Imaging apparatus using MJPEG compression method
An imaging apparatus includes at least one processor to implement: a re-sizer configured to re-size an image to a predetermined size, an encoder configured to encode the re-sized image, and a frame rate controller configured to calculate an actual bit rate of the encoded image for a preset period of time, compare a user-set target bit rate with the calculated actual bit rate, adjust a frame rate of the encoded image according to a result of the comparison, and output an encoded image signal at a user-set target bit rate irrespective of a complexity of the encoded image.
1. A method performed by an imaging apparatus to improve motion JPEG (MJPEG) quality, the method comprising:
calculating, by a frame rate controller, an actual bit rate of an encoded image for a preset period of time;
comparing, by the frame rate controller, a user-set target bit rate with the calculated actual bit rate;
adjusting, by the frame rate controller, a frame rate of the encoded image according to a result of the comparison, wherein the adjusting includes increasing the frame rate when the actual bit rate is less than a predetermined margin range of the user-set bit rate and decreasing the frame rate when the calculated actual bit rate is greater than the predetermined margin range of the user-set bit rate in order to improve image quality;
outputting, by the frame rate controller, the adjusted encoded image signal; and
wherein adjusting the frame rate of the encoded image according to a result of the comparison comprises:
increasing the frame rate when the actual bit rate is less than the user-set bit rate by a predetermined margin range until the actual bit rate is either within the predetermined margin range of the user-set bit rate or the frame rate reaches a user-set target frame rate, and
decreasing the frame rate when the calculated actual bit rate is greater than the predetermined margin range until the actual bit rate is either within the predetermined margin range of the user-set bit rate or the frame rate reaches the user-set target frame rate, wherein,
when increasing the frame rate, the frame rate is sequentially increased by X frames, where X is a natural number greater than 0, until the actual bit rate is either within the predetermined margin range of the user-set bit rate or the frame rate reaches a user-set target frame rate, and
when decreasing the frame rate, the frame rate is sequentially decreased by X frames, where X is a natural number greater than 0, until the actual bit rate is either within the predetermined margin range of the user-set bit rate or the frame rate reaches the user-set target frame rate.
2. A method performed by an imaging apparatus to improve motion JPEG (MJPEG) quality, the method comprising:
calculating, by a frame rate controller, an actual bit rate of an encoded image for a preset period of time;
comparing, by the frame rate controller, a user-set target bit rate with the calculated actual bit rate;
adjusting, by the frame rate controller, a frame rate of the encoded image according to a result of the comparison, wherein the adjusting includes increasing the frame rate when the actual bit rate is less than a predetermined margin range of the user-set bit rate and decreasing the frame rate when the calculated actual bit rate is greater than the predetermined margin range of the user-set bit rate in order to improve image quality;
outputting, by the frame rate controller, the adjusted encoded image signal; and
wherein adjusting the frame rate of the encoded image according to a result of the comparison comprises:
increasing the frame rate when the actual bit rate is less than the user-set bit rate by a predetermined margin range until the actual bit rate is either within the predetermined margin range of the user-set bit rate or the frame rate reaches a user-set target frame rate, and
decreasing the frame rate when the calculated actual bit rate is greater than the predetermined margin range until the actual bit rate is either within the predetermined margin range of the user-set bit rate or the frame rate reaches the user-set target frame rate,
further comprising adjusting a motion JPEG (MJPEG) quality factor until the actual bit rate is within the predetermined margin range of the user-set bit rate when the actual frame rate reaches the user-set target frame rate and the actual bit rate is not within the predetermined margin range of the user-set bit rate.
3. An imaging apparatus comprising:
a re-sizer configured to re-size an image to a predetermined size;
an encoder configured to encode the re-sized image;
a frame rate controller configured to calculate an actual bit rate of the encoded image for a preset period of time, compare a user-set target bit rate with the calculated actual bit rate, adiust a frame rate of the encoded image according to a result of the comparison, and output an encoded image signal at a user-set target bit rate irrespective of a complexity of the encoded image; and
wherein the re-sizer, encoder, and frame rate controller are located separately from each other, wherein the frame rate controller is further configured to, in response to the actual bit rate being less than the user-set target bit rate by X %, increase the frame rate of the encoded image, X being a natural number.
4. An imaging apparatus comprising:
a re-sizer configured to re-size an image to a predetermined size;
an encoder configured to encode the re-sized image;
a frame rate controller configured to calculate an actual bit rate of the encoded image for a preset period of time, compare a user-set target bit rate with the calculated actual bit rate, adiust a frame rate of the encoded image according to a result of the comparison, and output an encoded image signal at a user-set target bit rate irrespective of a complexity of the encoded image; and
wherein the re-sizer, encoder, and frame rate controller are located separately from each other, wherein the frame rate controller is further configured to generate a temporary pattern in response to a result of the comparison satisfying a preset condition whenever the user-set target bit rate is compared with the actual bit rate,
wherein the frame rate controller is further configured to generate a dynamic frame rate by adjusting the frame rate of the encoded image according to the result of the comparison, and
wherein the frame rate controller is further configured to perform pre-processing on the encoded image at the actual bit rate and the dynamic frame rate in response to the temporary pattern being equal to a preset pattern.
5. The imaging apparatus of claim 4 , wherein the preset condition is satisfied when the actual bit rate is greater than the user-set target bit rate by X % or the actual bit rate is less than the user-set target bit rate by Y %, each of X and Y being a natural number.