Inbetweening

• 1. The Pencil And The Light Table

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  Dick Huemer developed a system for inbetweening during the 1920s that changed how animation studios operated. This method relied on a light table to draw pencil and paper sketches with precision. A primary artist would first create key frames to define the movement of a character or object. After testing and approval, the scene moved to assistants who performed clean-up work. These assistants added necessary inbetweens to smooth out the motion between the main drawings. In large studios, another layer of detail called breakdowns defined the movement more thoroughly before reaching the final stage. An assistant known as an inbetweener then completed the entire animation sequence. Art Davis is said to be the first person to hold this specific title within the industry. Small teams often skip these layers and have animators handle the full process themselves.

• 2. On Twos And On Ones

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  Fantasmagorie released in 1908 stands as widely considered the first fully animated movie using frame rates on twos. Most movements require only twelve drawings per second rather than twenty-four to maintain the illusion of motion. Animating on ones means creating twenty-four drawings for every single second of film length. Very fast movements demand this higher frequency while slower actions might use four drawings per second. When the number of in-betweens drops too low, the animation begins to lose its sense of fluid movement. Computer-generated animation usually operates on ones to ensure maximum smoothness. Frame frequency varies depending on the chosen style and remains an artistic choice for creators. A character in a panning shot might move on twos while background elements shift every frame on ones. Optical effects like motion blur can simulate the appearance of a much higher frame rate without extra work.

• 3. Software Interpolation Tools

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  Adobe Flash emerged in the late 1990s as one of the earliest software programs utilizing automatic interpolation. Cambridge Animation Systems developed Animo around the same time to handle sophisticated digital transitions. Tweenmaker arrived later around 2006 to offer additional options for automated tweening processes. Sophisticated animation software allows animators to specify objects within an image and define their movement paths. The program may render transitional frames manually or automatically interpolate graphic parameters between keyframes. Synfig stands out as a free software program that specializes entirely in automated tweening capabilities. Digital contexts often shorten the term inbetweening to simply tweening for efficiency. The resulting sequence of frames is called a tween by professionals working with these tools. Manual adjustment remains possible even when automatic rendering handles the bulk of the work.

• 4. The Academy Award Winners

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  Nestor Burtnyk and Marceli Wein worked at the National Research Council of Canada during the 1990s. Their pioneering work involved developing software techniques specifically for computer-assisted keyframing character animation. This collaboration earned them a Technical Achievement Academy Award in 1997 for their contributions. They enhanced the use of computers for inbetweening through innovative algorithmic approaches. The award recognized their ability to streamline complex animation tasks using digital assistance. Their methods allowed animators to focus more on creative decisions rather than repetitive drawing tasks. The National Research Council provided the environment where this technical breakthrough occurred. Their legacy persists in modern software that automates many aspects of frame generation today.

• 5. Ease In And Ease Out Physics

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  An ease-in transition starts an animation slowly before progressively getting faster as it continues. An ease-out transition does the opposite by starting quickly but then slowing down toward the end. These parameters define the physics of the transition between two distinct animation states. Linearity describes how straight or curved the path appears during the movement process. Digital animation uses these mechanisms to mimic real-world physical forces like gravity or momentum. A ball rolling across a screen might accelerate initially and then decelerate due to friction. Animators adjust these values to create specific feelings of weight or speed within a scene. The mechanism controls the linearity of a tween without requiring manual redrawing of every frame. Modern tools allow precise control over these timing curves to achieve desired visual effects.