Glossar-English:Interactive Images

Sub-Item to: Image Usage Types

Original: Interaktives Bild

---

Image presentation in interactive systems Like moving images (⊳ Film), interactive images are a pretty specific type of image with characteristic use conditions. An interactive road map, for example, is the pictorial output of a computer system that can be used to present a road map; in addition, the expression ‘interactive’ also promises that the map shown and its presentation can be influenced by the user in a non-trivial way, for instance by zooming, moving the section shown, enlarging or reducing the size of the labeling, omitting or adding railroad lines, rivers or sights, searching for an address and highlighting the result on the map, calculating and displaying a route, among others. Similarly, we expect an interactive anatomy atlas, like a traditional paper anatomy atlas, to contain anatomical drawings that can be shown to another person – or oneself in the role of another person. In addition, however, the interactive version should also allow the user to manipulate the drawings in a manner that goes far beyond the capabilities of a book. Strictly speaking, interactive images are a complexly organized set of images from which selected image sequences are automatically presented to an image user by an interactive system – usually a computer system – in such a way that the system reacts to the user's activities in real-time – i.e., without any noticeable delay. Therefore, they are digital media. The images of the set do not have to be available in advance as an image carrier (or in a syntactic notation such as jpg) but can be generated as required by means of computational visualistics. For this reason, the set on which the interactive image is based can also (theoretically) be infinitely large. Formally, the interactive image is the set of possible image sequences the interactive system under consideration can generate with the permitted user input. The concept of interactive images is closely related to other interactive media, such as those exemplified by the so-called natural language systems of “artificial intelligence” (AI). Instead of sequences of images from a set, sequences of verbal utterances from a given set are presented depending on the current user input. Figure 1: Still image of the oscilloscope screen from «Tennis For Two» As the existence of interactive images depends on computer systems and corresponding input and output devices, they have only appeared historically since around the mid-1950s. Oscilloscope displays that depend on user activity can be regarded as early forms. The «Tennis For Two» system developed by William Higinbotham in 1959, which used two rotary and two switching knobs for input and a simple laboratory oscilloscope as an output device, was probably one of the very first interactive images: On the circular screen of the oscilloscope, a deep horizontal “baseline” could be seen glowing on a dark background, in the middle of which a small vertical line rose up as a “net”. Above this, a luminous dot moved as a “ball”, the movement of which caused a slight tail to appear on the monitor (Fig. 1). The direction of the movement was reflected on the lines and followed a virtual gravitational force. In particular, however, it could be influenced by utilizing the buttons so that a game reminiscent of table tennis could be played between two users. On the concept of interactive systems Interactivity is, thus, not simply attributed to specific images as such; rather, it is generated by the interactive technical system, with the help of which sequences are presented from a predetermined or on-demand generated set of (“normal”) images. The term ‘interactive’ is somewhat awkward, as it connotes both ‘interaction’ and ‘medial interactivity’, neither of which is indeed meant. In the current context, it is really only a matter of ‘technical interactivity’, which initially means that a technical device reacts to user activities at all or even in a particularly pronounced way. In the early days of computer science, the “interaction” between humans and computers was essentially limited to first connecting a previously thoroughly prepared program – computer use was expensive, and the calculations were usually lengthy – in the form of punched cards or magnetic tapes, pressing a start button and waiting for the end of the calculation and the output of the result. Intervention during the computer run was not intended (and initially, apart from hard abort, not even possible). That essentially only changed at the beginning of the 1960s, and the paradigm shifted away from such 'batch jobs', as they were called, to interactive computer systems that could respond directly to user input at any time ([Licklider 1960a]Licklider, Joseph C. R. (1960): Man-Computer Symbiosis. IRE Transactions on Human Factors in Electronics, 1, 1. ). In the case of the media-based computer systems considered here, we are dealing with a particularly pronounced form of reactivity, which is also associated with certain specific features of the communication acts carried out via it. When we talk about interactive computer systems, we are referring, in particular, to quaternary media. In that type of media, several very different communication actions are intertwined: While the user “interacts” with the device (metaphorically), they also communicate with themselves in primary media, as the output depends decisively on their input; in addition, they are in secondary media communication with the author of the system, who is of course also responsible for the content and formal aspects of the respective outputs and their dependence on user input. Interactive images as quaternary media Not every user dependency leads to interactivity in the sense meant here. After all, the oscilloscope of a lie detector also produces graphic results that depend on the test person's physiological reactions or the questions the experimenter asks in real-time. A characteristic of interactive images in the sense of a quaternary medium lies in the ‘direct manipulation’ as it is called ([Shneiderman 1983a]Shneiderman, B. (1983): Direct Manipulation - A Step Beyond Programming Languages. IEEE Computer, 16, 8. ). This term refers to the fact that all objects (in the broad sense) referred to in a computer program, including images, for example, are, after all, merely in the form of coded descriptions. Therefore, changes to those are not really manipulations of corresponding objects but rather manipulations of the coded descriptions of such objects, i.e., the approximate conversion of one text into another text of the same type according to a certain rule. Direct manipulation occurs when the user is largely enabled to perform such manipulations as if the corresponding objects were actually being changed instead of the descriptions. In the case of interactive images, that means, provided that the image is indeed shown to the user as an image and not as an image-coding data structure (i.e., a corresponding graphic output device must be available), the user must be able to handle these immaterial images at least approximately in the same way as they are used to with material images. Special input devices have been developed for this purpose – from mouse and light pen to virtual buttons, sliders, and data gloves. Consequently, the computer system must feed back the input to the output in pretty fast cycles, namely so fast that the actual processing time required to analyze the input, make corresponding changes to the coded image description, and output the resulting description as an image is no longer (or hardly) noticeable to the user. The manipulation is direct in two respects: (i) (apparently) not via the detour of informatic coding, and (ii) in its effect (almost) without delay. When presenting images using interactive systems, two levels of direct manipulation can be distinguished: (a) Influencing the presentation parameters: The image is thus manipulated as an image. That includes, in particular, changing the size and rotation, changing the contrast, or embedding in larger layouts through simple hand movements by the user. The fact that an image can be “dragged” to a certain position with the mouse, enlarged by “pulling the corners”, and rotated by moving the mouse after a specific mouse click, for example, are usually basic options for image editing software. Figure 2: Sketch of the difference between computer graphic image generation when the images are (b) generated in an interactive system or (a) not so (b) Influencing the displayed image content: Depending on the image type, this involves (i) a selection from a given set according to variable content criteria, (ii) the computer-graphic generation of corresponding images from a modifiable 3D model (Fig. 2) or (iii) computer visualization from influenceable data sets. Direct manipulations of 3D models, which in turn can be differentiated into three subtypes, are particularly revealing: (b1) Influencing the visualization type (changing the rendering algorithm): In addition to several so-called photorealistic rendering algorithms, the calculation of the two-dimensional projection from the 3D model can make use of a variety of non-photorealistic algorithms so that the resulting image can appear in a wide range of stylistic variations (cf. [Sachs-Hombach & Schirra 2002a]Sachs-Hombach, Klaus & Schirra, Jörg R.J. (2002): Selecting Styles for Tele-Rendering: Toward a Rhetoric in Computational Visualistics. In: Butz, A. & Krüger, A. & Olivier, P. & Schlechtweg, S. & Zhou, M. (Hg.), Proc. 2nd International Symposium on Smart Graphics. ACM Press, Hawthorne, NY. ). In this way, the viewer's attention can be drawn to specific parts of the image content (or to the image character as such, ⊳ Image in reflexive use). (b2) Influencing the model (transformations of depicted objects, lighting): This type of modification forms a basis for the immersion effects of cyberspace. By allowing a user to influence the objects presented in the image (almost) as if they were real objects, for instance, by using a mouse or data glove to push, pull, or turn them with a hand movement, the difference between the image of the object and its unmediated perception is at least partially eliminated (⊳ Deceptive and immersive mode). Influencing the “ball” in «Tennis for Two», “opening” a “door” in a modern computer game, or “moving” a file on a “desktop” are typical examples of this type of manipulation. (b3) Influencing the perspective (movements and parameters of the virtual “camera”); although these manipulations are at least partially equivalent in effect to the changes mentioned under (a), they do not affect the reception situation of the image, but rather its production situation. In combination with (b2), however, the decisive prerequisite for immersion in cyberspace arises: the virtual camera becomes the user's “eye”, so to speak, which the user can move “directly” through the virtual world determined by the 3D model (⊳ Virtuality), if not in the same way as their own, then at least in close analogy to their body orientation and movement. As with all quaternary media, the question arises as to who is communicating with whom and on what level using interactive images. On the one hand, there is a similarity to secondary media in that the authors of the interactive system (usually unknown to the system users and referred to as ‘the computer visualists’ in Figure 2) can be regarded as the actual senders. However, since the system users each also appear at least partially as both the sender and receiver of those interactions, as they want to show themselves something with the generated image (e.g., a route in the interactive road map), there is also a relationship to primary media with the possibility of direct deixis. Since the selection of the updated sign act is made “autonomously” by the system in the current situation, corresponding pointing gestures and deictic utterances can occur in it, assuming that the system has access to the objects present there. These interpretations are inseparably intertwined. Interactional, expressive, and propositional angles vary accordingly. Consequently, one of the main tasks in designing such systems is to ensure the best possible fit with the user's actions and communication intentions through components such as user models. On the other hand, every user must be aware that this is communication mediated by a highly complex medium, with all the limitations and peculiarities that this entails, no matter how much it may resemble communication in a primary medium in individual cases. . . Dauert ein bißchen! Figure 3: Example of a simple interactive image (currently slightly faulty) A simple example A relatively simple example is given in this glossary on the main page and is taken up in a slightly varied form in Figure 3: The list of categories by which the glossary is organized, rendered with typographical variations as a word cloud, reacts to movements of the cursor across the image area that the viewer triggers with the mouse. The word cloud begins to appear to rotate in three-dimensional space, with the angle and speed of rotation being determined by the distance of the cursor position currently selected by the user from the center of the image. The movement would stop if the cursor were positioned precisely on the center point. Incidentally, it does this automatically after an extended deceleration phase when the cursor leaves the screen. (Note: The current version reacts somewhat differently.) See also: Image Content Image in reflective use Image Syntax Computational Visualistics Computer Graphics Cyberspace Dezeptive and immersive Modes Digital media Film Iconic difference Interaction and Communication Interactional, Expressive, and Propositional Angles Notation Typologies of Media Virtuality

Notes Literature [Licklider 1960a]Licklider, Joseph C. R. (1960): Man-Computer Symbiosis. IRE Transactions on Human Factors in Electronics, 1, 1.[Sachs-Hombach & Schirra 2002a]Sachs-Hombach, Klaus & Schirra, Jörg R.J. (2002): Selecting Styles for Tele-Rendering: Toward a Rhetoric in Computational Visualistics. In: Butz, A. & Krüger, A. & Olivier, P. & Schlechtweg, S. & Zhou, M. (Hg.), Proc. 2nd International Symposium on Smart Graphics. ACM Press, Hawthorne, NY.[Shneiderman 1983a]Shneiderman, B. (1983): Direct Manipulation - A Step Beyond Programming Languages. IEEE Computer, 16, 8.[Van Deemter 1998a]Van Deemter, K (1998): Retrieving Pictures for Document Generation. In: Hiemstra, D. & de Jong, F.M.G. & Netter, K. (Hg.), Proc. of 14th Workshop on Language Technology. University of Twente, Twente. Version 1: 2013 Responsible: Schirra, Jörg R.J. Editing: Halawa, Mark Contributions by: Joerg R.J. Schirra und Marcel Lemmes — (Note) Quote as: Schirra, Jörg R.J. (2013). Interactive Images. (Ausg. 1). In: Schirra, J.R.J.; Halawa, M. & Liebsch, D. (Hg.), Glossar der Bildphilosophie. (2012-2026). [bildglossar.org/index.php?title=Glossar-English:Interactive_Images].