A method of determining a suitable configuration for a filter for pre-processing captured video images before performing OCR, the method comprising the step of: a) providing a captured sequence of images containing the same text content, the sequence of images comprising a first image in the sequence and a plurality of subsequent images in the sequence; b) selecting a configuration for a filter for pre-processing the images, from a plurality of available configurations; c) pre-processing the first image in the sequence using the selected filter configuration and submitting the pre-processed first image through an OCR process to extract text from the pre-processed first image; d) pre-processing an image of the plurality of subsequent images in the sequence using the selected filter configuration and submitting the pre-processed image of the plurality of subsequent images through an OCR process to extract text from the pre-processed image of the plurality of subsequent images; e) analysing the extracted text from the pre-processed first image and pre-processed image of the plurality of subsequent images to determine the performance of the filter, wherein the performance is determined to be positive if the extracted text is determined to be correct and wherein the determination of whether the extracted text is correct is made by comparison between the text extracted from the first image in the sequence and the text extracted from the image of the plurality of subsequent images in the sequence; and f) deciding the configuration is suitable and storing the suitable configuration, wherein steps d) through e) are performed on each image of the plurality of subsequent images in the sequence and the determination of whether the configuration is suitable is made when the performance of the selected filter configuration is determined to be positive for each of the plurality of subsequent images; wherein steps d) through e) are repeated for each successive image in the sequence as long as the extracted text is determined to be correct from the preceding image and wherein if the text extracted from an image of the plurality of subsequent images is determined to not be correct, selecting a different configuration for pre-processing the images, and repeating steps c) through f). a) providing a captured sequence of images containing the same text content, the sequence of images comprising a first image in the sequence and a plurality of subsequent images in the sequence; b) selecting a configuration for a filter for pre-processing the images, from a plurality of available configurations; c) pre-processing the first image in the sequence using the selected filter configuration and submitting the pre-processed first image through an OCR process to extract text from the pre-processed first image; d) pre-processing an image of the plurality of subsequent images in the sequence using the selected filter configuration and submitting the pre-processed image of the plurality of subsequent images through an OCR process to extract text from the pre-processed image of the plurality of subsequent images; e) analysing the extracted text from the pre-processed first image and pre-processed image of the plurality of subsequent images to determine the performance of the filter, wherein the performance is determined to be positive if the extracted text is determined to be correct and wherein the determination of whether the extracted text is correct is made by comparison between the text extracted from the first image in the sequence and the text extracted from the image of the plurality of subsequent images in the sequence; and f) deciding the configuration is suitable and storing the suitable configuration, wherein steps d) through e) are performed on each image of the plurality of subsequent images in the sequence and the determination of whether the configuration is suitable is made when the performance of the selected filter configuration is determined to be positive for each of the plurality of subsequent images;