Patent EA-001171-B1 (EA)
Title: Device and process for producing a composite picture
Inventor: RYBCZYNSKI ZBIGNIEW
IPC: H04N9/75
Filed: 1997-04-30
Abstract: 1. Apparatus for producing a composite image from a foreground image (FG), showing an object or a scene with a substantially monochrome background, and a background image (BG) comprising a first processing unit (R4) for producing a control signal (SEP) for each pixel of the foreground image (FG), reflecting whether an individual pixel of the foreground image is part of the object or part of the monochrome background, based both on the chromatic values of the pixel and on predetermined chromatic values, describing the color composition of the monochrome background, and a selection unit (R5) suffixed to the first processing unit (R4), for calculating the chromatic values of an individual pixel of the composite image from, depending on the control signal (SEP), either the chromatic values of the corresponding pixel of the foreground image (FG) or the chromatic values of the corresponding pixel of the background image (BG), characterized by a second processing unit (R11, R12, R14, R17) for calculating correction values for the chromatic values of an individual pixel of the composite image, based on the chromatic values of the corresponding pixel of the foreground image (FG) and/or of the background image (BG), in order to achieve a natural pictorial appearance, an image processing unit (19) suffixed to the second processing unit (R11, R12, R14, R17), for changing the chromatic values of an individual pixel of the composite image corresponding to the correction values, previously calculated by the second processing unit (R11, R12, R14, R17) for this pixel. 2. Apparatus according to claim 1, characterized in that the first processing unit (R4) is linked to a first input unit (6) to set the predetermined chromatic values reflecting the color composition of the monochrome background of the foreground image (FG). 3. Apparatus according to claim 1 or 2, characterized by an input device for loading the chromatic values of an individual pixel of the foreground image (FG) and of the background image (BG), and an output device for outputting the chromatic values of the corresponding pixel of the composite image (KB2). 4. Apparatus according to claim 1 or 2, characterized by an input device for loading a first data record representing the foreground image (FG), whose elements each contain the chromatic values of an individual pixel of the foreground image, and a second data record representing the background image (BG), whose elements each contain the chromatic values of an individual pixel of the background image (BG), an output device for outputting a third data record representing the composite image (KB2), whose elements each contain the chromatic values of an individual pixel of the composite image (KB2). 5. Apparatus according to claim 4 characterized by a first storage matrix (1) for storing the first data record, and/or a second storage matrix (2) for storing the second data record, and/or a third storage matrix (21) for storing the third data record. 6. Apparatus according to claim 5 characterized by a third processing unit suffixed to the first storage matrix and prefixed to the first processing unit (R4), for calculating the predetermined chromatic values, which characterize the monochrome background of the foreground image (FG), as the average value of the chromatic values of the foreground image (FG). 7. Apparatus according to claim 5 or 6 characterized in that the second processing unit (R11, R12, R14, R17) is prefixed to a fourth storage matrix (18) for storing a fourth data record, wherein each element of the fourth data record contains the correction values for an individual pixel of the composite image, calculated by the second processing unit (R11, R12, R14, R17). 8. Apparatus according to one of the preceding claims characterized by a second input unit (20) prefixed to the image processing unit (R19) for the input of weighting factors for the correction values calculated by the second processing unit (R11, R12, R14, R17). 9. Apparatus according to one of the preceding claims, characterized in that the primary colors are red, green and blue. 10. Apparatus according to one of the preceding claims, characterized in that the chromatic values are in the range between 0 and 255. 11. Method for producing a composite image from a foreground image (FG) showing an object with a substantially monochrome background and a background image (BG), wherein for each pixel of the foreground image (FG) a control signal (SEP) is calculated based on both the chromatic values of a given pixel and on the predetermined chromatic values reflecting the color composition of the monochrome background, which indicates whether the pixel is part of the object or part of the monochrome background, and the chromatic values for each pixel of the composite image (KB1) are calculated based on the chromatic values of the corresponding pixel either of the foreground image (FG) or of the background image (BG), depending on the control signal (SEP), characterized in that for each pixel of the composite image (KB1) correction values are calculated, based on the chromatic values of the corresponding pixel of the foreground image (FG) and/or of the background image (BG), and the chromatic values of the composite image (KB1) are changed in each pixel according to the correction values in order to achieve a natural pictorial appearance. 12. Method according to claim 11 characterized in that for pixels depicting the object in the foreground image (FG) a transparency value is calculated, based on both the predetermined chromatic values characterizing the color composition of the monochrome background and on the chromatic values of the pixel, reflecting the transparency of the object in this pixel, the correction values for pixels depicting the object in the composite image (KB1) are calculated based on the chromatic values of the foreground image (FG) and of the background image (BG), depending on the transparency value. 13. Method according to claim 11 or 12 characterized in that for pixels depicting the monochrome background in the foreground image (FG) a first luminosity value, describing the intensity of the shadows cast by the object on the monochrome background, is calculated, based both on the chromatic values characterizing the color composition of the monochrome background and on the chromatic values of the pixel, the correction values for pixels of the composite image depicting the background image (BG) are calculated in order to reconstruct the shadows cast by the object on the background image (BG), based on the first luminosity value. 14. Method according to one of the claims 11 to 13 characterized in that for pixels depicting the monochrome background in the foreground image (FG) a second luminosity value, describing the intensity of the Illuminations on the monochrome background caused by reflections at the object, is calculated, based on both the chromatic values characterizing the color composition of the monochrome background and on the chromatic values of the pixel, the correction values to reproduce reflections in the composite image are calculated for pixels of the composite image depicting the background image (BG) based on the second luminosity value. 15. Method according to one of the preceding claims characterized in that the background image (BG) is subdivided in a plurality of sections and for each section the average values of the chromatic values of the individual pixels are calculated, the correction values for pixels depicting the object in the composite image are calculated based on the average values of all sections.