Determination method for white-point and correction method of the white balance

A determination method for white-point of the white balance, comprising:

• detecting a plurality of gray cards with different reflection coefficients in a range from a first color temperature to a second color temperature according to properties of an image sensing device such that at least a first group of color temperature data and a second group of color temperature data on a first color coordinates are obtained, wherein the second color temperature is larger than the first color temperature;
• performing a coordinate rotation operation for data detected in the range from the first color temperature to the second color temperature to obtain a white-point plane on a second color coordinates, and an error caused by projecting the color temperature data on the white-point plane is minimized;
• forming a white-point gray line of the first color temperature and a white-point gray line of the second color temperature on the white-point plane after the coordinate rotation operation is performed for the first group of color temperature data and the second group of color temperature data, wherein the white-point gray line of the first color temperature and the white-point gray line of the second color temperature are intersected to form a fan area, so as to set the white-point range of the low saturation of the image sensing device, wherein the white-point gray line of the first color temperature is a line connecting a dark point and the white-point of the first color temperature, and the white-point gray line of the second color temperature is a line connecting the dark point and the white-point of the second color temperature, and the dark point is a collection of white-points at all color temperature;
• obtaining an image datum on the first color coordinates;
• performing the coordinate rotation operation for the image datum to rotate the distortion of the image, and the color of the image of the object may be clear to the color of the object which people can see, or the color temperature may be corrected to be an appropriate value.
• It will be apparent to those skilled in the art that various modifications and variations can be made to the structure of the present invention without departing from the scope or spirit of the invention. In view of the foregoing, it is intended that the present invention cover modifications and variations of this invention provided they fall within the scope of the following claims and their equivalents. image datum to be on the second color coordinates to obtain a rotated image datum;
• calculating a vertical projection for the rotated image datum to obtain a placement datum on the white-point plane, and calculating a difference value between the rotated image datum and the placement datum;
• and
• determining whether the image datum is a white-point according to the difference value and relationship between the placement datum and the fan area.