Rendering – the final step in image and video processing

From design and photography to film technology – there is no getting around rendering when digitally processing objects, images and films. Rendering is especially important in graphics production, image and video editing. It is the final, key step before completion, during which a file is transformed into a finished image or video.

The reason for this is that the objects you work on are first stored in a compressed file format to make them quicker and easier to edit. Specific image properties – like colour gradients, shading, depth of field and more – are only added right at the end. This step is called rendering.

Put simply, rendering refers to the conversion of pre-programmed or recorded datasets into two or three-dimensional images. During an intensive computational process, specific properties are conferred to the raw data. The result is an image format displayable on computers and other digital devices, which is reproduced with all defined specifications.

Depending on how detailed the data describes the subsequent image, rendering can take a considerable amount of time. Moreover, it demands peak performance from the computer. Particularly in the case of video editing, which involves not just a single image but a whole sequence of images, rendering is a time-consuming process. The higher the performance of the computer or individual components like the CPU or the graphics card, the less time it takes.

What exactly happens during rendering depends on whether a digital object, a photo or a video is rendered. For this reason, it makes sense to answer the question “What is rendering?” separately for each of these areas.

When creating a film or video sequence, the various layers such as image, audio, text or graphics are first processed individually. After that, the overall composition is produced in a video editing program by aligning the individual tracks with each other using a time axis. During the final step of video rendering, all of these individual files are merged into a single playable video file. This reduces the file size significantly, saving heaps of memory and allowing the file to be played on most playback devices.

The professional editing of digital photos is a similar process to that of videos. However, instead of individual tracks, various layers are used by the image editing program which each represent a certain layer of the image. In simple terms, the background, surroundings and focal object are typical layers of an image. Rendering is also the final production step for images. The individual image layers are merged to create an overall picture saved as a single image file.

Digital objects and models are primarily used in design, animation, architecture, and construction – wherever detailed and realistic representations are required to visualise an idea. In this case, the raw data concerns descriptions of objects and scenes composed in a markup language like HTML, XML or SVG. These descriptions specify both the purely geometric appearance of the object as well as parameters regarding surface structures, colours, perspectives, light sources, and more. Based on this information, the final object is created using a special rendering program. Here too, the raw data is processed in this way to reduce the requirements on computer memory and performance.