone and mood of your images, as you desire, more easily. You can edit using LUT by either of the following methods.
- Mobile Editing: You can convert them to standard color using the Edit Suggestion option in the Gallery app. You can also adjust the brightness, contrast, colour, and apply filters through Video Editor, if further editing is necessary.
- PC Editing: You can download Samsung Log’s LUT from the Samsung Developer Portal, and can edit the video precisely using a PC Editor such as DaVinci-Resolve or Premiere Pro. There are two types of LUT available: 1D LUT and 3D LUT
4) Codec compatibility and optimized storage
Samsung Log uses the 10-bit HEVC codec to provide excellent accessibility in terms of codec compatibility and storage. This allows professionals to experience high-quality Log video shooting that is comparable to professional shooting equipment, while general users can experience easy-to-use Log video shooting.
3. Samsung Log Support Details
Support Information | Samsung Log |
Supported device | Galaxy S25/ S25+/S25Ultra |
Resolution | All rear camera resolutions 8K30, 8K24, UHD120, UHD60, UHD30, UHD24, |
Codec | 10bit HEVC (Up to 140Mbps in 4K) |
Mode | Pro Video mode Video mode (the Log option needs to be enabled in Camera settings) |
Lens | All rear camera lenses (UW, W, T, ST) |
Pro Video mode filming options | Manual controls Exposure monitor (Zebra pattern, False color) |
Storage options | Option to save in external storage (SSD) ※ The option is supported via the Camera Assistant app |
※ The aforementioned details concerning eligibility criteria, features, and/or other relevant matters, may be subject to modification in accordance with Samsung's policies.
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