Iterative image compression for limited file sizes

摘要

An image data file (10) undergoes compression, such as JPEG compression (12). The size of the resulting compressed file (14) is compared (16) with a file size limit. If the limit is exceeded, the compression factor (Q) is increased. The invention provides a scaler (20) which is operated to reduce the image pixel resolution if the required compression factor (Q) would otherwise exceed a predetermined limit. This prevents a high degree of compression giving rise to an image of poor visual quality.