The colorist II. Technique and creation blended.
By CARLOS MEDINA, Audiovisual Technology Expert and Advisor
Fiction films, series, advertising, television programs, video clips, short films, documentaries and even audiovisual content for social networks in their different versions are part of leisure and (entertainment. This scenario in which we currently operate allows any image professional regarded as such -be it a colorist or not- to know how to use the possibilities offered by the various software packages available.
All these software solutions and computer applications share common knowledge and enable us by means of different tools, to modify, adjust, balance and define the visual side of things. Therefore, it is now time to go over some parameters (the ones that seem essential to me) when tackling a color correction or color grading session or, even, to be mastered before becoming a qualified colorist:
Resolution: It is the number of lines or pixels that comprise an image both horizontally and vertically (height and width). Hence, the number of lines/pixels that a space covers. That is why it is also known as spatial resolution. The higher the number of lines/pixels, the higher the level of detail, the better the image’s definition, more visual information and, therefore, the higher the quality.
It is important to be clear about this parameter because of what it currently means to share images of different resolutions in the same project. This implies different qualities and textures when working with the visual side. It is important to take this parameter into account right from the time of choosing the recording/filming camera.
Aspect Ratio: It is calculated by dividing the width by the height of the image that can be viewed on the screen and it is normally expressed as ‘X:Y’. The visual outcome depends on the aspect ratio, therefore resulting in the so-called square images or wide-view images. Based on the origin of their respective professional environment (television broadcast or cinema) images have different proportions between width and height.
The aspect ratio in the era of SD television was until more or less 2009, 4:3, which is expressed in cinema as 1.33. High definition (FHD) images must have a 16: 9 aspect ratio (in cinema: 1.77: 1 that is 1.77 times wider than height).
Other aspect ratios used in TV/cinema at present are 18:9/2:1; 14:6/2.35:1; 11:4/2.76:1, and even 360° all-round vision (12.00:1 in cinema).
In some instances, this parameter receives the name of dimensional relationship, often called aspect relationship, aspect ratio, aspect proportion or aspect rate.
Frame Rate: It expresses the number of frames per second in a moving image. Acronym is FPS. A highly relevant piece of data throughout the process, from on-camera capture to mastering for distribution within the various production environments: cinema, television, streaming and/or social media.
Luminance (Y): It is the component of the video signal that represents the information on black and white levels contained. In other words, it is the photometric measure of brightness in a video image. Therefore, it tells us white, black and gray values in an image.
It is a very technical parameter, and one that requires proper assessment in order to achieve a correct output of the master broadcast/exhibition material.
Chrominance (C): A technical term that designates and defines the color components in a video signal and contains information on the primary colors R (red), G (green) and B (blue) in additive synthesis. It is equally important as luminance (Y) for a correct technical processing of the image/video to be delivered.
Contrast: A fundamental parameter for adjusting the level of intensity between black and white in an image, by fine-tuning the values in a gray scale. Tweaking this parameter results in images that are more washed or more contrasted. It is closely related to two other concepts such as dynamic range and latitude, which are essential to take into account when choosing a type or model of video, film or TV camera.
The values that contrast can offer us allow us to generate very different visual sensations in relation to the audiovisual narrative received by viewers.
Saturation: One of the properties of color. It is the combination of light intensity and distribution of the different wavelengths in the color spectrum. It involves referring to intensity/pureness of a color. Knowing the effects when modifying saturation values of an image is key, because a highly saturated color has a vivid and intense color, while a less saturated color appears more washed out and gray.
Hue: Another of the essential properties of color. It defines the shade, the qualitatively differing aspect of the color experience that is related to differences in wavelengths or to mixtures of different wavelengths. Different tools will allow us to modify the color hue of the image and, therefore, modify the real image captured.
Brightness: Also called clarity. It is the third attribute of color. The darker the color, the weaker the brightness. This term is sometimes associated with the concept of value, luminance and/or brightness.
Along with saturation and hue, this value expresses -within the meaning of color in the aesthetics and narrative of the audiovisual work- the psychology of color and the sensations and emotions that it can cause in viewers.
Color sampling and subsampling (Chroma Sampling): is a digital video processing technique that has an impact on luminance and chrominance information. The higher the color subsampling, the higher the number of bits per color and therefore more information on the color gamut for better color correction and treatment. Its current maximum value is 4: 4: 4: 4: which corresponds to values for Y: R: G: B).
Color Depth (Bit Depth): A specified amount of binary data (amount of bits of information) to represent a color. The greater the color depth, the greater the ability to achieve realistic colors and a better color rendering. We are dealing with images/videos at 8 bits, 16 bits or higher figures when quantifying the digitization of a video signal.
Color Models: They are abstract mathematical models that allow colors to be represented in numerical form, typically using three or four color values or components. Knowing the RGB, HSL, HSV models is a must here.
Color Spaces or Color Gamut: It is a representation of a specific range of colors established within a color model. In 1931, the Commission Internationale de l´Éclairage (CIE), after various studies and experiments, laid down the rules of the color “pitch” by means of mathematical values and coordinates, in which we know as the colorimetry triangle or CIE Diagram. This diagram represents the spectrum of human vision and point D65 is the center of reference for white. Thus, each new contribution/innovation by agents in the image sector (film, television, photography, graphic arts, design, Internet…) has generated their own color space or gamut within the CIE Diagram.
It is essential to take into account this parameter since a given video material can have different color spaces depending on the regulations it is compliant with. For example, ITU-R BT709 in implementation of UHDTV 1 PHASE 1 production environments; or the P3/XYZ gamut applied in the digital cinema sector (DCI 4K/2K).
Legal range (legal signal or data video): A level established by broadcast radio and television technical standards to define the maximum and minimum level of brightness allowed in this professional environment. It varies depending on the image’s color depth.
Thus, an 8-bit encoding has a legal range of 16-235 versus a 10-bit encoding, which is 64-940.
Extended range (extended signal): A level established by digital cinema technical standards in order to limit the maximum and minimum level of brightness allowed in this professional environment. It also varies depending on the color depth of the image.
In this case, an 8-bit encoding has an extended range of 0-255 versus a 10-bit encoding, which is 0-1023.
Gamma Curves: The level of response of the image obtained in camera for a better adaptation of midtones in the video signal. The heyday of color grading arises when logarithmic curves are made available at shooting. This results in a low contrast, washed out image, but with a greater dynamic range and requiring subsequent correction. Thus, the main broadcast camera or digital cinema manufacturers generate their own curves: CANON C-Log, C-Log 2 and C-Log3; Cine-like, V-log and PanaLog from PANASONIC; SONY S-Log, S-Log2 and S-Log3; RED ONE’s RedLogFilm; ARRI’s Log C or BLACKMAGIC’s Film Mode among others.
Metadata: The information that is available from a video clip taken from the camera. They can be structural or descriptive. The former are an essential part of the entire visual treatment process carried out on the resulting image, especially when working with a RAW video format.
RAW: Like its own name suggest this is a term used to name the very data of the digital file that is generated in the image/video as captured by the video, cinema and/or photography camera’s digital sensor.
Workflows: this aspect is already familiar to everyone coming from the worlds of video editing and post-production. It involves knowing all the possibilities that exist throughout an audiovisual production to reach a broadcast or exhibition master. It is essential to know how to handle file exchange protocols such as: EDL, XML, AAF.
LUTs (Look Up Tables): These are table-like files with values that modify our input colors (camera material) n order to achieve a specific output (what we see on the screen), thus allowing us to modify the colors in a color grading session. There are two kinds: LUT 1D and LUT 3D. The difference lies in the accuracy of the color transformation and the number of colors can be described between them.
Without a doubt, there are more concepts, terms, processes and protocols that must be handled by any colorists who want to show their mettle in the audiovisual industry. In this sense, it is essential to know the image/video analysis tools, known as scopes:
Waveform Monitor (WFM): It allows displaying the values of the video signal that correspond to measurements in volts and/or IRE (or in percentages) for the luminance parameter.
Vectorscope: A tool for measuring chrominance information values in a circular graph. Both in the angle of the vector -being the hue- as in its length, related to the saturation of each color wavelength found in the image.
RGB Parade: It presents the waveform information for the RGB channels separately and in parallel for a better comparison of levels on channel.
Histogram: This is a tool that allows viewing the distribution of the amount of information contained on each RGB channel in terms of dark, medium and high-light areas. That is, a map of tonal RGB values in reference to the measurement of the real exposure made in the take of the recording/filming process.
These scopes are key, because each one presents us with objective technical data contained in the video signal and, therefore, they are the best “X-ray” depicting errors/hits offered by the image/video. These tools can be found in a myriad of applications and programs used for correction, color grading, editing, post-production, composition and visual integration.
To finish this article on the figure of the colorist, let’s try to classify the modus operandi of the colorist when approaching a routine in his color room; the room or facility where it seems that magic makes -visually speaking- “almost everything” possible:
1. Calibrate and fine-tune the room’s equipment.
2. Analyze the received video material in a first viewing.
3. Classify and sort out the material based on the adjustments to be made.
• Global adjustments: Those that address image adjustments in a broad sense, as a whole, and allowing for correction of specific technical parameters (gain, range, saturation, color temperature, dynamic range …). They are modified with tools like color wheels; vertical sliders (primaries / RGB mixer), horizontal sliders, edit or numeric boxes, curves, 3-way color, levels…
• Range settings: applied to “tackle” certain ranges of color in images. They allow stressing, modifying or decreasing color in areas of an image. Qualifier is one of the tools used for this task.
• Selective adjustments: these adjustments allow you to isolate parts of an image where the relevant corrections are to be applied. The relevant tools are the masks, windows, shape tools, key, alpha channel, shapes.
• Metadata settings: This deals with the structural and descriptive data that come from a RAW camera.
• Tracking adjustments: They allow working with adjustments on the moving image. They are the trackers.
• Positioning adjustments: They refer to reframing, rescaling, rotations, etc. Tools like sizing, pan, zoom, tilt, rotate, transform…
• Filter and effect settings: These are the settings that are included by the software’s manufacturer or by some developer of plugins. The Da Vinci Resolve PowerGrade are well known, but in this section we are including all those such as sepia, vintage, B/W, posterize.
• Presets: Changes that are made with looks and LUTs, both generic (filmstock, looks camera patches, cine looks, style) as well as standard (encoding color, 709, sRGB, DCI/ P3 …) and custom (settings look). And the procedures that allow adjustments with the video card reference in the take (Color Match).
• Special settings: correction solutions for very specific areas such as stereoscopic images, lens corrections and implementation of the different HDR variants (in the not too distant future it will be essential to know how to work with moving HDR images).
• Output setting (deliver): Knowing the output settings to gear and finish our work. Output formats: frame sequence, AVI, Quicktime or MOV. And output files /codecs: Kodak Cineon, SMPTE DPX, CinemaDNG, Cinepack, DV, Cineform, H261, H263, H264, JPEG 2000, PNG, TGA, AJA Kona, Apple Uncompressed, Blackmagic, etc.
In all this learning and professionalism in being or becoming a colorist, we cannot miss the reference of the Academy Color Encoding System (ACES), created by the Hollywood Academy of Motion Picture Arts and Sciences). ACES is a proposal for color management throughout a film or television production: from capture, to editing, through VFX, grading, mastering, archiving and any future remastering work.
In the audiovisual sector we can find basic tools to start practicing as a colorist in software applications specializing in video editing (Final Cut by APPLE, Premiere CC by ADOBE, Media Composer by AVID or Vegas by SONY). Also, at a higher level, Lumetri Color by ADOBE or the Magic Bullet Suite plugin by RED GIANT.
Advanced and highly-specialized solutions are DaVinci Resolve from BLACKMAGIC, Assimilate Scratch, Rio from GRASS VALLEY, Mistika from SGO and Base Light from FILMLIGHT.
2021 will see the first edition of the FilmLight Color Awards. Wolfgang Lempp, CEO of FilmLight, comments: “We believe that, for all sorts of historical reasons, colorists don’t always get the recognition they deserve. As part of our responsibility and commitment towards the industry and our customers, our goal is to remedy this by means of these awards”.
The program presents four categories: colorist in a motion picture released in theaters, colorist in a production not released in theaters or in a television series, colorist in advertising or music videos, and the award for the most innovative use of technology aimed at achieving a creative result.
These awards, as an example, and the continuous recognition that the audiovisual industry is giving to color grading are the result of a balance between technique and creation in the hands of the colorist.