This is an ongoing article that will be continuously updated. Its content will expand and evolve as my learning progresses. The purpose is to help myself summarize what I’ve learned about photography, color grading, and editing, while also sharing these insights with you.

As someone with zero foundational knowledge but a deep passion for recording the world through a lens, I hope to approach photography and post-production with the same attitude I had when I took my first steps toward becoming a music producer. I intend to keep learning, practicing, and making infinite progress.

Regarding the hardware and software I currently use:

  • Shooting device: iPhone 17 Pro Max
  • Camera apps: Blackmagic Camera / Hurricane Camera (飓风相机)
  • Gimbal: DJI Osmo Mobile 8
  • Post-production machine: Mac Studio
  • Software platforms: DaVinci Resolve / Final Cut Pro

For now, my priority is to focus on mastering video shooting with my phone. Once I can consistently produce decent work, I will consider buying a dedicated camera to further explore this field. The primary reference for the information in this article is the course by Media Storm (影视飓风): “Watch Just 8 Lessons to Shoot Cinematic Footage with an iPhone”. For some extended concepts, I also use generative AI tools like Gemini to assist my learning. I manually cross-check and verify the information provided by the AI to ensure accuracy as much as possible. If you spot any oversights, please kindly point them out, and read critically.

If there are any new sources of information in the future, I will declare them at the beginning of the article.

Prerequisite Basic Knowledge

Data Types and File Formats

Let’s first look at a simulated conversation.

In the editing room, the director says to the colorist:

“The ‘Camera A’ footage is ProRes RAW, and the ‘Camera B’ footage is 10-bit Log. First, apply that LUT to all the Log footage to convert it from the Log space to Rec.709, so we can see the normal colors.”

After the colorist does this, the director frowns: “It’s too clean. Swap the ‘Camera B’ footage with ProRes 422 proxy files, and we’ll start editing. Once the edit is locked, slap that ‘film simulation’ creative LUT on it so we can see the stylized effect.”

After the edit is complete, the colorist says: “I will export the final master as ProRes 4444. For the client preview, I’ll compress a 50Mbps H.265 file, and I’ll also render a separate H.264 version for better compatibility.”

  1. What is a LUT?

LUT stands for Look-Up Table. In video shooting and post-production, a LUT is essentially an “instruction manual” or a “preset” for color conversion. It plays two key roles in the video workflow: translating the “flat” or “gray” original Log footage captured by the camera into a standard color image that a monitor can display properly, and applying a specific color recipe on top of that standard image to give it a desired cinematic feel or artistic style.

You can think of it as an extremely precise, advanced filter. It defines exactly which output color a “specific input color” should be converted to. Rather than simply overlaying a visual effect, it performs a precise mathematical mapping of the color values of the pixels in the video.

There are two main types of LUTs: 1D LUTs and 3D LUTs. A 1D LUT is relatively simple; it can only independently control the red, green, and blue (RGB) channel values and cannot accurately handle complex combinations of different saturations and hues. A 3D LUT is the most common and powerful type used in the video industry. It uses a three-dimensional color cube to map colors, allowing it to simultaneously control Hue, Saturation, and Luminance for incredibly complex and precise color conversions. For example, it can strictly dictate: “convert all low-saturation greens in the image into high-saturation cyans while keeping the brightness exactly the same”—something a 1D LUT simply cannot do.

  1. What is Log?

Log is a gamma curve (Transfer Function) used to encode light, and its primary purpose is to compress the dynamic range. More specifically: within a limited data space, it compresses the linear light energy distribution captured by the sensor so that the highlights don’t blow out and the shadows don’t crush, thereby recording the widest possible dynamic range. “Log” mainly refers to this logarithmic curve, but it is usually combined with a brand’s specific color matrix to form a complete Picture Profile. The logarithmic curve is designed to “compress” highlight data into limited bit values to expand dynamic range. Raw footage shot in Log looks “flat” and “gray,” requiring post-production color grading to restore contrast and saturation, and to apply stylization. Most mainstream camera brands have their own unique Log formats optimized for the characteristics of their specific sensors. There is no unified standard among different companies’ Log implementations, making them incompatible with one another.

Here, I will specifically mention Apple Log, which I will be using. It is only available in the iPhone’s ProRes mode (the ProRes 422 series). The standard HEVC format does not support Apple Log.

  1. What are RAW, ProRes, and H.264/H.265?

RAW is a data type, though different manufacturers use different RAW formats. All RAW files are “digital negatives,” but the composition and the way each negative is “developed” vary. RAW represents the sensor’s pixel-by-pixel sampled electrical charge readings, typically as single-channel Bayer Pattern data. RAW files must undergo a process called “Debayering” (or “development”) before they can be translated into the color images we see. RAW offers immense flexibility in post-production. It allows you to freely adjust exposure gain and white balance after the fact. However, because it is raw data, the file sizes are massive, and it requires a highly capable computer to “develop” the data in real-time.

ProRes is a codec designed to compress “already-formed” images. While the default H.264/H.265 files output straight from cameras are small, they are compressed too “aggressively” (using Inter-frame compression). During computer editing, these files must be constantly “decompressed” on the fly, leading to poor performance and stuttering. ProRes uses Intra-frame compression; the compression ratio is much lower and the files are much larger, but it makes editing incredibly smooth. Its core value is to ensure editing performance. ProRes (4444/422) files store images that have already been “developed.” The camera’s white balance, ISO, exposure, and Log curve (such as Apple Log or S-Log3) are already baked into the image. You can color grade ProRes (Log) files, but you cannot “develop” them like RAW files, meaning you cannot losslessly change the white balance in post. Note: ProRes RAW is different from standard ProRes; it contains RAW sensor data, not “developed” image data.

H.264 stands for Advanced Video Coding (AVC), and H.265 stands for High Efficiency Video Coding (HEVC). They are currently the most popular and widely used codecs in the world. Their core objective is to make video files as small as possible while retaining high image quality, making them ideal for storage and internet streaming. H.265 utilizes a more advanced compression algorithm than H.264. At the same visual quality settings (PSNR/VMAF), H.265 can save roughly 30–50% in bitrate compared to H.264.

  1. What is Rec.709? And what concepts are related to it?

The official name of Rec.709 is ITU-R Recommendation BT.709, a unified standard for high-definition television. It primarily defines the Color Gamut and the Gamma Curve. Rec.709 is one of the standard color spaces for SDR (Standard Dynamic Range). The concept of SDR encompasses color spaces (like Rec.709), the EOTF (BT.1886), and specific brightness standards.

In contrast to SDR, HDR (High Dynamic Range) is an umbrella term for a series of new technologies aimed at surpassing SDR standards to create more realistic images that closer mimic what the human eye actually sees. For instance, the reference peak brightness for BT.709 traditional SDR is around 100 nits, whereas HDR displays can reach 1000 nits or even higher. HDR also utilizes a much wider color gamut, primarily Rec.2020. All HDR content must have a color depth of 10-bit or higher (e.g., 12-bit). This means HDR can display a vast array of highly saturated colors—like Ferrari Red, Coca-Cola Red, or vivid neon greens—that Rec.709 simply cannot accurately reproduce. However, since many physical displays cannot fully cover Rec.2020, the actual color gamut coverage of most consumer HDR screens is closer to DCI-P3.

Breaking down the main “factions” of HDR, they utilize different EOTFs. Here are three primary HDR standards:

  • HDR10: A basic, universal open standard that allows you to set a single “maximum brightness” for the entire video.
  • Dolby Vision: Dolby’s proprietary standard that allows you to adjust HDR metadata on a scene-by-scene, or even frame-by-frame basis.
  • HLG (Hybrid Log-Gamma): A standard specifically designed for television broadcasting (such as live sports).
  1. Connecting the Concepts

From shooting to the final export, the concepts above interact throughout the workflow:

  • Capture: Shoot video using a device that supports Log.
  • Editing: You can transcode the Log footage into ProRes for smooth editing.
    • If you are using Apple Log, the capture is already encapsulated in the ProRes codec, so no transcoding is needed.
  • Delivery: Choose between SDR or HDR.
    • If SDR is chosen: The 10-bit Log footage is “compressed” through a LUT, discarding the extensive highlight and color information held in the Log profile, keeping only what fits inside the “small box” of Rec.709. The final export is an H.264 (8-bit) file, making it highly compatible for playback on any device.
    • If HDR is chosen: The 10-bit Log footage is color mapped to HDR10 or Dolby Vision standards during grading. The expansive highlights and broad colors recorded in the Log are retained. The final export is an H.265 (10-bit) file intended for viewing on HDR-capable displays.

Basic Concepts of Brightness

The human eye can rapidly adapt between extreme light and extreme darkness, but cameras cannot. Cameras can only accommodate a limited range of brightness, known as Dynamic Range.

A larger dynamic range means there is a wider “accommodating distance” between the brightest recordable detail (before it blows out) and the darkest recordable detail (before it crushes to black).

If the light exceeds this range, the image will exhibit the following issues:

  • Overexposure / Clipping (Highlights blowing out)
  • Crushed Shadows (Shadows turning into pure, dead black)

The brightness perceived by the camera is the combined result of the Aperture, Shutter Speed, and ISO.

  • Aperture
    • The size of the lens opening. The larger it is, the more light comes in.
  • Shutter Speed
    • The duration of the exposure. The slower it is, the more light comes in.
  • ISO
    • The sensor’s “gain” sensitivity to light. The higher the ISO, the brighter the image, but the more digital noise is introduced.
    • If the brightness exceeds what the camera can handle, the image will “blow out.”
      • Each pixel on the sensor can only record a certain maximum electrical charge.
      • Once this limit is exceeded → the charge overflows → the pixel becomes pure white → Clipping occurs.

Some cameras offer features to warn you when overexposure is about to occur, such as:

  • Zebra (Zebra Pattern)
    • When the brightness of a specific area in the frame exceeds a threshold you’ve set (e.g., 95%), diagonal stripes will appear over that area. It essentially acts as an overexposure warning system.
    • Zebras use IRE to determine where the brightness is too high.
      • IRE is a scale unit for measuring video brightness (0 = Black, 100 = White).

One crucial tool that helps reduce the amount of light entering the lens—without altering the colors—to avoid overexposure is the Neutral Density (ND) Filter.

(To be continued)