The invention is related to a renderer for presenting, an image frame by help of a set of displaying commands. The invention is also related to a corresponding method.
A renderer receives displaying commands at its input and in turn executes displaying commands on an underlying platform's graphics system. By help of the renderer image frame sequences of a movie or of a computer animation as well as mixtures of still or moving images and animations can be presented on a display. For instance, an interactive menu related to a movie can be presented together with the movie.
To avoid artefacts or flickering the renderer executes the displaying commands on a back buffer while the screen is refreshed according to a screen refresh rate from a front buffer. After all executing all displaying commands related to a next image frame in the back buffer, all pixel values of the back buffer are blitted to the front buffer. That is, the pixel values in the back buffer are copied, preferably in a burst, to the front buffer. Then, the back buffer is cleared and displaying commands related to a image frame following the next image frame are executed by the renderer.
Executing of displaying commands, blitting and clearing are compute-intensive tasks. Therefore, presenting image frame sequences with a high image frame rate and/or high resolution still challenges the computational power and the graphics system of devices with embedded processors, like BD-players or mobile phones. To exclude unchanged pixels from displaying/blitting/clearing, a pixel-by-pixel comparison between the currently presented image frame in the front buffer and the next image frame in the back buffer appears as a straight forward solution. But, this comparison is as costly in terms of computational power, itself, that it almost provides no benefit.
Thus, there is a need for a renderer which allow rendering and presenting of image frame sequences with a high image frame rate and/or high resolution in face of limited computational power and for a respective method for presenting of image frame sequences.