ANIMATED BMP/WBMP FORMAT
Original Publication Date: 2001-Dec-03
Included in the Prior Art Database: 2001-Dec-03
Mobile messaging is evolving beyond text by taking a development path from Short Messaging Service (SMS) to Enhanced Messaging Service (EMS). The introduction of Enhanced Messaging Service and a Download Fun feature has brought the evolution of current GSM phones architecture. Additionally, the new animated BMP/WBMP format provides an extension to the current feature of EMS and the Download Fun feature.
In displaying multi-frames BMP image, for example a 4-frame image, it requires 4 frames of BMP image. With the same dimension of the images, all the header files will be the same. Instead of displaying the images frame by frame, this new animated BMP format plays the role in saving file size and the image data are stored in a single file as shown in Figure 1.
With a biOffBits field in BMP header file which specifies the byte offset from the BITMAPFILEHEADER structure to the actual bitmap data in the file, the decoder engine can determine the location of the first frame of the animated image. Then, with the widh and height information, the decoder engine can subsequently locate the next frame of image.
Aside to this, the width and height information of the animated BMP image is stored in the header file. Only one record of the dimension is stored since all frames have the same dimension. In this case, all other information is remained unchanged, the decoding algorithm only use the byte offset and the dimension information to process.
In order to distinguish between a static BMP and an animated BMP, the only different is its file size. Based on its width and height, its bitmap data size can be computed. The number of frames of an animated BMP/WBMP can be deduc...