Image synthesis method and device for monitoring wide dynamic camera
A technology of image synthesis and camera, which is applied in the field of video processing, can solve the problems of poor adaptability of multi-frame synthesis processing control of wide dynamic cameras, etc., and achieve the effect of reducing false grayscale phenomenon, avoiding false grayscale phenomenon, and optimizing video picture
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Embodiment 1
[0093] In the above, in the step S3, the value of the lower limit factor of the synthetic weight is set to 0; in the step S4, the value of the upper limit factor is determined according to the judgment and calculation listed in the following table:
[0094]
[0095]
[0096] In this embodiment, setting the value of the lower limit factor to 0 can greatly simplify the calculation amount of the synthesis process. In terms of the design mechanism of the upper limit factor value, when the part of the long-exposure frame image exceeds 20% is highlighted, the overall possibility of overexposure is high, so the upper limit factor of the maximum value is selected to reduce the two frame images before and after. and load-bearing weights to reduce the false grayscale effect of this area due to overexposure on the final composition.
Embodiment 2
[0098] In the above, in the step S5, the pixel brightness range is 0-255; step S5 further obtains the upper limit threshold and the lower limit threshold in the following way,
[0099] S51) setting the lower limit threshold to be 50-76;
[0100] S52) Upper limit threshold=240+2*(exposure ratio of long-exposure frame to short-exposure frame-8).
[0101] In this embodiment, the processing and calculation process is more efficient by fixing the lower threshold and then calculating the upper threshold. The lower limit threshold setting is selected after a lot of experiments by the inventors. When the pixel brightness range is 0-255, the lower limit threshold value is set at 20%-30% of the overall brightness range for the best effect.
Embodiment 3
[0103] In the above, in the step S2, the ratio of pixels exceeding the brightness threshold in the long-exposure frame image is calculated according to the set brightness threshold, and the ratio is multiplied by at least 1000 to obtain the proportion of the highlighted part; the maximum of the upper limit factor The value is 1000.
[0104] In this embodiment, the calculated proportion (decimal point or percentage) is first converted into an integer, which can improve subsequent calculation efficiency. In addition, by multiplying by a value greater than 1000, the proportion of the highlighted part can be further subdivided so as to increase the precision of the subsequent weight calculation.
[0105] Concrete example:
[0106] for frame i , frame i+1 Composite two frames. Typically, in a single composition frame i is the long exposure frame, frame i+1 is the short exposure frame. The synthesis process is as follows, a method for image synthesis of a monitoring wide dyna...
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