Device for Detecting Anomalies in a Digital Image

Device for detecting anomalies in a digital image, called obtained image, said image comprising geometrical or alphanumeric symbols, said device comprising means of storing said obtained image and a second image called anticipated image and a viewing device, the two images consisting of coloured pixels referenced in a plane φ(x, y), each pixel PO(x, y) of the obtained image having three red, green and blue components, respectively denoted PO(x, y, R), PO(x, y, G) and PO(x, y, B), and each pixel PA(x, y) of the anticipated image also having three red, green and blue components, respectively denoted PA(x, y, R), PA(x, y, G) and PA(x, y, B), for any pixel, the sum of its three components being called luminance, the luminances being denoted PO(x, y, L) and PA(x, y, L),

• the said device comprising means of comparing the two obtained and anticipated images, and means of generating a third image, called resultant image, each pixel PR(x, y) of the resultant image having three red, green and blue components, respectively denoted PR(x, y, R), PR(x, y, G) and PR(x, y, B) defined as follows:
• if the three components of a pixel PO(x, y) of the obtained image are all identical to the three components of the pixel PA(x, y) situated in the same place in the anticipated image, then the three components of the pixel PR(x, y) are all equal and proportional to the luminance PA(x, y, L) of the corresponding pixel of the anticipated image;
• if at least one of the three components of a pixel PO(x, y) of the obtained image is different from the corresponding component of a pixel PA(x, y) situated in the same place in the anticipated image, then the red component PR(x, y, R) of the pixel PR(x, y) depends on the luminance PO(x, y, L) of the corresponding pixel of the obtained image, the green component PR(x, y, G) of the pixel PR(x, y) depends on the luminance PA(x, y, L) of the corresponding pixel of the anticipated image, the blue component being zero.