In environments such as those comprising in-vehicle routing or navigational systems, head-up displays (HUD) compared to head-down displays (HDD), have been found to result in decrease of the amount of time where driver's attention is diverted from the road. Indeed, HUD are usually placed at a location such that the driver does not need to tilt his or her head down in order to look at the display as it is the case with HDD. From a technical point of view, a HUD is a projector configured to project an input image onto a display surface such as a windshield of a car which then reflects the input image into the driver's line of sight. However, the input image projected to the surface is distorted because the display surface is not flat such that the driver sees a distorted version of the input image if specific precautions are not taken. In order to show an image with no distortion, it is needed to correct the curvature of the display surface using a so-called process of image warping. Indeed, image warping is commonly used to compensate for geometric and optical distortions thanks to the application of geometric transformations to an image that redefines the spatial relationship between points in the image. It is to be noted that such process of image warping can be done optically or electronically. A detailed description of the process of image warping can be found in the following document: George Wolberg, “Digital Image Warping”, IEEE Computer Society Press, 1988.
Common implementations of electronic image warping make use of memories external to the module performing the warping process. These external memories are used to temporarily store either or both the whole input image and the whole output image (i.e., the distorted version of the input image). Obviously, such implementations may have a huge impact on latency and cost of such warping modules since large memories are needed to store the full input image and/or the full output image. Thus as a solution, some documents suggest to implement the complete warping module on-chip without the use of off-chip memories by solely using the input line-buffer of the warping module which is configured to receive lines of pixels coming from the input image. Namely, instead of using a single line-buffer with a fixed length, it is proposed in such document to use one out of several line-buffer-based data structures within which each line-buffer is adapted in length to specific homogeneous section of the input image. The details of the foregoing implementation can be found in the following document: Andy Motten, Luc Claesen, Yun Pan, “Adaptive memory architecture for real-time image warping”, ICCD 2012, pages 466-471.
Notably, this document considers solely implementing the warping process into hardware in order to achieve low latency and reduce cost. However, this document is silent about how to dynamically determine the requirements for buffer management for each line-buffer so as to deliver the resulting output pixels on time to the display surface.